Photoshop question

July 13, 2006 12:00 PM

Simple photoshop question... How do I replace all pixels of one color with a different color? (in photoshop 7.0).
posted by dial-tone to Computers & Internet (9 answers total)

tutorial here:
posted by empath at 12:05 PM on July 13, 2006 [1 favorite]

If it's pure single pixels you want to replace, and not a range of pixels in similar varying hues or values, then using the magic wand tool, select one pixel, making sure that "contiguous" and "anti-aliaed" are both OFF in the tool's options.

Then EDIT -> FILL with your colour of choice.
posted by Robot Johnny at 12:12 PM on July 13, 2006

Oh, and "tolerance" should be set to zero.
posted by Robot Johnny at 12:15 PM on July 13, 2006

Response by poster: What I'm trying to do is change the all white background in images (so all the pixels should have the same value) to a different color. The paint bucket does work to some degree, but it's somewhat tedious to have to fill every little section.
posted by dial-tone at 12:25 PM on July 13, 2006

Best answer: I can't think back to version 7 of Photoshop, but at least in later versions the paint bucket has a "contiguous" option as well, which, when turned off, makes the tool affect all like pixels whether they are touching (contiguous) or not.
posted by Robot Johnny at 12:34 PM on July 13, 2006

In such a situation, I usually make the white background transparent so that I can use any coloured background I want in the future.

First, I use the various colour channels to create a layer mask that'll allow me to delete the white background. I pick the colour channel with the best contrast between the background and object. I duplicate that channel and tweak the its levels until I get the best line possible. Then I colour in the object until I get a black and white image with no shades of grey in the middle. Then I use this layer as a selection to delete the white background in the original layer.

That's really the gyst of what I would do... I'm not sure if this makes sense to you or not...
posted by freakystyley at 12:50 PM on July 13, 2006

Menu: Select/Color Range
-Select the white background with the eyedropper, adjust the fuzziness to suit.
- If the selection looks OK, just use it as is.
- if the selection contains unwanted areas, go to Menu: Selection/Save Selection and save it to an alpha channel. The go to the alpha channel and paint the unwanted areas black.
- Then to apply the alpha channel as a selection go to Menu: Selection/Load Selection.
posted by doctor_negative at 1:01 PM on July 13, 2006

Choose the area with the magic wand tool. Fill. You'll have to do it a couple of times if there are non-contiguous background bits, but it keeps you from coloring the bits you don't want.

Or you can just do the magic wand then the background eraser, if you're looking for something that will be put on different things with different backgrounds. This is PS6, but I can't imagine that something this basic got cut out.

Good luck.
posted by Meep! Eek! at 1:31 PM on July 13, 2006

You can also do with image > adjust > selective color, and then choose white from the drop-down menu. You can then adjust away, but it will do all the white, not just the background.
posted by livinginmonrovia at 1:30 AM on July 16, 2006