I include MS Windows screenshots in documents I create. I cannot always get the same color for the window frame, so I change that color in Photoshop. That works OK, but the dithering around the text in the window frame is wrong because it was based on the original color, and the pixels are not selected by the magic wand when I select the area to change the color. How do I adjust the dithering to the new color?
I'm going to guess that when you refer to 'dithering' you mean the transition pixels between text black and the color of window frame (image area) you are changing. You could try to adjust the feathering for the magic wand tool and see if that 'grabs' those pixels. You may also be dealing with such a low resolution image that getting a clean transition might not work without using some other technique - and in PS there are many.
open screenshot in Photoshop
Edit> Assign Profile: your default monitor profile
Edit> Convert to profile: sRGB
and Save As your copy
i would think doing that you should have an exact match in Photoshop?