The gods who rule the imaging world must love different file formats, because they have created so many of them. There are dozens of graphics formats supported by image editors like Photoshop that are so far off the radar that simply mentioning them is an exercise in trivial pursuits. Who reading this book has used .IFF (Amiga), .TGA (Targa), .PXR (Pixar), .PX1 (PixelPaint), .PIC (SoftImage), or .RLA (Wavefront) formats?
Of course, the main reason digital cameras offer more than one file format in the first place is to limit the size of the file stored on your memory card. If a digital camera had unlimited memory capacity, and file transfers from the camera to your computer were instantaneous, all images would probably be stored in RAW or TIFF format, with RAW preferred when post processing of the image was likely, and TIFF gaining the nod for convenience and ease of use and because not all applications can interpret the unprocessed information in RAW files. (I'll explain the difference between RAW, TIFF, and JPEG later in this chapter.) Both RAW and TIFF store the image as you took it, with no noticeable loss in quality.
JPEG exists because a more compact file format is needed that can store most of the information in a digital image, but in a much smaller size. Unfortunately, JPEG provides smaller files by compressing the information in a way that loses some information. JPEG is a viable alternative because it offers several different quality levels. At the highest quality level you might not be able to tell the difference between the original TIFF file and the JPEG version, even though the TIFF occupies, say, 14MB on your memory card, whereas the high-quality JPEG takes up only 4MB of space. You've squeezed the image 3.5 times without losing much visual information at all. If you don't mind losing some quality, you can use more aggressive compression with JPEG to store 14 times as many images in the same space as one TIFF file.
RAW exists because sometimes we want to have access to all the information captured by the camera before the camera's internal logic has processed it and converted the image to a standard file format. RAW doesn't save space, nor does it provide intrinsic higher quality than, say, a TIFF version. Think of your camera's RAW format as a photographic negative, ready to be converted by your camera or, at your option, by your RAW-compatible image-editing/processing software.
Of course, the main reason digital cameras offer more than one file format in the first place is to limit the size of the file stored on your memory card. If a digital camera had unlimited memory capacity, and file transfers from the camera to your computer were instantaneous, all images would probably be stored in RAW or TIFF format, with RAW preferred when post processing of the image was likely, and TIFF gaining the nod for convenience and ease of use and because not all applications can interpret the unprocessed information in RAW files. (I'll explain the difference between RAW, TIFF, and JPEG later in this chapter.) Both RAW and TIFF store the image as you took it, with no noticeable loss in quality.
JPEG exists because a more compact file format is needed that can store most of the information in a digital image, but in a much smaller size. Unfortunately, JPEG provides smaller files by compressing the information in a way that loses some information. JPEG is a viable alternative because it offers several different quality levels. At the highest quality level you might not be able to tell the difference between the original TIFF file and the JPEG version, even though the TIFF occupies, say, 14MB on your memory card, whereas the high-quality JPEG takes up only 4MB of space. You've squeezed the image 3.5 times without losing much visual information at all. If you don't mind losing some quality, you can use more aggressive compression with JPEG to store 14 times as many images in the same space as one TIFF file.
RAW exists because sometimes we want to have access to all the information captured by the camera before the camera's internal logic has processed it and converted the image to a standard file format. RAW doesn't save space, nor does it provide intrinsic higher quality than, say, a TIFF version. Think of your camera's RAW format as a photographic negative, ready to be converted by your camera or, at your option, by your RAW-compatible image-editing/processing software.
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