Composite Overlay Mask

[Marpel]

In Composite, if I use an Overlay Image, I can, of course, use an Overlay Mask.

However, if I use a solid color, chosen from the "Select Solid Color" picker, I can't use an Overlay Mask for that Overlay "image", even though the Overlay Mask has been pre-generated (clicking the mask box does not present a list of all available masks).

Can I presume then, the only way to use an Overlay Mask with a solid color as an overlay, is to generate a New solid color image first and then use that image?

Marv

[jsachs]

If you use a solid overlay color, the mask on the base image serves to control where the solid color is placed.

[Marpel]

Yes, I was trying to use both masks.

I had an image which had grid lines running across it and was using the grid lines to generate a mask (via Flood Fill), but I wished to restrict that mask to a smaller area of the image. I had already generated a (fairly complex) mask for that small area, for another task and was hoping I could re-use it for this purpose. I have often done this in conventional compositing with two images and just figured it would be easier to do it this way, rather than fiddling with the first mask. No worries, though.

Marv

[jsachs]

There are several ways to combine masks that you can use to solve this problem.

Most straightforward method:

Use the Save mask as image file command in the Mask dialog box to save each mask as a black and white image. Combine the two masks using Blend (or Composite) with the Darken operation. This creates a third image that is light only where both masks are light. Then you can use this third mask with your Composite as the base image mask.

More efficient method:

Let's call the two masks Grid and Small. Small is a mask that already exists either as a black and white image or as a mask for some other transformation. Grid is the mask you create using flood fill within a grid. In the composite base image overlay amount control, select Small as your starting mask by selecting it from the drop down menu when you click the white Amount box. Then select Save current mask from the Mask settings menu. Next create Grid as follows: first make the mask solid black by clicking the black button with the white arrow inside at the top of the Mask dialog box. Next use flood fill to create the flood fill mask (Grid) and finalize it. The last step is to combine Small (the saved mask) and Grid (the current mask) so that the final mask is light only where they overlap. So, change the Mask mode from Add (the default) to Overlap (the 3rd option). Finally, select Combine saved mask from the Mask settings menu. This combines Small and Grid in Overlap mode, giving you the final mask you want.

A third way:

Instead of making the Overlay a solid color, use File/New to create an image of all one color having the same dimensions as the base image and then select that image as the Overlay Image. Then you can use the 2-mask technique.

[Marpel]

Thanks.