I'll Take My Photos RAW Please!

This entry is about how your camera saves a file to the memory card when you take a photo.

I'll try to keep this at the most basic level possible. This blog is intended to help new comers to photography, and I don't want to scare you away from the post with a load of technical jargon and somewhat unpractical information.

There are 3 basic options for saving your image to the card in most modern DSLR cameras. These options are:

JPG

RAW

RAW + JPG

What is a JPG(JPEG), and what is a RAW?

For starters, the image sensor in the average DSLR is gathering information in either 12 or 14 bits of data. Basically this allows the camera to save between 4,096 and 16,384 brightness levels depending on whether it's a 12 or 14 bit camera.

A JPG file is a standard image format that saves the file with lossy image compression. What this means is that of the 4,096 - 16,384 brightness levels available from your cameras sensor, the image is compressed to reduce the file size down to 8 bits of data which equivocate to 256 brightness levels. Additionally, all the saturation, contrast, white balance data, sharpening levels, and other camera settings are permanently assigned to the file.

The photo at the top of this post is a side by side comparison of what happens as a photo becomes compressed. The photo on the left is a JPEG file with some compression. As the photo is edited multiple times and re-saved multiple times, the compression becomes more and more apparent by artifacting (image quality loss due to compression) as seen in the right hand photo. Both versions of the photo show some compression artifacts upon careful examination, but the one on the right is far more degraded. It's easiest to notice the artifacts in the sky area of the photo.

A RAW file is an image format that saves the file with no compression or lossless compression (compression with no quality loss). RAW files save all the data originally taken from the sensor so that in the final file, one has the full 12-14 bits of data to play with. This allows you to change the exposure to a further degree after the image is already taken because instead of only having 256 brightness levels, you have up to 16,384 levels to play with. The settings you have in the camera at the time the photo is taken is saved to the file as well, but it doesn't save ONLY that information like JPG's. It saves all the other information available as if you had shot the photo with different settings.

For example, if you had shot a photo in JPG and the Shade white balance setting was chosen, you would be essentially stuck with that choice forever in the JPG file. If you shot the photo in RAW, you can go back and choose any of the white balance settings that were originally available to you at the time the photo was taken.

Let me interject that I'm not advocating using RAW as an excuse to not set the correct setting from the get go. I am saying, however, that if you do make a mistake, you have the chance to save the photo by changing the original settings slightly to salvage what would have been unsalvageable before RAW came along.

The more you get right on camera, the less work you have to do in post processing. When you shoot a wedding with 100-200 keepable photos, you don't want to have to edit every setting in post processing. This will add a lot of time to your processing work, whereas you could have saved loads of time by taking a few extra seconds at the time of the shoot to get the settings right.

The above options for saving a file are pretty self explanatory. If you choose JPG in your camera menu, the photo will be written as a JPG. If you choose RAW, the image will be saved as a RAW. The third option is to shoot in RAW & JPG, essentially saving 2 copies of each photo to the memory card, 1 in each file format.

Additionally, when you convert the RAW file into a TIFF file or a PSD file in photoshop or other image editing program, it is able to spread the 12-14 bits into 16 bits of information, or 65,536 brightness levels to work with.

A JPG file will often look just as nice in print as a RAW file converted to TIFF or PSD would have. The difference comes with the pros and cons listed below.

PROS & CONS

JPG PROS

• Smaller file size aka fit more files on memory card
• Shoot photos faster on camera because the small file size allows the images to be written to the card much faster
• If you don't like to do a lot of post processing to your images, the JPG file will eliminate much of the post processing work

JPG CONS

• Smaller file size from compression causes JPG artifacts (a noticeable image quality loss)
• Every time you re-save your JPG after editing it, the file is further compressed and the image quality gets worse and worse due to increasing compression artifacts.
• Lose most of the ability to recover under or over exposed photos.
• Can't change white balance after the fact, which can make a photo very unusable if you had a very wrong setting in camera.

RAW PROS

• Ability to bring change white balance after the fact
• Ability to recover detail from blown highlights and underexposed shadow areas
• No quality loss due to compression (no artifacts)
• Larger range of color data available to you in the 12 or 14 bit RAW file.

RAW CONS

• Larger file size
• Slower writing to memory card, therefore reducing how rapidly the camera can fire shots
• More post processing work

Different camera companies use different file extensions for RAW formats. For example, the Canon brand uses .CR2 file format in many of its cameras, whereas Sony uses .ARW. The RAW format has not been standardized into one file extension yet. The downside to this is that, one RAW converter (a program that converts your RAW to .JPG, .TIFF, .PSD, etc) won't necessarily be able to open up and edit all RAW file types. The good news is that your camera likely came with a converter for its associated file format. Additionally, Adobes latest Photoshop products like Photoshop CS4, Adobe Photoshop Lightroom 2, etc, have the ability to read and edit most RAW formats from across the board. The program built into these products is called Adobe Camera RAW. It is even downloadable for many of the older versions of Photoshop that didn't originally include the feature. It is also worth mentioning that even though there isn't one file format directly from the manufacturers, Adobe Camera RAW lets you optionally convert the original RAW file to a .DNG raw file(Adobe's RAW file format). This file format, similar to the .PNG file will likely maintain support by Adobe for many many years to come, whereas your native file format may lose support as new formats come out in the future.

To wrap this up, I just want to add that shooting RAW may not be the right choice for everybody. It sure can save your butt when you have a paid photo-shoot, and for whatever unexpected and unexplained reason, you botched the shoot and under exposed all the photos or had a terrible white balance setting. You'll likely be able to fix your mistakes and your customer will have a nice series of photos in there photo album for years to come.

I hope you have a better understanding of the common file formats as this has been RAW files "From The Ground Up!"