How can I fix screenshots with subpixel rendering?

Question

When taking a screenshot of some text with subpixel rendering, the result is very ugly, especially in print. Obviously, the best way to avoid this is to deactivate that option before taking the screenshot but let's say we already have a screenshot where this didn't happen and that's difficult to replicate. What is the best way to mitigate the colour fringe artefacts?

Here's a small part of a screenshot as an example:

The text on the white background is the easy part. Here's a partly desaturated picture:

Far from perfect but good enough for me. Now with the blue button, the desaturation obviously wouldn't work:

The best I could come up with so far is to desaturate locally and then do a "color" overlay with a layer containing only the blue button with the text edited out:

Unfortunately, the result is quite awful:

The "Hue" overlay mode in gimp doesn't do anything useful at all in this case which I don't quite understand.

So I'm quite lost since I have the feeling that this should be solvable but I don't know what to try anymore. If I need Photoshop for this then so be it but I'd prefer an open source solution if at all possible.

One last thing for the record: I found that upscaling the picture by a factor of 2 with some good interpolation (I used Lanczos) vastly improves the look of the clumsy manipulation in print.

Answer 1

As you'll have noticed, interpolation makes things blurry... especially in print.

For print, you are best advised to push up the DPI by taking (eg) a 72 DPI screenshot and scaling things up by pushing (resizing) the DPI up to 288 with "Nearest Neighbor (preserve hard edges)".

And if you've got time, you can get rid of most of the subpixel pixels by color-replacing their colors to match their origin a bit more (which kills off the color weirdness around the fonts a bit better).

Note that - whenever you're going to scale the screenshot - you'll get bad results in print with your screenshot, unless you scale the DPI in according steps (72, 144, 216, 288, etc.) and crop what doesn't fit.

As you know - there's a big difference between what you see on your screen and what things look like when they get printed. To give exactly fitting tips on your issue, we would need to know things like size and DPI of your screenshot, and the target DPI or LPI - depending on the medium you're printing.