Understanding the Mask for Varicolor Raster Symbols

I understand the steps from both the Tome and Help on how to create a varicolor raster symbol, but I don't understand how the mask image works.

Specifically;
- what parts of the mask (_02.png) get the varicolor?
- is it required that the mask image be grey scale? What happens if its not?
- Do the darker parts of the mask (assuming grey scale) get brighter or darker (saturated?) of the varicolor color?
- Vector varicolor have the ability to do shaded varicolors, can you do something similar with raster varicolors?

Thanks in advance :)

Comments

  • MonsenMonsen Administrator 🖼️ 46 images Cartographer
    - All of it that isn't transparent
    - No. It is the mask that is important, and that is just a bunch of transparency values
    - Yes. The alpha value of the mask is applied to the color, so the darkest parts (no transparency) gets the "full" color, while the rest will be using a varying degree of transparency, leading to a less-saturated color.
    - Not quite the same way, as the vector varicolor is based on the palette, you can do some weird stuff, but the intended effect is the same. As you vary the amount of the color (through the mask) that is blended with the image, you get varying shades of that color.
  • Thank you!
    Posted By: Monsen
    - Not quite the same way, as the vector varicolor is based on the palette, you can do some weird stuff, but the intended effect is the same. As you vary the amount of the color (through the mask) that is blended with the image, you get varying shades of that color.
    So if you do not use greyscale, then you can blend the mask color with the varicolor color?So you could make part of the mask red with something like 50, 30 & 10% transparency and get a red tinted variation of the selected varicolor? I assume this means you could also do things like parts of the mask being red, blue, & green with transparency to get other effects as well?

    Interesting, not sure I have such a need, but now that I know, I might think of something!
  • MonsenMonsen Administrator 🖼️ 46 images Cartographer
    edited February 2018
    Posted By: LordEntrailsSo if you do not use greyscale, then you can blend the mask color with the varicolor color?
    No. The color values in the mask image isn't used at all, only the alpha channel (transparency values). To blend, you need the symbol image to be in color, as the color in the symbol image will blend with the varicolor color, where the amount the varicolor color contributes is determined by the alpha value at that pixel. (Which is why the symbol can't have strong coloration, as this will overwhelm the varicolor)
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