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Photoshop® CS4 Bible by Dan Moughamian, Simon Abrams, Stacy Cates

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4.1. The RAW Format

As mentioned before, RAW files are unprocessed — they contain all the image data that was originally recorded by the camera's sensor in its uncompressed, unaltered form. To get a little technical, the information is actually recorded as a grayscale image, along with a pixel-by-pixel map that corresponds to the color information in the photograph. As a result of all this information, RAW files are generally quite large in terms of size and will quickly fill up your camera's memory card, as well as your computer's hard drive.

Some of you might ask, "Well, what's the point of going through all this, if I can just set my camera to JPEG mode and be ready to go?" After all, JPEG does have its advantages:

  • It requires no extra processing.

  • It is an almost universally readable format.

  • It can do a fantastic job of compressing photos to file sizes that are a fraction of their RAW equivalents, all the while retaining gorgeous, sharp, color detail.

You wouldn't be alone in questioning the use of RAW. In fact, this debate continues to rage in photo-related discussion forums across the Internet. To help you decide between RAW and JPEG, here is a scenario to consider. Let's say you left your camera on the default JPEG setting that it was on when you pulled it out of the box. The moment you squeeze the shutter, your camera (helpful and well-intentioned gadget that it is) applies a series of adjustments to the data it captures, based on some pretty clever methods for evaluating ...

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