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Reviewed on Jan 22, 2019 , Eric Bousquet, Yannick Khong

Samsung C34J791/CJ791
MONITOR REVIEW

Usage Ratings - Version 1.0

Test Benches:

  • 1.0: Fall 2017
7.2
Mixed Usage
Score components:
Size : 34 "
Resolution : 3440x1440
Refresh Rate : 100 Hz
LCD Type
What it is: Type of LCD technology used by the monitor.
When it matters: Different technologies have different viewing angle properties.
:
VA
Variable Refresh Rate
What it is: Feature that allows the monitor to synchronize its refresh rate with the input device's output and reduces stuttering and screen tearing.
When it matters: Almost every usage, but is most noticeable in gaming where constant fluctuation in framerate cause distracting artifacts.
:
FreeSync

The Samsung C34J791 is a 34'' ultrawide monitor with mediocre picture quality. It has a high contrast ratio due to its VA panel and displays deep but not too uniform blacks. It is more suitable for an average lit room as it cannot get very bright to fight bright room glare. It has great gray uniformity, which is great for browsing the web, but the bad viewing angles make it unsuitable for working side by side with a colleague. It has great motion handling with a fast 100Hz refresh rate, supports FreeSync and has a low input lag to please gamers.

This is a newer version of the Samsung CF791.

Test Results
Design 8.0
Picture Quality 6.3
Motion 8.6
Inputs 9.2
Pros
  • Excellent low input lag
  • Excellent resolution and size
Cons
  • Image degrades when viewed at an angle
  • Lack of HDR support

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8.0

Design

Score components: Subjectively assigned
Samsung C34J791/CJ791 Design Picture
Curved : Yes
Curve radius : 1500R
Weight (without stand)
What it is: The weight of the monitor when mounted. This is with the stand removed, and if necessary any VESA mounting bracket attached.
When it matters: When choosing a mount for a monitor/
:
15.0 lbs (6.8 kg)
Weight (with stand)
What it is: The weight of the monitor including the stand any any input covers.
:
16.5 lbs (7.5 kg)

The design of the Samsung CJ791 is very good. It is identical to the design of the Samsung CF791. It has the same flat round stand that supports the monitor well and prevents serious wobbling. You can adjust the height and tilt, but you cannot swivel or rotate the screen and this will disappoint those who regularly share their work with a colleague. Due to the curve profile, it looks slightly thick, and finally, the overall build quality is very good and you should have no issues with it.

Stand
Samsung C34J791/CJ791 Stand picture
Width
What it is: The width of the stand.
When it matters: When using a small desk, for those who require a monitor with a small footprint.
:
9.6" (24.4 cm)
Depth
What it is: The depth of the stand.
When it matters: When using a small desk, for those who require a monitor with a small footprint.
:
12.2" (31.0 cm)

The stand of the Samsung C34J791 is round and flat. It supports the monitor well and only allows minimal wobbling.

4.7 Ergonomics
What it is: How much the position of the screen can be adjusted to match the viewing preference of the user.
When it matters: All usages, but especially office and gaming use.
Score components:
  • 46% Height Adjustment
  • 18% Switch portrait/landscape
  • 18% Swivel Range
  • 18% Tilt Range
Samsung C34J791/CJ791 Ergonomics picture
Height Adjustment
What it is: The amount of vertical travel or adjustment of the display.
:
3.9" (9.9 cm)
Switch portrait/landscape : No
Swivel Range : N/A
Tilt Range : -20° to 15°

The tilt range varies along the height adjustment positions:
@ top: 15° to -20°
@ bottom: 2.5° to -17.5°

The ergonomics of the monitor are poor. You will not have an easy task adjusting it to a comfortable position. You can adjust the height and tilt the screen, but you cannot swivel or rotate it to portrait.

Back
Samsung C34J791/CJ791 Back picture
Wall Mount : VESA 100x100, VESA 200x200

The back of the monitor is plain and it looks identical to the back of CF791. It has a compartment (that comes with a cover) that houses most of the inputs. Outside this compartment, there are two USB ports and a headphones jack that are pointing outward.

Just like the CF791, the CJ791can be VESA mounted in either 100x100 or 200x200 VESA wall mounts using the included adapter.

The monitor offers cable management through the stand.

Borders
Samsung C34J791/CJ791 Borders picture
Borders
What it is: The distance from the left edge of the display to the start of the image.
When it matters: When using multiple monitors side-by-side.
:
0.4" (1.0 cm)

The borders are thin and look elegant. They are metal and have a chrome finish just like the CF791. In the image, they look more white due to the camera flash.

Thickness
Samsung C34J791/CJ791 Thickness picture
Thickness (with stand)
What it is: How far the front of the screen protrudes when placed as far back as possible against a wall.
When it matters: When the monitor is placed back against a wall.
:
8.3" (21.1 cm)
Thickness (without stand)
What it is: How far the front of the screen protrudes when the stand has been removed. For monitors which require a bracket to VESA mount this measurement includes the thickness of the bracket.
When it matters: When mounting a monitor with the stand removed.
:
6.5" (16.5 cm)

The monitor is thick, especially when placed on its stand. If you VESA mount it, it will not protrude much but it will not look very thin either due to the curve.

8.0 Build Quality
What it is: How well built and sturdy the monitor is, and how good the materials used to build it are.
When it matters: All usages.
Score components: Subjectively assigned
Samsung C34J791/CJ791 Build Quality picture

The Samsung C34J791 has a very good built quality. You will not find any gaps or loose ends and you should not have any issues with it.

The Samsung C34J791 has a mediocre picture quality. Although it has a high native contrast ratio, its performance in a dark room is hurt by the poor black uniformity and the lack of local dimming. It cannot get very bright to fight the glare of a bright room and its viewing angles are bad. On the positive side, the monitor has great gray uniformity and can display a rich palette of colors in SDR and in various luminance levels. It does not support HDR.

7.8 Contrast
What it is: Brightness difference between white and black. This is the main component of picture quality.
When it matters: Always, but especially when watching dark scenes.
Score components:
Samsung C34J791/CJ791 Checkerboard Picture
Native Contrast
What it is: Ratio of the white brightness divided by the blacks measured on our checkerboard test pattern with a white target of 100 cd/m².
When it matters: Dark scenes in a dark room.
Good value: > 3,000
Noticeable difference: 500
:
2904 : 1
Contrast with local dimming
What it is: Ratio of the white brightness divided by the blacks measured on our checkerboard test pattern with local dimming turned on (maximum) with a white target of 100 cd/m².
When it matters: Dark scenes in a dark room.
Good value: > 3,000
Noticeable difference: 500
:
N/A

Just like the CF791 the Samsung C34J791 has a very good native contrast ratio due to its VA panel. Blacks look deep in a dark room and this improves picture quality.

0 Local Dimming
What it is: The lights behind the LCD layer adapt to the picture displayed, improving the contrast ratio.
When it matters: Dark scenes viewed in a dark room.
Score components: Subjectively assigned
Local Dimming
What it is: Whether it has a feature that controls the LEDs behind the LCD layer, to match the picture and darkens the dark portion of it.
When it matters: On LED TVs only. Dark scenes viewed in a dark room.
:
No
Backlight
What it is: Configuration of the lights of the backlight.
When it matters: Effectiveness of the local dimming.
Good value: Full-array/direct lighting is better for local dimming. As for the uniformity of the screen, it depends on the implementation. Some edge-lit monitors have more uniform blacks than some full-array monitors.
:
Edge

The Samsung CJ791 does not have a local dimming feature. The video is for reference only.

6.9 SDR Peak Brightness
What it is: How bright the screen can get. Measured with local dimming and with SDR content.
When it matters: Bright living rooms; bright objects; SDR content.
SDR Real Scene
What it is: The maximum luminosity the monitor can obtain while playing a movie or while watching a TV show. Our Real Scene was selected to represent a more regular movie condition. All measurements are made with the TV set to be as bright as possible, but with a 6500k white. Measured with local dimming on, max backlight and with an SDR signal. Scene: here.
When it matters: When watching movies and TV shows in SDR.
Good value: > 300 cd/m²
Noticeable difference: 30 cd/m²
:
251 cd/m²
SDR Peak 2% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 2% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: Bright highlights, present on screen for a short time
:
248 cd/m²
SDR Peak 10% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 10% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: Bright objects, present on screen for a short time
:
249 cd/m²
SDR Peak 25% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 25% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: When watching in a bright room.
:
249 cd/m²
SDR Peak 50% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 50% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: When watching in a bright room.
:
248 cd/m²
SDR Peak 100% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 100% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: When watching in a bright room.
:
248 cd/m²
SDR Sustained 2% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 2% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: Bright highlights, persistent during a scene.
:
248 cd/m²
SDR Sustained 10% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 10% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: Bright objects, persistent during a scene.
:
249 cd/m²
SDR Sustained 25% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 25% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: When watching in a bright room.
:
249 cd/m²
SDR Sustained 50% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 50% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: When watching in a bright room.
:
248 cd/m²
SDR Sustained 100% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 100% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over SDR signal.
When it matters: When watching in a bright room.
:
248 cd/m²
SDR ABL
What it is: The standard deviation of the SDR sustained brightness, after linearizing for noticeable differences in luminosity
When it matters: Content with large bright areas, such as for PC or video game use, and sports such as hockey
:
0.000

The CJ791 has decent SDR peak brightness. It is ok for an average lit room but it cannot overcome the glare of a bright room. The level of brightness remains constant across the various bright window sizes and this is great. The SDR Real Scene measurement appears a little higher due to uniformity issues at the position of the screen where the measurement is made.

The tests were done using the 'Custom' (calibrated) Picture Mode.

0 HDR Peak Brightness
What it is: How bright the screen can get. Measured with local dimming and with HDR content.
When it matters: HDR content
HDR Real Scene
What it is: The maximum luminosity the monitor can obtain while playing a movie or while watching a TV show. This scene was selected to represent a more realistic movie condition. All measurements are made with the monitor set to be as bright as possible, but with a 6500k white. Measured with local dimming, max backlight and over HDR signal. Scene: here.
When it matters: When watching movies or watching TV show in HDR.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Peak 2% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 2% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright highlights, present on screen for a short time; especially for HDR content.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Peak 10% Window
What it is: TThe maximum luminosity, even if only maintained for a short time, of a white square covering 10% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright objects, present on screen for a short time; especially for HDR content.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Peak 25% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 25% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright rooms; bright objects in HDR video.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Peak 50% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 50% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright rooms.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Peak 100% Window
What it is: The maximum luminosity, even if only maintained for a short time, of a white square covering 100% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright rooms.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Sustained 2% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 2% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright highlights, persistent throughout a scene; especially for HDR content.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Sustained 10% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 10% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright highlights, persistent throughout a scene; especially for HDR content.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Sustained 25% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 25% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright highlights, persistent throughout a scene; especially for HDR content.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Sustained 50% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 50% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright rooms.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR Sustained 100% Window
What it is: The lowest maximum luminosity (usually after it has stabilized) of a white square covering 100% of the screen, with the monitor set to be as bright as possible. Measured with local dimming and over HDR signal (if supported).
When it matters: Bright rooms.
Good value: > 550 cd/m²
Noticeable difference: 80 cd/m²
:
N/A
HDR ABL
What it is: The coefficient of variation of the HDR sustained brightness, after linearizing for noticeable differences in luminosity
When it matters: HDR content with large bright areas, such as HDR gaming
Good value: <0.07
Noticeable difference: 0.01
:
N/A

HDR is not supported.

4.8 Horizontal Viewing Angle
What it is: Color accuracy when viewed from the side.
Samsung C34J791/CJ791 Horizontal Color Shift Picture
Color Shift from Left
What it is: Angle where the colors noticeable shift compared to when viewed from directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When sharing your monitor with people on your left
Good value: > 50°
Noticeable difference: 10°
:
31 °
Color Shift from Right
What it is: Angle where the colors noticeable shift compared to when viewed from directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When sharing your monitor with people on your right
Good value: > 50°
Noticeable difference: 10°
:
30 °
Samsung C34J791/CJ791 Horizontal Brightness Picture
Brightness from Left
What it is: Angle where the brightness drops to 50% of the brightness directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When sharing your monitor with people on your left.
Good value: > 50°
Noticeable difference: 10°
:
44 °
Brightness from Right
What it is: Angle where the brightness drops to 50% of the brightness directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When sharing your monitor with people on your right.
Good value: > 50°
Noticeable difference: 10°
:
40 °
Samsung C34J791/CJ791 Horizontal Black Level Picture
Black Level from Left
What it is: Angle where the black level drops to 50% of the black level directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When sharing your monitor with people on your right.
Good value: > 50°
Noticeable difference: 10°
:
13 °
Black Level from Right
What it is: Angle where the black level drops to 50% of the black level directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When sharing your monitor with people on your right.
Good value: > 50°
Noticeable difference: 10°
:
13 °
Curve Radius : 1500 R

Poor horizontal viewing angles as expected for a VA panel monitor. As soon as you deviate from the center axis, the image darkens and is no longer accurate. This is not good if you need to share your screen with a colleague.

4.6 Vertical Viewing Angle
What it is: Color accuracy when viewed from the top or bottom.
Samsung C34J791/CJ791 Vertical Color Shift Picture
Color Shift from Below
What it is: Angle where the colors noticeable shift compared to when viewed from directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When looking at a monitor from below.
Good value: > 50°
Noticeable difference: 10°
:
26 °
Color Shift from Above
What it is: Angle where the colors noticeable shift compared to when viewed from directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When looking at a monitor when standing up.
Good value: > 50°
Noticeable difference: 10°
:
23 °
Samsung C34J791/CJ791 Vertical Brightness Picture
Brightness from Below
What it is: Angle where the brightness drops to 50% of the brightness directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When looking at a monitor from below.
Good value: > 50°
Noticeable difference: 10°
:
37 °
Brightness from Above
What it is: Angle where the brightness drops to 50% of the brightness directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When looking at a monitor while standing up.
Good value: > 50°
Noticeable difference: 10°
:
35 °
Samsung C34J791/CJ791 Vertical Black Level Picture
Black Level from Below
What it is: Angle where the black level drops to 50% of the black level directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When looking at a monitor from below.
Good value: > 50°
Noticeable difference: 10°
:
6 °
Black Level from Above
What it is: Angle where the black level drops to 50% of the black level directly in front of the monitor. 0 ° means directly facing the monitor. Measurements are up to a maximum of 75 °.
When it matters: When looking at a monitor while standing up.
Good value: > 50°
Noticeable difference: 10°
:
5 °

The vertical viewing angles are poor. Anyone standing next to you will see a much darker image than what you are seeing. In order for them to see the same image quality, they have to bring their head to where yours is.

8.2 Gray Uniformity
What it is: Evenness of colors onscreen (not just gray).
When it matters: Solid colors. Sports, panning shots.
Score components:
Samsung C34J791/CJ791 50% Uniformity Picture
50% Std. Dev.
What it is: Average squared difference of pixels when displaying a mid 50% gray.
When it matters: Solid colors. Sports, panning shots.
Good value: < 2.5%
Noticeable difference: 1%
:
4.951 %
50% DSE
What it is: Dirty Screen Effect. High-frequency variance of uniformity. Dark spots on the screen.
When it matters: Solid colors. Sports, panning shots.
Good value: < 0.165%
Noticeable difference: 0.025%
:
0.112 %
Samsung C34J791/CJ791 5% Uniformity Picture
5% Std. Dev.
What it is: Average squared difference of pixels when displaying a mid 5% gray.
When it matters: Dark scenes.
Good value: < 1.15%
Noticeable difference: 1%
:
0.915 %
5% DSE
What it is: Dirty Screen Effect. High-frequency variance of uniformity. Dark spots on the screen.
When it matters: Dark scenes.
Good value: < 0.116%
:
0.059 %

The gray uniformity of the CJ791 is great. In the 50% gray image, you can spot some clouding and the sides look darker. However, there is almost no dirty screen effect (DSE) and this great news if you spend a lot of time surfing the web.

In the 5% gray image the uniformity is better and no DSE is noticeable.

4.9 Black Uniformity
What it is: Evenness of blacks.
When it matters: Dark scenes viewed in a dark room.
Score components:
Samsung C34J791/CJ791 Native Black Uniformity Picture
Native Std. Dev.
What it is: Average of the squared difference of the blacks.
When it matters: Dark scenes viewed in a dark room.
Good value: <2%
Noticeable difference: 1%, but keep in mind that it varies a lot by unit, even of the same model; yours likely will not end up exactly like ours.
:
2.766 %
Std. Dev. w/ L.D.
What it is: Average of the squared difference of the blacks with Local Dimming enabled
When it matters: Dark scenes viewed in a dark room.
Good value: <2%
Noticeable difference: 1%, but keep in mind that it varies a lot by unit, even of the same model; yours likely will not end up exactly like ours.
:
N/A

Poor black uniformity for the Samsung CJ791. Just like the Samsung CF791 there is scattered clouding in various areas of the screen that most people will notice when viewing dark scenes in a dark room.

7.3 Pre Calibration
What it is: Monitor's color accuracy before a full calibration. The measurements are taken with out of the box 'factory setting'.
When it matters: All video on an uncalibrated TV. This represents most people's use cases.
Score components:
Samsung C34J791/CJ791 Pre Calibration Picture Samsung C34J791/CJ791 Pre Gamma Curve Picture Samsung C34J791/CJ791 Pre Color Picture
Picture Mode
What it is: The picture mode that was used to do the pre-calibration reading. We usually go for the picture mode that gives us the more control over all the picture quality setting.
:
Custom
Luminance
What it is: The luminance at which the pre-calibration reading was done. This represents the luminance of the monitor when it is at the factory default settings.
:
117 cd/m²
Luminance Settings
What it is: The luminance settings, often named 'Brightness' on monitors, usually range from 0 to 100.
:
53
Contrast Setting
What it is: The monitor contrast setting, usually ranging from 0 to 100.
:
75
RGB controls
What it is: This is the value for each color (red, green, and blue) used in the monitor internal RGB cuts/gains controls. If the monitor does not have an internal RGB cuts/gains controls, then the color temperature setting will be used instead, and the color temperature that gives us the best result will be used.
:
Cool 1
Color Temperature
What it is: The color temperature is a measure of the color of light. A colder color temperature (7000K) will look bluer and a warmer color temperature (4000K) will look yellower/redder. 6500K is the standard color for PC monitors and also for the sRGB color standard.
When it matters: When you care about color reproduction and accuracy.
Good value: 6500K
Noticeable difference: 400K
:
6879 K
White Balance dE
What it is: Average inaccuracy of shades of gray.
When it matters: Overall color temperature of all video.
Good value: < 3
Noticeable difference: 1
:
3.52
Color dE
What it is: Average inaccuracy of colors.
When it matters: All colors.
Good value: < 3
Noticeable difference: 1
:
2.78
Gamma
What it is: Brightness of shades of gray.
When it matters: Shadows.
Good value: Between 2.1 and 2.3 (our target is 2.2)
Noticeable difference: 0.1
:
2.22

The out-of-the-box color accuracy of the Samsung C34J791 is decent. The Picture mode with the best results is 'Custom'. Both the white balance dE and the color dE are higher than 3, so most enthusiasts will notice some gray and color inaccuracies. The image has a slight red-yellowish tint due to the slightly warmer color temperature and gamma does not follow closely the target curve resulting in images that are sometimes brighter and sometimes darker than they should be.

9.6 Post Calibration
What it is: Monitor's color accuracy after a full calibration with a spectrophotometer.
When it matters: All graphics and video content on a monitor that has been professionally calibrated.
Score components:
Samsung C34J791/CJ791 Post Calibration Picture Samsung C34J791/CJ791 Post Gamma Curve Picture Samsung C34J791/CJ791 Post Color Picture
Picture Mode
What it is: The picture mode that was used to do the calibration reading. We usually go for the picture mode that gives us the more control over all the picture quality setting.
:
Custom
Luminance
What it is: The luminance at which the calibration was executed. We aim for a luminance level of 100 cd/m².
:
100 cd/m²
Luminance Settings
What it is: The luminance settings, often named 'Brightness' on monitors, usually range from 0 to 100.
:
39
Contrast Setting
What it is: The monitor contrast setting, usually ranging from 0 to 100.
:
100
RGB Controls
What it is: This is the value for each color (red, green, and blue) used in the monitor internal RGB cuts/gains controls. If the monitor does not have an internal RGB cuts/gains controls, then the color temperature setting will be used instead, and the color temperature that gives us the best result will be used.
:
36-40-44
Color Temperature
What it is: The color temperature is a measure of the color of light. A colder color temperature (7000K) will look bluer and a warmer color temperature (4000K) will look yellower/redder. 6500K is the standard color for PC monitors and also for the sRGB color standard.
When it matters: When you care about color reproduction and accuracy.
Good value: 6500K
Noticeable difference: 400K
:
6466 K
White Balance dE
What it is: Average inaccuracy of shades of gray.
When it matters: Overall color temperature of all videos.
Good value: < 3
Noticeable difference: 1
:
0.48
Color dE
What it is: Average inaccuracy of colors.
When it matters: All colors.
Good value: < 3
Noticeable difference: 1
:
0.71
Gamma
What it is: Brightness of shades of gray.
When it matters: Shadows.
Good value: Between 2.1 and 2.3 (our target is 2.2)
Noticeable difference: 0.1
:
2.18

After calibration, the color accuracy is excellent. It is impossible to spot color or gray inaccuracies without the use of a colorimeter as both white balance dE and color dE are well below 1. There is no more red-yellowish tint as the color temperature is corrected closer to the 6500K target and the gamma follows the target curve very closely.

You can download our ICC profile calibration here. This is provided for reference only and should not be used, as the calibration values vary per individual unit even for the same model due to manufacturing tolerances.

8.9 SDR Color Gamut
What it is: The palette of colors the monitor can display
When it matters: General content consumption or production
Score components:
Samsung C34J791/CJ791 Color Gamut sRGB Picture
sRGB xy
What it is: Coverage of the sRGB colorspace on CIE 1931 xy.
When it matters: Almost all content. Includes websites, standard windows environment and SDR movies
Good value: > 95%
Noticeable difference: 5%
:
95.4 %
Samsung C34J791/CJ791 Color Gamut ARGB Picture
Adobe RGB xy
What it is: Coverage of the Adobe RGB colorspace on CIE 1931 xy.
When it matters: Professional photography.
Good value: > 90%
Noticeable difference: 5%
:
81.8 %

s.RGB Picture Mode: Custom (calibrated)
Adobe RGB Picture Mode: Custom

The Samsung C34J791 has excellent coverage of the s.RGB colorspace. However, the coverage of the wider Adobe RGB colorspace might not be enough for professionals in the media and publishing industry.

9.4 SDR Color Volume
What it is: How much of the SDR color spaces the monitor can reproduce
When it matters: General usage and SDR media creation
Score components:
Samsung C34J791/CJ791 sRGB Color Volume ITP picture
sRGB in ICtCp
What it is: How much of the sRGB colorspace a monitor can display at different luminosity levels
When it matters: Most content, including web, SDR video games, and SDR media creation
:
99.2 %
Samsung C34J791/CJ791 Adobe RGB Color Volume ITP Picture
Adobe RGB in ICtCp
What it is: How much of the Adobe RGB colorspace a monitor can display at different luminosity levels, normalized to the monitor's peak brightness.
When it matters: Professional media creation
:
89.5 %

s.RGB Picture Mode: Custom
Adobe RGB Picture Mode: Custom

Excellent coverage of the SDR color volume. The monitor is capable of displaying a wide range of colors in various luminosity levels.

0 HDR Color Gamut
What it is: The monitor's ability to reproduce HDR color spaces
When it matters: HDR content consumption or media creation
Score components:
Wide Color Gamut
What it is: Whether the monitor can support wider color gamuts
When it matters: HDR content and media creation
:
No
DCI P3 xy
What it is: Coverage of the DCI P3 colorspace on CIE 1931 xy
When it matters: When consuming or producing HDR content.
:
N/A
Rec. 2020 xy
What it is: Coverage of the Rec.2020 colorspace on CIE 1931 xy.
When it matters: When consuming or producing HDR content.
Good value: > 90%
Noticeable difference: 5%
:
N/A

HDR is not supported.

0 HDR Color Volume
What it is: How much of the HDR color spaces a monitor can display at different luminosity levels.
When it matters: HDR content consumption and production. Includes streaming services, UHD Blu-rays and HDR games.
Score components:
DCI-P3 in ICtCp
What it is: How much of the DCI-P3 colorspace a monitor can display at different luminosity levels, normalized to the monitor's peak brightness output.
When it matters: HDR content.
Good value: 80%
Noticeable difference: 5%
:
N/A
Rec. 2020 in ICtCp
What it is: How much of the Rec. 2020 colorspace a monitor can display at different luminosity levels, normalized to the monitor's peak brightness output.
When it matters: HDR content.
Good value: 80 %
Noticeable difference: 5 %
:
N/A

HDR is not supported.

7.7 Image Retention
What it is: How much a static image is retained on a monitor screen after a certain amount of time.
When it matters: When working or playing video games on your PC monitor.
Samsung C34J791/CJ791 Image Retention Picture
IR after 0 min recovery
What it is: Image retention measured right after the static image exposure, without recovery time.
When it matters: When changing use or right after changing the type of on screen content (i.e. stopping playing video game to watch a movie).
Good value: 0 is perfect.
Noticeable difference: 0.015%
:
0.14 %
IR after 2 min recovery
What it is: Image retention measured after a recovery time of 2 minutes.
When it matters: When changing use or right after changing the type of on screen content (i.e. stopping playing video game to watch a movie).
Good value: 0 is perfect
Noticeable difference: 0.015%
:
0.00 %
IR after 4 min recovery
What it is: Image retention measured after a recovery time of 4 minutes.
When it matters: When changing use or right after changing the type of on screen content (i.e. stopping playing video game to watch a movie).
Good value: 0 is perfect.
Noticeable difference: 0.015%
:
0.00 %
IR after 6 min recovery
What it is: Image retention measured after a recovery time of 6 minutes.
When it matters: When changing use or right after changing the type of on screen content (i.e. stopping playing video game to watch a movie).
Good value: 0 is perfect.
Noticeable difference: 0.015%
:
0.00 %
IR after 8 min recovery
What it is: Image retention measured after a recovery time of 8 minutes.
When it matters: When changing use or right after changing the type of on screen content (i.e. stopping playing video game to watch a movie).
Good value: 0 is perfect.
Noticeable difference: 0.015%
:
0.00 %
IR after 10 min recovery
What it is: Image retention measured after a recovery time of 10 minutes.
When it matters: When changing use or right after changing the type of on screen content (i.e. stopping playing video game to watch a movie).
Good value: 0 is perfect.
Noticeable difference: 0.015%
:
0.00 %

The overall performance of the monitor in image retention is good. There are some faint signs of image retention immediately after our long exposure test that go away quickly and won't be noticeable in normal content.

8.5 Gradient
What it is: How finely levels of color can be displayed.
When it matters: Details in shadows, sky and skin tones. Matters more for HDR content.
Score components: Subjectively assigned
Samsung C34J791/CJ791 Gradient Picture
Color Depth
What it is: Number of bits per pixel to represent a specific color. Note: we consider 8-bit with dithering to be equivalent to 10-bit, as long as the 10-bit gradient looks smooth.
When it matters: HDR content like HDR video games or HDR UHD movies. Won't matter for regular Blu-ray movies, SDR video game or desktop environment content displayed from a Windows PC. Those are limited to 8-bit color.
Good value: 10-bit.
Noticeable difference: 1 bit.
:
8 Bit

The Samsung C34J791 has an excellent gradient performance. You can hardly notice any banding, as the transition from light to darker shades happens smoothly in almost all colors. This is an improvement compared to the CF791.

10 Color Bleed
What it is: How much the color from one area of the screen affects the color in another area of the screen.
When it matters: All usages, but especially media creation.
Score components:
Samsung C34J791/CJ791 Color bleed horizontal
Pixel row error
What it is: The amount of bleed that appears across the screen horizontally.
When it matters: General usage of a PC monitor, can appear when browsing the web or with media creation like graphics.
Good value: <0.2%
Noticeable difference: 0.1%
:
0.001 %
Samsung C34J791/CJ791 Color bleed vertical
Pixel column error
What it is: Amount of color bleeding that appears across the screen vertically.
When it matters: Most uses of a PC monitor. Can appear while browsing the web or when editing images or graphics.
Good value: <0.2%
Noticeable difference: 0.1%
:
0.001 %

The Samsung C34J791 produces a very small amount of color bleed when it displays large vertical bands of uniform colors. However, it is unlikely that you will notice this during normal usage.

7.5 Reflections
What it is: How much light is reflected by the TV.
When it matters: Bright rooms.
Score components: Subjectively assigned
Samsung C34J791/CJ791 Average room Samsung C34J791/CJ791 Average room off picture Samsung C34J791/CJ791 Bright room off picture

The Samsung CJ791 has good reflection handling. The matte finish diffuses reflections across the screen making them less annoying. However, this does not work very well in a bright room where reflections can become distracting.

8.6

Motion

Score components:

Great motion handling for the Samsung C34J791. It has a fast pixel response time so fast moving objects are crisp with very little blur trail and there is no visible backlight flicker. The CJ791 supports the FreeSync implementation of the Variable Refresh Rate.

8.6 Motion Blur
What it is: The performance of the pixel response time. Poor response time causes trails to follow moving objects. Response time is one of a few sources of motion blur.
When it matters: When there's fast movement on screen, such as during video games and sports.
Score components:
Samsung C34J791/CJ791 Motion Blur Picture Samsung C34J791/CJ791 Response Time Chart
80% Response Time
What it is: How quickly pixels can reach 80% of a full transition from one color to another.
When it matters: When there's fast movement on screen, such as during video games and sports.
Good value: < 8 ms
Noticeable difference: 4 ms
:
4.9 ms
100% Response Time
What it is: How quickly pixels can fully transition from one color to another.
When it matters: When there's fast movement on screen, such as during video games and sports.
Good value: < 20 ms
Noticeable difference: 10 ms
:
14.0 ms
Best Overdrive Setting
What it is: If the monitor has adjustable pixel overdrive settings, which one produces the best response time with minimal overshoot.
When it matters: When adjusting the monitor's settings to get the least possible motion blur.
:
Fastest

Response Time Standard
Response Time Faster
Response Time Fastest

The Response Time 'Fastest' is the recommended setting as it gives the best results. However, in cases where there is a darker background in the image, some blue trail can be seen. If you notice this then switch to the 'Response Time Faster' setting, and this should eliminate the issue.

7.5 Image Flicker
What it is: Luminosity pattern when displaying images
When it matters: Nearly all the time during PC monitor use, but especially during fast movement such as video games
Samsung C34J791/CJ791 Backlight Picture
Flicker-free : No
PWM Dimming Frequency
What it is: Flickering pattern at different luminosities.
When it matters: For people sensitive to flickering.
Good value: N/A or high frequencies (> 300 Hz). Frequencies that are multiples of 60Hz are better.
:
>1000 Hz
Black Frame Insertion (BFI)
What it is: Option to turn screen black between frames
When it matters: Reduces eye tracking blur in motion
Good value: Yes
:
No
BFI Maximum Frequency
What it is: Highest possible frequency of flickering pattern
When it matters: Reduces eye-tracking blur in motion
Good value: Matches the native refresh rate
Noticeable difference: 20 Hz
:
N/A
BFI Minimum Frequency
What it is: Lowest possible frequency of flickering pattern
When it matters: Reduces eye-tracking blur in motion
Good value: 60 Hz
Noticeable difference: 20 Hz
:
N/A

Update 05/16/2019: The dimming frequency field has been updated to include '>1000 Hz' for monitors with high flicker frequencies.

There is no visible backlight flicker. However, at lower brightness levels, the backlight flickers at a frequency of 1260Hz which is very high and it is unlikely that you will notice anything. In the PWM score, we note 0 Hz as the flicker frequency is higher than 1000Hz.

Unfortunately the monitor does not support a Black Frame Insertion (BFI) feature to make the image look crisper.

8.8 Refresh Rate
What it is: How frequently the monitor can refresh and show new frames, and whether it can vary its refresh rate in real time using technologies like G-sync and FreeSync.
When it matters: Mostly for gaming, but does provide a little better motion during normal usage.
Native
What it is: The frequency at which the monitor is capable of displaying images every second
When it matters: General usage, but better results are most important for gaming
Good value: >100 Hz
Noticeable difference: 15 Hz
:
100 Hz
Factory Overclock
What it is: The frequency at which the monitor's can be boosted to using its internal menu.
When it matters: Gaming and other usages where high frame rate content is consumed.
Good value: >100
Noticeable difference: 15
:
N/A
Variable Refresh Rate
What it is: Feature that allows the monitor to synchronize its refresh rate with the input device's output and reduces stuttering and screen tearing.
When it matters: Almost every usage, but is most noticeable in gaming where constant fluctuation in framerate cause distracting artifacts.
:
FreeSync
G-SYNC Compatible
What it is: We test for FreeSync compatibility with an NVIDIA GTX1060. We check for any excess blur, screen blanking, or excess tearing, and confirm the variable refresh rate range.
When it matters: If you have an NVIDIA graphics card.
Good value: Yes
:
Yes
VRR Maximum
What it is: The maximum frequency covered by the Variable Refresh Rate feature of the monitor.
When it matters: Any time the VRR feature is enabled.
Good value: Matches Refresh rate
Noticeable difference: 10 Hz
:
100 Hz
VRR Minimum
What it is: The lowest frequency covered by the monitor's Variable Refresh Rate feature.
When it matters: When using the VRR feature of the monitor at lower frame rates.
Good value: 30 Hz
:
< 20 Hz
VRR Maximum With OC
What it is: The maximum frequency covered by the Variable Refresh Rate feature when the monitor's overclocking feature is used.
When it matters: When both the overclocking and VRR features are used.
Good value: Matching the overclocked refresh rate.
Noticeable difference: 10 hz
:
N/A
VRR Supported Connectors : DisplayPort, HDMI

The Samsung C34J791 has a native refresh rate of 100Hz that is better than the common 60Hz, but not as great as the 144HZ of the higher-end gaming monitors like the ASUS PG279QZ

The monitor supports FreeSync in two modes. The 'Standard Engine' with a limited range of 80 to 100Hz and the 'Ultimate Engine' with a range of 20 to 100Hz.

This monitor is the newer version of the Samsung CF791 and does not have the compatibility issues we encountered with our GTX1060 graphics card and the CF791 monitor.

9.2

Inputs

Score components:

The Samsung C34J791 has an excellent low input lag and a large ultrawide 34'' screen with excellent resolution that favors multitasking. It has two USB-C ports that both support Thunderbolt, although only the one with the 85W sign can be used for charging a Macbook.

9.4 Input Lag
What it is: Delay between input and onscreen reaction.
When it matters: General usage of the mouse and gaming.
Native Resolution
What it is: Lowest input lag possible at the center of the screen, when the monitor is displaying its native resolution at its native refresh rate.
When it matters: General usage and while playing video games.
Good value: < 15 ms
Noticeable difference: 5 ms
:
5.7 ms
Non-Native Res @ Native Refresh
What it is:

Lowest input lag possible at the center of the screen, when the monitor is displaying an alternative resolution at its native refresh rate. The non-native resolution tested depends on the native resolution of the monitor, following this pattern unless otherwise specified in the Input Lag text:

Native Resolution Non-Native Resolution Tested
4k UHD QHD
QHD FHD
FHD 1600x900
3440x1440 2560x1080
2560x1080 1920x1080
When it matters: General usage as well as gaming.
Good value: < 15 ms
Noticeable difference: 5 ms
:
5.8 ms
Native Resolution @ 60 Hz
What it is: Lowest input lag possible at the center of the screen, when the monitor is displaying its native resolution at a refresh rate of 60 Hz.
When it matters: General usage as well as gaming.
Good value: < 15 ms
Noticeable difference: 5 ms
:
5.8 ms
Variable Refresh Rate
What it is: Lowest input lag possible at the center of the screen, when the monitor is using its Variable Refresh Rate feature at its native resolution.
When it matters: General usage as well as gaming.
Good value: < 15 ms
Noticeable difference: 5 ms
:
6.0 ms
HDR
What it is: Lowest input lag possible at the center of the screen, when the monitor is displaying an HDR signal at its native resolution and refresh rate.
When it matters: General usage as well as gaming.
Good value: < 15 ms
Noticeable difference: 5 ms
:
N/A
Black Frame Insertion (BFI)
What it is: Lowest input lag possible at the center of the screen, when BFI is enabled and the monitor is displaying a signal at the highest supported BFI refresh rate.
When it matters: General usage as well as gaming.
Good value: < 15 ms
Noticeable difference: 5 ms
:
N/A

Excellent low input lag and a great improvement over its predecessor the CF791. The input lag remains low even at non-native resolutions (we tested ours at 2560x1080@100Hz), or when the monitor is in VRR mode.

8.8 Resolution and Size
What it is: The number of pixels the monitor can display, and the surface area of its screen.
When it matters: All usages, but especially for office and media editing.
Score components:
Native Resolution : 3440 x 1440
Aspect Ratio : 21:9
Megapixels : 5.0 MP
Pixel Density : 110 PPI
Screen Diagonal : 34.0 inches
Screen Area : 411 sq inches

The Samsung C34J791 is a large 34-inch wide aspect ratio monitor. It has a great 3440x1440 resolution that allows you to easily multitask and place several windows side by side.

Inputs
Samsung C34J791/CJ791 Inputs 1 Samsung C34J791/CJ791 Inputs 2

For the two USB 2.0 ports on the back to work, you must have one of the two USB-C serve as a USB hub downstream. The source will also need a USB-C port for the entire setup to work.

Total Inputs
DisplayPort : 1 (DP 1.2)
Mini DisplayPort : No
HDMI : 1 (HDMI 2.0)
DVI : No
VGA : No
DisplayPort Out : No
USB : 2 (USB 2.0)
USB C : 2 (Thunderbolt 3, USB, PD)
Analog Audio Out 3.5mm : 1
Microphone In 3.5mm : No
Digital Optical Audio Out : No
Analog Audio Out RCA : No

Compared to its predecessor, this monitor supports Thunderbolt through its USB-C connections. Both of them can be used to display video but only the one with the 85W sign can be used to charge a laptop. If the laptop supports Thunderbolt 3 then you can use its USB-C port to send video to the monitor.

Features

The monitor has two internal speakers and is equipped with several additional features.

Additional Features
What it is: Additional features found on the monitor
Speakers
What it is: Whether or not the monitor features standalone speakers.
When it matters: When using your computer without headphones or a dedicated pair of speakers.
:
Yes
HDR10 : No

The monitor has two internal speakers and supports several additional features some of which are:

  • PBP (Picture Besides Picture): In this mode the monitor can display side by side two images from different sources.
  • PIP (Picture in Picture): In this mode the monitor can overlay on the original picture a picture from a secondary source.
  • Samsung MagicUpscale: Is the monitor's function to enhance the details and vividness of lower resolution content.
  • Eco Saving Plus: Is the monitor's function to save power.
  • Game Mode: This setting changes the picture settings like gamma, sharpeness etc., making them more suitable for gaming.

On-Screen Display (OSD)
Controls
Samsung C34J791/CJ791 Controls picture

The controls are the same as the CF791.

In The Box
Samsung C34J791/CJ791 In The Box picture

  • Manual
  • Power brick and Power cable
  • HDMI cable
  • Thunderbolt cable (USB-C)
  • Plastic covers for cable management
  • VESA mount adapter

Differences between Sizes and Variants

The Samsung CJ791 we bought is the 34" model (Samsung LC34J791WTNXZA).

If someone comes across a different type of panel or if their CJ791 doesn't correspond to our review, let us know and we will update the review. Note that some tests such as the gray uniformity may vary between individual units.

Model Size Native Resolution Refresh rate Notes Year
CJ791 34" 3440x1440p 100Hz

FreeSync and Thunderbolt 3 support

2018
CF791 34'' 3440x1440p 100Hz FreeSync support 2016

Note: The CJ791 we purchased was manufactured in August 2018

Compared to other Monitors

Samsung C34J791/CJ791 Group Shot Picture
Left: Samsung CF791. Middle: Samsung CJ791. Right: Asus PG348Q
Unlike our other photographs, this picture wasn't taken under a controlled environment, so do not draw conclusions from it.

The Samsung C34J791 is a large screen ultrawide monitor that is great for gaming. See our recommendations for the best ultrawide monitors, the best gaming monitors, and the best FreeSync monitors.

Samsung C34F791/CF791

The Samsung CJ791 is better than the Samsung CF791. The two monitors have very similar picture quality. The Samsung CJ791, however, has a much lower input lag that makes it more responsive to your actions, and this is great regardless if you're a gamer or not. It also has Thunderbolt 3 support.

LG 32UD99-W

The LG 32UD99 is significantly better than the Samsung CJ791 for most people in the majority of usages. The LG has better viewing angles, due to the IPS panel, better ergonomics, can get brighter, supports HDR and has a 4k resolution. The Samsung CJ791 has a VA panel and slightly better blacks. It also has a faster refresh rate, a lower input lag, and curve profile for those who like it.

Acer Predator Z35P

The Acer Z35P is better than the Samsung CJ791. The Acer Z35P has better ergonomics than the Samsung and allows you to place in a comfortable position with ease. Also, the image remains accurate at slightly wider horizontal and vertical viewing angles on the Acer, although they are still disappointing.

ASUS ROG Swift PG348Q

The ASUS ROG PG348Q is better than the Samsung CJ791 if you care about good viewing angles. The ASUS ROG PG348Q has an IPS panel whereas the Samsung has a VA one. The ASUS also has a faster response time with a smaller blur trail and better ergonomics to position it comfortably. The Samsung CJ791, on the other hand, has a lower input lag which makes it very responsive to your actions.

Conclusion
SEE PRICE
Amazon.com

7.2Mixed Usage
Score components:
The Samsung C34J791 is a decent monitor for mixed usage. It has a large ultrawide screen with ample resolution that favors multitasking but unfortunately, it has poor viewing angles. It is very responsive to your actions but you should avoid placing it in a very bright room as it cannot fight bright room glare.
This is a monitor with decent performance for office use. Its large screen size and great resolution will allow you to do more at the same time, but unfortunately, the poor viewing angles and bad ergonomics will not make it easy to share your work with your coworkers.
The CJ791 is a very good gaming monitor. Its low input lag and excellent resolution and size offer an immersive gaming experience. It supports FreeSync so you can strain your graphics card without worrying about tearing. The fast response time ensures a crisp image with little motion blur in fast action games.
This is a decent monitor for multimedia. The large screen size and excellent resolution enable the monitor to display much of the multimedia content at its native resolution. However, the best picture quality is reserved for those seating directly in front since the viewing angles are bad.
The Samsung C34J791 is a decent monitor for media creation. The large size and excellent resolution are ideal if you open many windows at the same time, but the bad viewing angles and poor ergonomics will trouble you especially if you wish to work side by side with a colleague. However, if you work alone you will appreciate the monitor's responsiveness due to the low input lag and the crisp image thanks to the fast response time.
Unfortunately, the Samsung CJ791 does not support HDR like the Samsung CHG70.

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