Issues with color to alpha borking background color.

[kulharin]

I am experiencing an issue trying to add semi transparency to this spectre and full transparency to the grey background.   I select the entire image and choose color to alpha, I select grey as the color... If I set the threshold (too low I guess) and it seems make the background this dark blue/green color that is not transparent at all?  What am I doing wrong?

[rich2005]

Is that the only image you have ?

Do you have the symbol and the "spectre" as separate images ? If you have then post them.

[kulharin]

I do not, it is an in game screenshot from Skyrim. Intended for use with this mod. https://www.nexusmods.com/skyrimspeciale...ods/123521 ... So they need to be from in game during an active animation with the applicable effects. I use an in game review studio that allows me to spawn creatures inside a white, black, green or blue room, which becomes the background. I have been using the fuzzy select tool for some creatures, which can be a tedious pain depending on the creature. But the ones that are fully semi transparent I have issues with color to alpha.

[denzjos]

Not perfect but I tried this:
Copy the original layer and desaturate the layer(Colours / Desaturate / Mono mixer - play with the sliders)
Set the other original layer not visible
Copy the desaturated layer,optimise with: Colours / Brightness Contrast - use contrast  and remove white background with: Colours / Color to Alpha
Set the desaturated layer not visible
Copy the desaturated layer a few times to darken the object
Make a new layer with this layers : New from Visible and set the desaturated copied layers not visble
Select the dark object with the fuzzy select tool, and make a copy from the original layer
Select one of the copies and 'Add Layer Mask' / From selection
Copy this layer and invert the layer mask from this layer :    Colours / Invert
Play with the layer opacity
A small example from the original :

  spectre.7z (Size: 340.83 KB / Downloads: 3)

[rich2005]

Still not sure what is required Instead of fuzzy select maybe use color select to obtain a white BG (leave alpha off for the moment). Color select with draw mask enabled - click and drag to define a selection then Edit -> Cut then Select -> None.

Now apply color-to-alpha and you might have more success with the white BG.

Sometimes the eraser tool in anti-erase mode can restore parts of the image.

For tweaking transparency. The curves tool using the Alpha channel.

Some of that might / might not be useful. I can just get it into a 60 second animation https://i.imgur.com/0WrmryZ.mp4

Another possibility is the gmic_gimp_qt plugin which has an interactive-extract filter, but that is different story.