This is kind of a PSA I guess.?
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When I teach workshops in digital negatives and DTP processes using QuadToneRIP, many people get heartburn at the notion of spending anywhere from $300 to $3000 for a used or new X-rite spectro. I found this little colorimeter sold by ColorMuse that connects to an app on your phone and gives remarkably accurate LAB values when compared to my X-Rite i1 Pro2. The second version of this little device is around $100.:
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The knock on it is that creating a data file that you can use in either the QuadToneRIP linearization or Richard's QuadToneProfiler apps is a little tedious.?
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The device itself is a little chunky, so you probably will want to print targets that have ?" or larger squares so you can hit the measurement exactly. I have a few of those in the downloads area of my website.
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I wrote a little javascript widget that can be found here:
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that lets you enter the measured values as you read them and then downloads a standardized 21-step text file that you can use in these programs. This is a more sophisticated version of an earlier table based entry form because there is no requirement that you have evenly spaced steps. It uses a cubic spline to resample whatever garbage you enter into a 21-step text file. You can graphically edit the L or A or B files if you want to manually smooth them before downloading the text file.
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This is only really relevant to someone who only occasionally needs to linearize a quad file. If you are a high volume measurer, you will probably want to get a more capable measuring device.
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Note that I am not a programmer of any great skill, but I think this is reasonably robust. Give it a try and send me any feedback if you find problems.
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