I am generating a geotiff from a WMS source. I can do so from either PNG requests or JPEG requests. The PNG requests have better contrast but are 4x-5x as slow.
I would like to compare the PNG and JPEG request results for a representative area and develop a contrast correction which I can apply to the JPEG request result to make it look like the PNG request result, but I am not certain how to do this. I can get histograms and stats with gdalinfo. I was thinking perhaps developing a LUT correction which I could then apply, but I'm not sure how to match the images or apply the correction. Other potentially relevant information - The total image size is going to be 350GB-500GB, in a few slices - The WMS server owners are okay with me scraping this, but won't give me the original imagery file - I will be eventually compressing the imagery as JPEG in TIFF - The result will be used by mapserver, then sliced and served as TMS images by mapproxy. If all else fails I can apply a LUT in mapserver. - Screenshots of the jpeg request results vs. png request results are at http://took.paulnorman.ca/images/databc_differences.png. The differences are minimal, but I'd like to do this right I'm after any suggestions for how to derive the adjustments needed as well as how to apply them. Thanks, Paul Norman _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev