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Why RAW?
Authored by: goatbar on Mar 15, '05 01:10:28PM

Hi All,

Could someone please explain to my why everyone is so excited about the RAW format? Why not use 16bit per channel tiff with lossless compression? Any if you need to save all the camera parameters, there can be tags for just about anything. Tiff can even save multiple frames in a file so you could save a dark current image and a list of bad pixels. Wasn't this the whole idea of a tagged image file format (tiff)? Also, you could easily save raw dn levels in a tiff plus the color response functions.

Please set me straight!
Thanks,
kurt



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Why RAW?
Authored by: lrosenstein on Mar 15, '05 01:54:35PM

RAW format captures all the information the camera has without any processing. Most cameras only capture one color channel per pixel. Producing even a 16-bit TIFF from that would require some processing in the camera.

You are right about the flexibility of TIFF, and in fact Adobe's new digital negative format is based on the TIFF standard.



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Why RAW?
Authored by: goatbar on Mar 15, '05 02:11:28PM

That makes sense. THANKS!



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Why RAW?
Authored by: Bruce Miller on Mar 15, '05 02:13:07PM

Any alteration to an image file is always destructive, especially color corrections, there is less information in the resulting file. The smaller the original file, the worse the effect (banding, posterization,) on edited output.

RAW color correction is lossless, one can even shoot grossly misadjusted color settings (tungsten shot as daylight) and recover the color as long as exposure is within parameters.



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Why RAW?
Authored by: HAL9000 on Mar 15, '05 08:12:13PM

Just to reiterate / elaborate on what the others have said, tiff files are stored after the camera has done some processing to the image, such as color balance, etc. RAW files are stored before the camera does anything to them except record them. Thus, if you trust youself to make color and sharpening corrections more than you trust your camera, RAW is useful because you're not relying on the processing power of the camera, which is likely to be not as good as the results you can get from a computer and some photoshop skill. So usually if you're talented at photoshop, or have some program that is better than the internal devices in the camera, then RAW is more useful than TIFF. But if you're not all that experienced, it can often be a good idea to let the camera do it for you.



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