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Comment by hatsunearu | Hacker News Reader

Printing middle grey with an uncalibrated printer is uh... kinda meaningless.

https://smile.amazon.com/WhiBal-White-Balance-Pocket-Card/dp...

I've been using this for my photo adventures; I try to keep it in my wallet at all times (I worry about it getting discolored by rubbing against other cards though) and whenever I notice that the white balance is gonna get fucky (esp when there are multiple light sources) I whip that out and take a picture of it in the same scene.

edit: Also people love to use grey cards for getting exposure right but it's complete bunk science; if you're using the raw workflow (if you're fine tuning white balance you almost definitely are) you should shoot as bright as practically possible and not too bright to prevent clipping and adjust exposure as you see fit in editing.

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Unless you are doing extreme precision professional work--likely an extremely small subset of the people reading this, if any--a calibration target from a black and white laser printer or a photo printer is fine and will give great results.

Some photographers seem to worship color correction in a weird way. Other error factors, like reflected light hitting your calibration target, are likely to supercede any minor color imprecision from those kinds of printers.

Wouldn't practically all printers do middle grey with only black ink/toner/whatever, thus having very little chance of having any color cast? Considering how color temp adjustment is not very exact thing to start with, I feel that generic printout should be good enough for most uses. And for color critical work, you'll want a full color swatch (eg colorchecker) anyways instead of just middle grey.

I don't know the impact of this, but:

- there is no such thing as perfectly black ink

- color printers will mix color ink into greyscale printouts

A "fun" workaround would be to print a very high resolution black-and-white checkerboard. Printers generally have plenty of resolution to make that appear as gray even to the naked eye. Of course managing to print something like that without something in the pipeline trying to anti-alias stuff and introduce gray back is left as an exercise to the reader.

Thanks for posting the link, because I was about to ask. It seems like printing out the reference on a home printer would make the accuracy dependent on whether or not your printer was well calibrated (and then you're back to the same problem about color accuracy.)

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