I have this image:
and I want to change it so it looks gray instead of black. My problem is that it has some anti-aliasing, so there are some half-transparent and/or gray pixels on some borders. If I select everything that's black and change it to gray, those pixels end up being much darker than what they should be. And if I was trying to switch to another color, like red, it wouldn't work at all.
This is something I find myself needing quite often, so I'd like to learn how to do it. What's the conceptual way of doing it? and/or how do I do it with Pixelmator?
I did this in Photoshop, but conceptually it should be very similar:
Just adjust the brightness. Gray is just a whiter black, and so lightening everything proportionally should give you the results you want.
I did it with the Brightness/Contrast dialog, but you could do it with Levels too. I'd imagine Pixelmator has these features. I checked out the help pages, and this looks like your help file for brightness and contrast, and this is levels.
If you want to change color, I'd use the Hue/Saturation dialog with the "Colorize" box checked in Photoshop. Here are what I believe to be equivalent instructions for Pixelmator.