Updated

Our Scanner Score and Tests
Printers

What it is: All-in-one printers usually have a scanner, which is used to digitize documents or photos.
When it matters: When you want a scanner with your printer.
Score distribution

If you've ever needed to copy chapters of a book for a report, scan an old family photo to put in your scrapbook, or fax medical documents to your doctor, then you know how frustrating not having a scanner on hand is. While many printers these days come with an integrated scanner, they're not all created equal.

We test the different scanning abilities of each printer we review so you can find something with the right scanning features for your needs.

We first look at whether the printer has a scanner. If it does, we check whether there's a flatbed scanner, sheetfed scanner, or both. If there's a flatbed scanner, we determine the largest media format it can scan. If there's a sheetfed scanner, we check whether it has an Automatic Document Feeder (ADF) and if it does duplex scanning. We then look for the highest possible scan resolution and output color depth. Lastly, we check whether the printer has a fax or copy feature.

Note that we currently don't perform any objective tests on the scan quality itself - at the moment, we only report the printer's available scan options and specifications.

Test results

Our tests

Epson ENVY Photo 7855 flatbed scanner

 

Scan Flatbed

What it is: Scanning the document using the flatbed glass.
When it matters: When you only want to scan single pages or photos.

If you want to scan delicate documents like photographs or old letters, or thicker objects like ID cards, passports, or books, then you need a flatbed scanner.

Just like the name suggests, a flatbed scanner has a scan head placed underneath a flat bed of glass or clear plastic, as pictured in the Brother HL-L2395DW here to the right. You place the document you'd like to scan on top of the flatbed, and the scan head moves beneath the glass to capture your document.

However, having a flatbed usually makes the printer fairly wide, since it needs to be large enough to accommodate at least an 8 1/2" x 11 sheet of paper. It can also take a long time to scan multiple documents in a row using the flatbed. That said, it usually provides higher quality scan options to choose from than a sheetfed scanner. In addition, it's also often possible to scan thicker documents, like magazines, or even textbooks if the flatbed cover has expandable hinges.

Scan Sheetfed

What it is: Scanning documents from the sheetfed paper tray; this is usually located on top of the printer.
When it matters: When you need to scan whole documents; you can place the documents and let the printer handle the rest.

If you want to quickly scan sheets of plain paper, a sheetfed scanner is a good feature to have, especially if it also has an Automatic Document Feeder (ADF).

This type of scanner captures documents fed through a dedicated input tray. The scanner head moves from side-to-side inside the sheet feeder to scan the page as it passes through the feeder. The document is ejected once it's done scanning.

Some printers only have a sheetfed scanner, like the HP Deskjet 3755 pictured here to the right. Since they only need to be large enough to accommodate the width of a sheet of paper, they're usually smaller than printers with a flatbed scanner. However, sheetfed scanners are prone to paper jams, so they're not recommended for scanning more fragile documents, like photos.

Automatic Document Feeder

What it is: Usually using the sheetfed, it's the possibility to scan a whole document automatically. The printer will automatically select the next page to scan.
When it matters: When you frequently scan documents with three or more pages.

If you often tend to scan multiple sheets of paper at a time, an Automatic Document Feeder (ADF) is a must.

An ADF automatically feeds through multiple sheets of paper into the sheetfed scanner. This means that instead of having to feed each page of a document to the scanner yourself, you just set them all in the input tray, hit start, and the ADF handles the rest.

An ADF needs a sheetfed scanner, so if the printer only has a flatbed scanner, then it gets automatically gets a "no" for the Automatic Document Feeder test. While most sheetfed scanners have an ADF built-in, not all do. To confirm, we try and scan a multi-page document with the sheetfed scanner. If it processes all the pages automatically in one single operation, then it gets a "yes" in this test.

Duplex Scanning

What it is: The ability to scan two-sided documents.

If you regularly need to scan significant quantities of double-sided documents, you'll want to make sure your printer's scanner supports duplex scanning.

Duplex scanning is the ability to scan both sides of the same document without having to flip the page over yourself. There are two types of duplex scanning. A Reversing Automatic Document Feeder (RADF) captures one side of a document, flips it over, then scans the other side. A Duplexing Automatic Document Feeder (DADF) scans both sides at the same time. While we don't currently test duplex scanning types, DADFs are generally much quicker.

Duplex scanning requires an Automatic Document Feeder (ADF). If the printer doesn't have one, then it automatically gets a "no" for the Duplex Scanning test. If there's an ADF, we look for a scanning option for duplex printing and try to scan a two-sided document to see if it does indeed capture both sides automatically. If it does, then it gets a "yes" in this test. However, if it prompts the user to flip the document over manually, then it gets a "no", even if the feature is listed as a duplex mode.

Scan Resolution

What it is: The resolution in DPI (dots per inch). This is an indication of the level of detail the scanner can achieve.
When it matters: When you want to do high-quality photo scans or photo enlargement and need a higher resolution.
Good value: > 300 dpi
Score distribution

If you need to scan artwork, photographs, or other forms of highly detailed media to make printed copies afterward, you'll want to keep an eye on the scan resolution.

Scan resolution is the level of detail a scanner can retrieve from a physical image. This is measured in DPI, or "dots per inch": the more dots you scan per inch, the more detail your digital image will have. An image scanned at a lower resolution will have less detail than one scanned at a higher resolution. However, a higher scan resolution isn't always better: a high DPI increases the time it takes to scan an image considerably. It also results in a larger file that some computer programs can't handle.

To test the scan resolution of a printer's integrated scanner, we check the provided scanning software and report the highest scan resolution indicated.

Scan Color Depth

What it is: The color information that the scanner gathers while scanning a document or a photo. A 24-bit scanner scans 256 colors per 8-bit channel, for a total of over 16 million scanned colors. A 48-bit scanner scans 65,536 colors per 16-bit channel, for a total of over 281 trillion colors.
When it matters: When true color is important while scanning your favorite photo. More than 24 bits is for very specific photo printing use.
Good value: 24 bits
Score distribution

If you do any professional photo retouching or editing work, then you'll want a scanner with good color depth.

Color depth is the amount of color information a scanner can retrieve from a physical image. This information is measured in bits. Three color channels work together to create your images: red, green, and blue. Most scanners retrieve equal amounts of information from all three channels, so a 24-bit scanner gets 8 bits of color information from each channel, while a 48-bit scanner retrieves 16 bits from each one. For most people, a 24-bit scanner is more than enough. However, if you work with photo editing software, then you might need more information for your images to process smoothly. Scanning in 48-bit creates massive files, though, so it's important to weigh the pros and cons.

To test the color depth of a printer's integrated scanner, we browse the user guide and report the highest color depth indicated. If it's not mentioned in the user guide, we check the provided scanning software. It's also worth noting that there can be differences between a scanner's raw input, and what it can output in terms of color depth. Some scanners say they scan in 48-bit, but the resulting file is converted to 24-bit. We only report the output, or external color depth.

Flatbed Scan Size

What it is: The largest format the flatbed can accommodate for a scan.
When it matters: If you plan on scanning something larger than the typical letter format (8.5" x 11").

If you need to be able to scan larger legal documents or small posters, then you'll want a scanner with a larger flatbed.

Most integrated flatbed scanners in a printer are limited to letter-sized documents (8.5" x 11"). However, some can scan larger sizes, such as legal (8.5" x 14") or tabloid (11" x 17"), like the Epson WorkForce WF-7720.

Fax

What it is: Whether there's a fax feature or not.

If you need to correspond with a medical clinic, insurance bureau, or government office, then you might need to do so by fax. If so, having a printer with integrated fax can be very helpful.

Although it might seem like a thing of the past, many businesses, and even certain individuals, still depend on fax technology to send important communications quickly and reliably without needing the Internet. Usually, when you fax a document with an all-in-one printer, the scanner captures the data, digitizes it, and encodes it so it can be sent through the phone line. The receiving fax machine decodes and reassembles the scanned document onto a sheet of paper.

We check each printer we test for the presence of a fax feature. While there are different fax technologies available, such as Fax over IP which eliminates the need for a traditional phone line, we currently don't specify which technology is used - we only report whether the printer has a fax feature or not.

Copy

What it is: Whether there's a copy feature or not.

If you often need to photocopy book chapters for class, or business documents to bring with you to the boardroom, then you'll want a printer that has a copy feature.

Copying documents with an all-in-one printer is pretty straightforward. The scanner takes a digital image of your document, and the printer reproduces it onto a sheet of paper. If there's a flatbed scanner, you can copy pages from a magazine or book. If there's a sheetfed scanner with an Automatic Document Feeder (ADF), you can quickly copy multiple documents in a row.

We check each printer we test for the presence of a copy feature. More often than not, if a printer has an integrated scanner, it can produce photocopies as well.

Additional Information

Scan Resolution

Scan resolution is the amount of detail a scanner creates as it generates a digital file from a physical object. This is measured in DPI, or "dots per inch", where one physical scanning "dot" equals one digital image pixel. As a result, the term DPI is often used interchangeably with PPI, which means "pixel per inch". However, digital images don't have actual physical dimensions, so the PPI is often expressed by pixel dimensions. These dimensions depend on the size of the physical image that was scanned, as well as the DPI/PPI it was scanned at.

For example, a 4" x 6" image scanned at 300 DPI will generate a 1200p x 1800p file. You can find the pixel dimensions of a digital photo in most photo processing software programs.

Printers work by spitting thousands of tiny dots onto a sheet of paper, so they also calculate their print resolution in DPI. This means it's possible to calculate the optimal DPI you need to scan an image at if you know what size you want to print the resulting file at. Larger prints require more pixels, so if you're scanning images with the intent to reprint them in a larger format, it's important to be mindful of your scan DPI.

Taking the example from before, if you scan a 4" x 6" photo at 300 DPI, then print it in an 11" x 17" format at 300 DPI, it won't be very detailed. Even though the scan and print DPI are the same, the image will look blown out and pixelated. This is because the pixel dimensions of an 11" x 17" print at 300 DPI are 3300 p x 5100p, which is larger than what you scanned at. To create a nice, detailed, enlarged 11" x 17" copy of your 4" x 6" photo with a 300 DPI print resolution, you'll want to scan it at around 900 DPI instead.

That said, the higher the DPI, the longer the scanning time and the larger the resulting file. This means a higher DPI isn't always better. For example, an image scanned at 1200 DPI can create a file that is so large that some programs won't even be able to open it. A scan resolution of 300 DPI is usually more than enough for letter-sized documents while you generally shouldn't need more than 600 DPI for photos, unless you're intending to enlarge them significantly.

Color Depth

Digital photos are composed of three color channels: red, green, and blue. When these three RGB channels are added together, they can create the full color spectrum. Color depth is measured in bits, as a bit represents a single unit of information. So the more bits a scanner assigns to each channel, the more color information is retrieved. Most scanners assign 8-bits of color to each channel. These scanners are often called 24-bit scanners, since 8-bits per channel results in 24 total bits of scan information.

Each 8-bit channel retrieves 256 different shades of the associated color, so 256 different shades of red, green, and blue for a total of 16,777,216 distinct colors. While this is more than enough for the human eye, sometimes it's not sufficient for a computer when running a photo manipulation or editing program. When different photo editing effects are applied, if there isn't enough information in the file for the program to execute its command, it will often 'clip out' certain ranges of colors and shades so it can continue processing the image. This can make an image look less smooth.

To compensate for the issues associated with 24-bit scanning, certain scanners assign 16-bits of information to each RGB color channel. The resulting 48-bit files have tons of information that helps mitigate the effects of clipping when performing intensive photo editing tasks.

However, like scanning at a higher DPI, scanning with a higher color depth has its drawbacks. Files scanned with a 48-bit color depth are massive, which makes them very slow to render, even with a fairly powerful computer. They're also limited to the TIFF format, which isn't supported by all computer programs, unlike JPEG, which maxes out at 24-bits.

What's Missing?

There are a few things we don't yet test, like:

  • Flatbed scanner type (CIS vs CCD)
  • Internal (input) vs external (output) color depth
  • Color accuracy
  • Dynamic range
  • ADF scanning speed
  • Duplex scan type (multi-pass RADF vs single-pass DADF)
  • Software (OCR, receipt categorization, barcode recognition, image enhancement, etc.)
  • Driver support (WIA, TWAIN, ISIS, etc.)
  • Different fax transmission options (FoIP, online fax service, etc.)

Conclusion

A scanner is a useful tool for those who require more versatility from their printers. Depending on what you need to scan, you might want to look for a particular kind of scanner. A flatbed scanner is ideal for preserving photos or making copies of your passport, while a sheetfed Automatic Document Feeder (ADF) is perfect for photocopying tax forms. While scan resolution and color depth likely won't matter much to the average family, professional photographers, digital artists, and designers will want to keep an eye out for something with a high max resolution and color depth.

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