Remove white part of every color to make lighter parts more transparent

My problem is so general, and there are version-dependent plug-ins for the problem not working with my version. I also found workarounds that are not the correct solutions.

I would to convert my image’s white to transparency, i.e. decompose gray to black and transparent. It would be correct if I could use the saturation value of the pixel from the HSB (de)composition, make every pixel’s saturation to 100% from it’s original s(x,y) value, and add a 100% – s(x,y) transparency to the pixel.

As the mentioned and many other workaround suggest, using the image itself as an alpha channel is not a solution. E.g. if the pixel is 20% white and 80% gray, and you apply a 20% transparency, then the pixel will look look like 80% – 0.8*0.2 = 56% black instead of 80%.

Another stackexchange question on turning white to transparent is similar to my problem but as I understand, it does not cover my problem. In case if I’m wrong I’d appriciate if someone enlight me how to apply that for my scenario.


I know you asked how to do this in Photoshop, but this may be one of the few cases (now that Photoshop has content-aware fill too) where GIMP does the job better. So my suggested solution would be:

  1. Download and install GIMP. (Scroll down for the Windows installer.)

  2. Open your image in GIMP.

  3. Use the Color to Alpha tool to convert white to transparent (masking and tweaking as needed, if you want to retain some non-transparent white in the result).

  4. Save the resulting image and reopen it in Photoshop.

Note: GIMP can import and export Photoshop .psd files, but some information may be lost during the back-and-forth conversion. It may be safer to only edit your PSD files in Photoshop, and to use the PNG format for transferring images between Photoshop and GIMP instead.

Source : Link , Question Author : DanielTuzes , Answer Author : Community

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