by Chris d'Aquin

Created on: March 04, 2008

Remember the good old days of film photography? You would load your cameras with film, shoot 24 or 36 photos and then have to pop the film out and drop it off at a lab. When they were done, you would get a packet of prints along with a sleeve of negatives.

While you might never use the negatives, they were always there just in case you needed to make more prints later. Sure, in the absence of negatives you could make copies from the prints, but it was harder and they never looked quite as good.

With digital cameras, RAW images are the equivalent of "digital negatives" and JPEGs are like the print. What that means, however, is most of us are keeping the prints and throwing away the negatives!

Showing why this is the case will do a good job of explaining the RAW image format and how it differs from JPEGs.

Every digital camera has a tiny little computer processor inside. When the camera is set to save in JPEG format, the processor takes the pure (raw) image data captured by the image chip and processes (or "develops") the photo based upon the camera's settings. It then compresses the result to a smaller size, saves it as a JPEG to the memory card, and throws away the raw image data, never to be retrieved again.

When the camera saves images in RAW format, however, none of the developing and compressing takes place. All of the original image data remains intact. If you want to change the brightness or contrast later, you're working from the original - the digital negative. With a JPEG, all of the items you would tweak have already been processed once and saved, so what you wind up with when you are done is a copy of a copy.

In addition to starting from the pure image data, the tools for processing RAW images are fantastic. Programs like Photoshop give you great control over tweaking the photo's settings, like exposure, color balance, contrast, brightness, and saturation.

Not only does the RAW image store the untouched original image data, it also stores more information per channel, usually at 12 or 14 bits instead of JPEG's 8 bits. Most of this additional information is stored in the brighter tones, so there is more detail in the photo's highlights.

Simply put, for ultimate control and flexibility, shooting in raw format is the way to go.

Before you decide to shoot everything in RAW, however, there are some drawbacks you should consider:

1. Image size - because the image data is untouched and uncompressed, RAW files are much larger than JPEGs. For some cameras they can be 10 times larger, so you will be fitting fewer photos on your memory card.

2. Requires special editing tools - each camera manufacturer has their own unique RAW format, so editing your RAW photos require a program that can read them. Nearly every professional level photo-editing tool will open and process RAW images, but many of the cheaper consumer level programs won't. Before shooting in RAW, make sure the software you use can handle the images. If your favorite editor can't handle them, check the software that came with your camera to see if the manufacturer provided something.

3. More work after taking the photo - because the photos are larger and unprocessed, each RAW image will take longer to open and display on your computer. Every photo worth keeping will also need to be tweaked. Some programs have batch-processing tools, however, to help when a set of photos are practically identical in exposure and color.

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