EOS D30 Software Starter Guide

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About the RAW Image Format
The camera uses two standard image file formats: JPEG and RAW. In JPEG mode,
the camera processes images after capturing them to produce optimal results.
With this format, images are compressed so more can be stored on a single CF
card. However, the compression is irreversible, meaning that the original image
data cannot be recovered after processing. In contrast, the RAW format records
the image data as captured by the camera’s CMOS without further processing.
RAW images are compressed, but the compression is reversible so that a high-quality
image can be obtained from the decompressed file without any loss of image
quality. Although a RAW file is larger than an equivalent JPEG file, it is still only
approximately one-third the size of an uncompressed file (RGB TIFF), making it
relatively compact.* Please see the Camera User’s Guide to learn how to set the
camera to shoot in RAW mode.
The process of obtaining a high-quality RGB signal from a RAW image is called
“conversion.” Even if you use ZoomBrowser EX or the TWAIN Driver to adjust the
image quality of the original image data in some way, the image retains its original
high quality. In contrast, other standard uncompressed file formats, such as RGB TIFF,
are processed in the camera and further processed by the retouching software,
which reduces the image quality.
Please note that the ZoomBrowser EX or the TWAIN Driver programs are required to
open or adjust RAW images on a computer.
* As measured by standard Canon test conditions.