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Shooting in the RAW, Perfecting the Image SNAPSHOOTERS don't bother, but serious photographers like to do things the way professionals do: spurning shiny chrome cameras for black, for instance, or lately, setting their camera's menus to RAW. Selecting RAW changes how the camera saves the image, maximizing picture quality and giving the photographer more control over the way the pictures look, but at a sacrifice of some convenience. Most digital photos are saved in the JPEG format, which takes the data from the processor that applies the camera's color and other settings and then discards some data to compress the file to a more convenient size. A RAW image saves the data that goes into the processor, not the data coming out of it, including some the processor might skip, producing clearer and more accurate images. It's a pure record of the pixels captured by the camera's sensor. Working with RAW also allows you to undo mistakes you may have made while shooting. You used indoor light with the camera set for daylight? One mouse click and your computer fixes that. You can even bring out highlight and shadow details that the camera's image processor would have considered too dark or bright to capture. These adjustments don't change the image data, just the instructions for interpreting it. The original RAW image stays intact, so you can rethink and redo your choices. You save the processed version as a new image in the compact but "data shaving" JPEG format or as a TIFF, a memory-stuffing format that preserves everything in the processed image. Instead of obsessing over the size of files, professionals are more likely to be concerned with quality. That's why they love RAW. But amateurs love JPEG, and for the same reason professionals distrust it: data compression. That keeps files small, so your camera's memory card can hold more shots and save them more quickly, and e-mails them without clogging recipients' in-boxes. Fortunately, JPEG compression is selective, weeding out bits you will not miss, so even small JPEG originals look good. The real trouble comes when you edit a JPEG - cropping it, for instance, or fine-tuning color and exposure. Each time you modify and save the image, more data is thrown away. And once the data you wouldn't miss is gone, the compression attacks more noticeable details. Save and resave and save again, and your image can become a blurry, blotchy mess. You can get partly around that by saving a copy of the image as a TIFF, which you can edit safely, or by making all your modifications at once so you resave the file only once. Edit a RAW image all you like, though, and you still have the original to work with. Professionals, especially those in the news media, sometimes use JPEG anyway, for speedy operation and insurance against running out of memory-card space. And shots that originated in other formats are often copied as JPEG's after editing for fast transmission. (Many of the photos in this paper were received that way.) When image quality counts more than file size, however, RAW is the way to go. Most cameras that produce RAW image files come with computer programs that can read them, apply your choice of settings and save them as TIFF or JPEG files. But more versatile third-party programs like Paint Shop Pro, Photoshop Elements and iPhoto began supporting RAW only recently. And because camera makers are rarely free with information on their formats, Adobe has developed DNG, a "digital negative" format, which anyone is free to use.
http://www.nytimes.com
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