----- Original Message ----- From: "Robert M." <[EMAIL PROTECTED]> I agree with you on all the items in your email. I am not sure what you suggest in the above paragraph, though. Are you saying that Canon actually stores all 3 color components for each pixel, i.e. they already interpolate the missing color information, and then store this image in a regular lossless compressed tiff format embedded in their raw files? I THINK this is not what Canon is doing. The reason is that the file sizes seem too small for this to be true. If you lossless compress a typical image the compression rate is usually less then 2 even when using fairly sophisticated algorithms. The raw files from Canon are considerably smaller then that even taking into account all the other information you mentioned above, i.e. SensorSize*12bits*3/Raw image size > 2.
My GUESS is that Canon might use a compressed TIFF format on the luminance data for each channel, i.e. a gray-scale image and add all kinds of information to it. Basic processing like dark current correction, compensation for non-linearity, etc. is already done before the file is compressed. In any case, if you find that information about the Canon raw format I would be very interested. -- Me, too, 'cause I don't think the above is correct either. My guess, since we are guessing, is that a RAW file is simply a LZW compressed TIFF that has not had all the camera settings applied. Let's break it down into the simplest terms. - The sensor captures the RAW RGB data. - The sensor interpolates the image to create all the missing red & blue color (I think green has the most pixels, can't remember). - The camera applies tone curves to the image for ISO & white balance etc. - The camera saves the image as RAW, RAW + JPG, or JPG. So, a RAW file would be the RAW RGB data captured by the sensor along with, but separated from, all the camera settings. Just my guess ... Mike * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
