Color to alpha greyed out

The Color to Alpha command makes transparent all pixels of the active layer that have actually a selected color. It will certainly attempt to preserve anti-aliasing information by using a partially intelligent regimen that replaces weak shade indevelopment with weak alpha information. In this way, locations that contain an facet of the schosen shade will keep a blended appearance through their neighboring pixels.




You watching: Color to alpha greyed out

Note
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This command is normally grayed out : you have to include an alpha channel to usage the command.


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Presets, Preview, Split watch

These options are common to GEGL-based filters. Please describe Section 2, “Typical Features”.

Color

Clicking on the shade swatch provides a shade selection dialog wright here you deserve to pick a color. You deserve to additionally choose a color making use of the eye dropper on the appropriate.

“Color to alpha” comes through a GEGL option dialog under Toolbox. When the Sample average alternative is unchecked, color picker picks only one pixel shade. When the choice is checked, mouse guideline goes via a square limiting a pixel sample that determines a combined sample “color”. You deserve to settle square size straight in message box, or utilizing arrow heads, or Up and also Down keyboard secrets.

Right clicking the shade swatch will display screen a food selection wbelow you deserve to select Foreground or Background colors, White or Black.

Transparency and Opacity thresholds


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Transparency: the limit listed below which colors become transparent.

Opacity: the limit over which colors become opaque.


Color to Alpha modifies the transparency (and color) of the pixels based on their distance from the schosen background shade (the "Color" option) -- the closer they are to the background color, the even more transparent they become, with the background shade coming to be completely transparent.

The transparency and opacity thresholds control exactly how close colors have to be to the background color before they come to be totally transparent, and just how much they should be from the background shade prior to they reprimary totally opaque, respectively. With the default worths of 0 and 1, only the background shade becomes completely transparent, and just the colors farthest away from the background shade remain completely opaque.

For instance, while the default worths work-related well for removing a white background from a babsence object, if the object is gray instead it will certainly end up being semi-transparent , because gray is midmethod between white and also black. Lowering the opacity thresorganize to 0.5 fixes that, by maintaining all pixels that are gray or darker (all pixels whose distance from white is 0.5 or even more, on a <0,1> scale) totally opaque .

The transparency thresorganize functions similarly: raising it reasons even more colors in the area of the background shade to become completely transparent. This is mostly beneficial with noisy imeras, in which the background is not totally solid. However before, unprefer in various other situations, as soon as the transparency threshost is over 0, rewriting the result against the background color no longer reproduces the specific exact same image.

At the threat of being a little technical, this can be visualized by thinking of the RGB cube. The background color is a suggest within the cube, and also the transparency and also opacity thresholds are 2 sub-cubes focused about the background shade. Everything inside the transparency-threshost cube becomes completely transparent, everything external the opacity-threshost cube continues to be completely opaque, and also every little thing in between progressively transitions from transparent to opaque. In image you have the right to see the Red-Environment-friendly challenge of the RGB cube. (1) is the background color (Red=0.5, Green=0.5, Blue=0.0), (2) is the transparency thresorganize (collection to 0.1), and (3) is the opacity thresorganize (collection to 0.4).