A small optimization

| Comments (5) | Software
A few weeks ago I helped a friend calibrate the color on his photo printer. The basic idea here is that you print out a test sheet containing patches of various colors. You then scan each patch with a handheld sensor. The color correction software compares the intended color to the actual printed color and generates a correction profile for the printer.

The process is simple but tedious. The basic test sheet contains a hundred or so patches and you need to scan each one individually. Something like this:

Once you've printed the test sheet, you position the sensor over each patch, press the botton on the top of the sensor, wait for it to scan, and then move onto the next patch. Aside from being boring, this procedure is kind of error prone. It's pretty easy to forget to press the button and get off by one or two targets. And since the whole point of the exercise is to deal with the printed colors being wrong, the software doesn't freak out when the colors don't match. Luckily, it does tell you which patches it thinks you've scanned, so by the time you get to the end of the row, you do figure out it but then you probably have to rescan it.

This isn't awful, but there's an easy hack that would make it better. The reason that the software can't detect that you've made a mistake is that the the test sheet is basically a color ramp, so color patch n and color patch n+1 are quite similar. Simply re-arranging the colors so that contiguous colors are quite different would make it possible to automatically detect mistakes (unless the printer is incredibly screwed up).


Or just get a strip-reading spectrophotometer from a company like Xrite and it's ten times easier, since you just drag it across the color bars. Doing it one patch at a time is kind of last-century.

Hmm, doesn't the profile of the scanner screw this up a bit?

Easiest thing to do is to let Cathy do the grunt work. http://www.cathysprofiles.com/

She's inexpenstive, prompt, and good.

Eric -

Do you notice any difference after calibration? Was this for photo quality printing?


Yeah. It looked worse!

This was at a friend's house and he says that there was some other correction filtering he had to remove but it looks fine now. Yeah, it was for photo printing.

Leave a comment