If I understand your question, I would select the layer containing the transparency you want by Cmd-clicking the layer thumbnail. The selection is now simply based on the transparency, not the pixel colors. This selection can be saved as an alpha channel or used as a layer mask on another layer.
My objective is to make a gradient map of the photograph in opacity, left to right, 100% to 50%. Not sure I understand your reply, Ray. When I read about gradient map tool, it doesn’t refer to anything but working with colors.
When I read about gradient map tool, it doesn’t refer to anything but working with colors.
That’s what a gradient map is about…
Unless you mean a gradient mask? (Have the photo become gradually transparent from letf to right) You do that with a layer mask and the gradient tool.
I think he means he wants to map the opacity of the image… so that, let’s say, the black end of the gradient would represent full opacity, the white end would represent full transparency.
Correct, Doug. Thank you CN. Got it working now.
Really. How do you do it? How to you map grayscale tones to opacity?
I think he means he wants to map the opacity of the image…
Ok, but where does the left to right come in?
Mapping grayscale tones to opacity:
Place the image on a layer, make a layer mask, copy the grayscale image, paste it in the mask.
Or, use a fill layer, and paste the image in the mask.
The results are different and one may be preferable over the other depending on what you’re doing exactly.
