On May 3, 2013, at 3:46 AM, Roger Breton <graxx@videotron.ca> wrote:
Everyone should have a ColorChecker chart on its shelves
The ColorChecker really is a wonderful tool. It's the ultimate white balance and exposure tool, as well -- though the ColorChecker Passport is even better. Develop the raw file with linear gamma and UNIWB; create a matrix profile from the result; and do a reverse lookup of D50 white. The result will tell you the channel multipliers you need to normalize white balance and exposure both. (Of course, you can do this with any chart, but the ColorChecker, especially the Passport, is so handy and ubiquitous.) Another really useful (though, I'm sure, unintended) feature of the ColorChecker is that your local paint store can match the paints for you (though you might need to go to a newer store with newer formulations with a sufficient gamut). The results you get will be spectral matches, within the historically-observed variation for the charts. If the store will sell you pint-sized samples, for about as much as you might spend on a new ColorChecker you can get a lifetime supply of paint to make your own in any size you might want. In the next week or so, I'll be making some for macrophotography, including one just 4mm x 6mm.... Cheers, b&