Hi Chris, 1. "Which contrast formula do you plan to use, and how does it need a histogram exactly? I imagine exposing the contrast function parameters to the user rather than choosing them automatically."
The contrast algorithm for color images needs histogram equalization, and that needs histograms calculations. Can't say now if there will be parameters, since histogram equalization is like an automatic enhancment with no parameters. There are parameters for the grayscale version though. Will deal with this when time comes. 2. "It looks pretty nice. Without knowing what it's used for it's a bit difficult to know whether it will do everything we need." It is just an analysis tool, like in Photoshop. A channel's histogram tells you distribution of intensity values. You can spot many bad things in the image by looking at the histogram. So, that is all this function will do, it will just calculate a histogram that you can see(once it is drawn by another function), but you can't manipulate it in any way. 3. "I assume you mean to produce an image of the 2D graph of count vs intensity from oiiotool?" Here is an example output from the histogram_draw function I have: http://postimage.org/image/pwlx0tsbr/ The histogram function calculates the histogram in std::vector, and the histogram_draw function takes that vector and "draws" it in an ImageBuf. I separate the calculation and drawing in two functions. 4. "The problem with doing that is you're limited to simply eyeballing the data and it's a bit hard to process it any further. In oiiotool, maybe it would make more sense to produce a 1D image as a result (not in the basic API though - the std::vector is good there), with the option of writing the image values directly to stdout from oiiotool for further processing?" That would be awesome, will do it. Not so much for visualizing, we will be able to do that with the histogram_draw function. More for the processing side, for some reason you might want to take that data to other app. I will send the histogram_draw function soon, it will make more sense when you see them together. Stefan
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