What does ‘alpha’ mean in design software?

I’ve never done any graphic art or design. So I have a super basic question. I’m learning to use Krita. I keep seeing the word “Alpha”, what does this mean/refer to?

When I choose to create a new document in Krita, a dialog box pops up so that you can select different options for the document. The options for color model all have “/alpha” next to them. So the options look like this:

  • RGB/alpha
  • CMYK/alpha
  • Grayscale/alpha
  • XYZ/alpha
  • etc.

Each option has that after it.

Also I just learned what an alpha channel is. So… I guess I’ve really only seen it twice, but still, I want to know that means. Are there other “alpha” things too that I haven’t learned about yet?

Answer

‘Alpha’ is the opacity channel. Each layer can have such a channel, governing how transparent or opaque every pixel on the layer is.

Such a channel is essentially a greyscale image of exactly the same dimensions as the layer. Every pixel on the alpha channel corresponds to the same pixel on the layer. The colour of a pixel on the alpha channels affects the opacity of the corresponding pixel on the layer.

Usually, 100% black means 100% transparent (and thus invisible) and 100% white means completely opaque (or 0% transparent). Any percentage of grey is an intermediate opacity.

This way, an alpha channel allows you to control each pixel’s opacity separately.

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Source : Link , Question Author : Person , Answer Author : Vincent

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