Simple Alpha Use as a Selection

First, I'm baaaaaack!  :+)))  (Many thanks to John for getting me up to speed with 4.04, among all the other awesome things John does!)

Oh, man, I forgot how much I love this software!

And it's absolutely amazing how many things I've forgotten ... chalk it up to an aging brain I guess.  :+)

So here is my very simple question: I have a source file, which is RGB+A. What I want to do is to use my source's alpha channel as a selection (I think?), which hopefully will allow me to paint into the selection areas only. (And if not, I can invert the selection, no?)

So far, I've tried everything I can think of, and have failed to accomplish it.

Do I need to use a second layer? So far, given my understanding of what a selection is, I'm only using one layer ...

Please, will someone give me kindergarten-level step-by-step instructions on how to use a source's alpha to paint only into the brighter areas of the alpha channel, as if it were a grayscale-based selection?

Thanks for any help!  :+)

Michael

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Replies

  • If you run the Canvas : Selection : Set to : Source Alpha menu command, that will set the selection buffer to the source images alpha channel.

    • Thank you, John. That really helped. Mainly, I had failed to turn on Mask!  :+)

      Now I have two questions:

      -- Is there a way to apply paint via an alpha channel/selection/mask with full grayscale values, where the darker values proportionally block the paint from hitting the canvas?

      -- Is there any way to make the mask invisible, but still operative? I find I'm "guessing" on the outcome, because the masked areas are not fully visible, for context. (Yes, I can stop painting and turn the mask off and on, like temporarily removing a frisket, but that kind of interrupts my flow.)

      Thanks!
      Michael

      Lighthouse-003b.jpg

    • You can work with the paint synthesizer controls to do your masking (as opposed to using the mask checkbox). if you do it that way, the mask will always be invisible.

      ...

      I talked about ways to restrict path start, path end, and path application based on the selection in a previous reply here.

      ...

      If you want to mask the individual paint nibs, goto the Paint Fill Apply control panel, and set the Nib Masking parameter to the If Region option. The the individual paint nibs will be masked by the selection.

      ...

      There is a Current Selection Region option in the Blend Mod parameter in this control panel. This option will modulate the paint nib blend to the canvas based on the selection value at the nib center. Blend Mod will appear if you are using any Composite option except Replace.

  • Just to clarify, here is what I have tried so far, thinking it was a logical path to take:

    After using Paint Synthesizer Classic to cover the source image with painterly color,

    1. Canvas: Alpha: Set To: Source Alpha (I made sure the alpha was in the source file)

    2. Canvas: Selection: Set to: Source Alpha

    3. Source Area: Choose "Color" instead of "Image", then choose a "complementary" color to the source image's general color ... (basically just so I can see the new paint)

    4. Choose a paint preset and Run Loop Action, which "should" paint only in the selected areas (or so I thought)

    Unfortunately, paint goes "everywhere," instead into only the selected areas.

    Why? Or maybe I should be asking, "why not?"  :+)

    Again, thanks for any clarifying help!  :+)

    Michael

    • If you turn on the Mask checkbox in the main operation toolbar, then your paint will be masked (based on the contents of the selection buffer).

      ...

      Here's a tip on how to select and mask the canvas. Also, read the section called Paint Masking Option, because you can use the selection buffer to mask painting in different ways.

      ...

      You can also use the selection buffer, or the source alpha channel, to constrain painting in the paint synthesizer as a part of a paint preset. So you could constrain path starts so that they only happen in the selected area of the canvas, or the part of the source image where the source alpha is full on. Look at the Inhibitor parameter options in the Path Start control panel.

      ..

      There are similar parameter options in the Path End control panel, to inhibit path generation when a generated path moves outside of the current selected area, or the current source alpha full on mask.

      ...

      You can also inhibit individual paint nibs, based on the parameters in the Path Application control panel. Look at the options for the Probability parameter there. Source alpha masking is missing there, so we'll add that for the future as an additional option.

      ...

      The nice thing about working with path start and path end options to inhibit painting is that you can end up with a much more natural painted look than just hard masking painting using the Mask checkbox in the operation toolbar.

      ...

      Note that none of this discussion mentioned anything about alpha channels in layers, since you don't need to use them or turn on alpha view to do any of this stuff.

      If you do want to learn about working with alpha channels in layers, heres a tip on that.

      But for most operations in Studio Artist you can just leave alpha view turned off. So it's a very different philosophy than photoshop, where alpha view is always on.

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