Name | Modified | Size | Downloads / Week |
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shiftwb.c | 2014-10-09 | 6.7 kB | |
README | 2014-10-09 | 2.5 kB | |
LICENCE.txt | 2014-10-09 | 35.1 kB | |
Totals: 3 Items | 44.4 kB | 0 |
SHIFT WHITE BALANCE UTILITY Copyright 2014 Andreas Soupianas. Licence: GPL This is a simple utility for photographers to shift white balance of jpeg images taken with nikon cameras and perhaps other brands too. When we use raw format we can specify the white balance color temperature. However when we shoot jpeg, if we select the wrong white balance it is not so easy to fix later. This utility is based on a test, and the data it uses are extracted from photographs taken with various Kelvin temperature white balance settings. Nikon cameras write exifdata on jpeg specifying the Red and Blue Balance. The utility can extract these numbers if exiftool is installed. REQs: C compiler. cjpeg & djpeg to read and write the jpegs. exiftool if you want to read inkelvin from the file (not needed but helpful). COMPILE: cc shiftwb.c -o shift_wb INSTALL: copy shift_wb somewhere in your path USE: shift_wb inkelvin infile outkelvin outfile [clipscale] If you know what color temprature you used when you took your photograph, thats what you put as value for inkelvin. If you dont know the color temperature you used, you can specify f and shift_wb will try to extract that information from the jpeg file through exiftool. If you dont have exiftool, you should look at the file exifdata and figure it out. This table is an approximation of what is used on most cameras: Name Temperature in Kelvin Sunny 5300 Cloud 6000 Shade 7200 Tungsten light 3000 Fluorecent 4000 infile is the name of the jpeg file of your photograph. if you know the color temperature that you should have used when you took your photograph, that is what you put as value for outkelvin. You have to know the color of the light that was there. outfile is the name of the jpeg file that will be created. If you want to save to ppm instead of jpeg append a .ppm extention to the filename, eg name it outfile.ppm instead of outfile.jpg Normally the ulitily will simply scale red and blue values, and clip anything out of limits. That means that either red or blue values may clip, creating blown colors instead of blown whites. If you want to clip/expand all color channels, specify an extra parameter clipscale. You can use any name, clipscale is only a suggestion, and this behavior will be activated by the presence of a 5th parameter alone. This will probably output a brighter image with clipped highlights (unless the original was underexposed enough to keep information of all three channels). That means, of course, that more information will be discarded