Digital Light & Color

I have two images which are different dimensions, of which I wish to composite part of one into the other image. In Composite I generated a mask for the objects in the Overlay mask box.

Because the mask was not completely opaque, the objects did not show as clear as I wanted (although I was not looking for 100%).

In the past, rather than play around with the mask, I would merely repeat the composite operation, using the same mask to build up the density, as many times as necessary until the object was at the correct clarity.

I just tried to do this same thing but was unable to use the same mask a second time. In the Overlay mask box, the only choice I am given is "new mask" and in the Base image mask box, I am given the mask as an option (of course because the mask is not the correct dimensions, when I click on it, I get a size warning and the mask can't be used).

My question is, why can't I use the same mask I first generated, as a mask for the Overlay image in subsequent composites, while it is recognized, but not usable, in the Base image mask box? It seems the only way to use the same mask is to save it as an image file first.

Marv

First, it is probably easier to play with the mask by editing it and applying a shaping curve to the existing mask using the Mask Brightness Curve Tool (as opposed to the Mask Curve tool) as you can use this the lighten or darken the mask, making it more or less transparent.

You're right though, the existing Overlay mask does not show up -- I just fixed this in the latest (8.0.71) release.

Have been trying to understand your suggestion of using the Mask Brightness Tool (presume it is the last box in the row) to revise a current mask. Did the following steps with unexpected results. Perhaps you can provide clarification.

1. Made a gradated mask that is pure white at one end, pure black at the other end and a gentle gradation from one end to the other.
2. Composited an image onto itself, using Filter to better see the results. As expected, the resultant image was fully filtered at the white end of the mask and receded towards the dark end of the mask. Green mask overlay corresponds.
3. Using the Mask Brightness Curve tool, put points - 1. top left corner, 2. top edge, 2/10ths towards the highlight end, 3. bottom edge, 2/10ths away from highlight end, 4. bottom right corner. Expected "Apply" would reduce initial mask's effect to just the darker ends of that mask, but it actually reversed the Filter effect to the opposite end of the image and the green mask overlay also reversed itself. In other words, the filter was taking effect in the dark end of the initial mask.
4. Moved point 3 over two spaces towards the dark end. Green mask overlay flipped back to the opposite side but with less of a transition and the Filter effect on the image was returned to what corresponds to the white end of the initial mask.

I don't understand why the described Mask Curve(s) in steps 3 and 4 would allow the/any effect in the white part of the mask.

Marv

First, think of the mask as a black and white image, as though you saved it as an image.

Then think of the Mask Brightness Curve tool as applying the Brightness Curve transformation to the mask image.

A curve that starts in the upper left and goes to the lower right inverts the mask, which is not what you were trying to do.

To make the mask brighter (i.e. to make it apply more strongly), start with one point the the lower left, one in the upper right, and add a point in the middle and drag it upwards. This leaves black as black and white as white but lightens intermediate mask levels.

To make the mask darker (i.e. to weaken the effect), drag the center point downwards instead.

Another alternative to using the Mask Brightness Curve tool is to re-open the mask dialog box, click Undo once to undo the Apply of the gradient, and then edit the color line by double clicking on the starting or ending points and changing their gray levels. Or by adding intermediate points by shift-clicking on the color line and then adjusting their locations and gray levels. Then click Apply to redo the gradient with the new settings.

Thanks for the reply. And I think I get it now.

Marv