Simple colour replacement problem

[prof]

A small and perhaps obvious but very frustrating issue.
Here is a PSP file and I want to change the black filmstrip edge from black to white, using low tolerance. Normal procedure does not work.
For me it either does nothing or changes a small part (right click on black), or the blue changes to white (left click) or to black (right click on blue).
It is as if the black elements are hidden - yet it is a single layer and those pixels show up as 0,0,0.
I am not sure of the source of the graphic but it was a png.
Please advise.

[LeviFiction]

Are you using the color replacer tool or the color changer tool?

Color changer will change the color (hue and saturation) and maintain the lightness values to preserve texturing. It's not really made for flat colors, though it can be used that way. In the case of changing from black to white, well that's a lightness attribute not a color one.

The Color Replacer brush on the other hand will replace the background color with the foreground color. So to make it work you need to change the foreground color to white, and the background color to black and it should work nicely. But there is no tolerance setting so you have to match colors exactly with this. This tool is made more for flat colors.

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With this image, however, there are two ways you can easily make the change

1) Use the regular fill tool, you'll need a higher tolerance to get all of the darker but not quite black pixels. 139 worked for me.

or

2) You can duplicate the layer, turn the top layer to a negative version (Image -> Negative Image) and change the blend mode of that layer to Luminance. then merge down to flatten.