By Andrew Hudson Published: June 7, 2011 Updated: November 17, 2016
RAW is one of those subjects that, if you have to ask, you don’t need it. If you are the sort of person that would benefit from using raw files then you already know what they are.
Raw is not a particular format but a general term to mean the native information file. You are getting it “raw” from the image sensor.
Digital cameras do post-processing internally, to tidy up the file, sharpen it, and convert it to JPEG format. But for people who want to that processing themselves, the camera can output the “raw” data.
The format of raw files is proprietary to each camera manufacturer. Canon files are .crw or .cr2, and Nikon files are .nef or .nrw (Panasonic conveniently uses .raw). Because the files are proprietary, you need licensed decoder software to read the files. Some high-end image editors such as Adobe Photoshop and Apple Aperture are able to decode the most popular raw files.
Benefits of RAW
“Unlike JPEG, RAW is a lossless format, meaning that information is not lost during the process. By shooting in RAW and putting off saving to JPEG until the final stage of the process, you will conserve as much information as possible throughout your workflow.”
“Why is RAW better quality? RAW data from most DSLR cameras contains 12 bit data, which means that there can be 4,096 different intensity levels for each pixel. In an 8-bit JPEG file, each pixel can have one of only 256 different intensity levels. This means you can manipulate a RAW file to a greater extent without degrading the quality.”
— Hilary Quinn, for Shutterstock
“If you are using JPEG, always proceed carefully. Every time you make a change to the file there is a chance that you will introduce compression problems and its important that you can go back if you make adjustments that damage the file. Basically, when working with an 8-Bit JPEG file any severe editing of the contrast, saturation, colours, or detail sharpening can introduce artifacting.”
The benefit of raw files is that you receive all the image data available. JPEGs have to throw away some data to fit the standard. So if you’re a “tweaker” that likes to get the most out of Photoshop, then raw is what you want.
Benefits of raw files can include:
- Wider colorspace
- Wider dynamic range
- No compression artifacts
The price you pay for raw files is file size — the data demands are huge. You save less images on each data card and hard drive, and the files take longer to transmit. So if you’re traveling with limited equipment, or transmitting files via FTP, this is an issue.
Microstock agencies and many printers do not accept raw files. So, after finishing your Photoshop masterpiece, save the file as a TIFF and/or JPEG.
Want the best of both worlds? Then set your camera to output both versions. Each image is saved in two files — one raw and one JPEG.
“The main advantage of the RAW format [over JPEG] is that you never lose the original information and can always go back. If artifacting happens during editing or saving, the original file is still there and you can start over without completely losing the image.”
Because raw files are proprietary, you are at the whim of the provider. In the future, the format you are using may stop being supported and your images would be unreadable. So ensure that you resave each raw file in something standards based. The U.S. Library of Congress recommends three formats for photos: JPEG, TIFF and DNG.
Adobe has offered a common raw format, named NeGative. You can use this as an intermediate format for saving images.
This is a Photoshop format and can contain much more editing information than is needed for a photo.
Image Requirements: File Format
iStock accepts RGB JPG files only. TIFs, PNGs and PSDs will be declined. CMYK images will also be declined.
This is an old Microsoft Windows format. Use JPEG instead.
Bitmap and Vector
These are not formats but types images encoding techniques. Photos are bitmap images, whereas graphics are usually vector-based. Bitmaps describe each individual pixel, so they have a limited resolution. Vectors are equations that connect point A to point B and can be scaled to any size.
RGB and CMYK
These are not file formats but refer to the colorspace — how the color information is stored. RGB (for Red Green Blue) should be your choice, because it is wider than CMYK and used for media such as websites. CMYK (for Cyan Magenta Yellow and blacK — as B could mean Blue) is used for four-color printing, which can be printer specific.
Gosh I ramble on. You must be the only person to read this far.