Hi,

I have been using a template (for a storyboard) and I am now on the 3rd page. On previous pages, each 'screen' square has a layer mask, meaning that when I placed any picture under that layer's group, it was only visible within the 'screen'. However, for some reason, that has stopped working and I can't seem to contain the pictures within the box unless I cut them to size... which has not been necessary.

The layer group still has a 'clip mask' on it - and I can see the white square, representing each position on the board, but it's just not masking - and is driving my nuts!

I've used Photoshop in the past - though masks are fairly new to me... as is Gimp. I've tried reading other posts and tutorials - but can't seem to get this to work.

PLEASE can someone help?

Ta!

If there is amsk on the groupo, it applies to layer in the group. If you want to contain pictures, you have toi put them in the group (possibly at the bottom) and not under the group (which is outside the group, so out of reach of the mask)

I'm sorry, Script Coder, I don't quite understand what you mean... I can see that the ones that are working, have a layer mask on the 'square group' and the clip group' - but the ones that don't only have it on the 'clip group'. I am guessing this is why... but I can't seem to match the settings for the masks that work... (screenshots attached)

This works:


This doesn't:

The mask on the Clip group layer only only acts on that layer (is this an imported PSD?). The extent of the group is limited by a mask on the group itself like in group #9.

PS. Name is "Ofnuts", "Script coder" is an attribute

Sorry Ofnuts!

Well that makes sense - I just don't know why I couldn't for the life of me create on on the group... well did create one - but I couldn't seem to get it to respond to the 'screen' only.... Hey ho - those that worked saved me time - those that didn't were a pain in the arse. Job done tho!

Thanks for your help - will have another go at trying the theory out another time!

Cheers.

I'm having some problems with the Layer Mask behaving inconsistently in GiMP 2.10.24 on Windows 10. Somehow, the alpha channel appears to be interfering with the Layer Mask.

What I want to do seems fairly straightforward if I understand the Layer Mask function.

I've created a simple "transporter sparkle in Poser, and did a render of two figures in the transporter chamber with an alpha mask. And, I did a render of the empty transporter chamber. Eventually, I hope to do an actual animation of it, preferably via an automated script. But script-writing is another topic entirely.

As I currently understand the process, I put the empty chamber on the bottom-most layer. The transporter sparkle goes in the next layer And the figures with their alpha channel go on top. Create a layer mask from the alpha channel (NOT using the transfer alpha mask function) and invert the alpha mask to give me two black figures on a white background in the layer mask.

As I understand it, what I SHOULD get is an image of the transporter sparkle as seen through the two black figures working like a pair of cookie cutters. What I get instead is a simple image of the transporter sparkle, as if there was no layer at all, or as if the mask was entirely black. If I return the layer mask to its original alpha channel appearance of two white figures on a black background, I get my two characters, with a background of the transporter sparkle image. That is, I believe, to be expected: the white silhouettes block the image from below, allowing the rendered characters to be seen, while the black background lets the underlying image to come through.

It's as if the original alpha channel and the layer mask cancel each other out. I CAN get the desired image of humanoid cutouts of the transporter sparkle ONLY if I either delete the alpha channel, or if I use the "transfer alpha channel to mask" function. Either way,. when I merge down, I'm left with an opaque image with no alpha channel, so I can't then merge the layers and get my transported figures into the transporter chamber.

What is worst of all, despite the problems of the alpha channel and the layer mask destructively interacting with each other, I actually DID it once! I even managed to get the figures semi-transparent with the sparkles overlaid, so that you could see the transporter chamber through the figures, with the particles on top of them.

But I didn't take notes, so I have no idea of how I worked around the odd problems with the layer mask. In fact, I didn't even notice any problems with the layer mask until I tried to do it a second time with different transparency settings. I guess I have a few more experiments to do, this time taking careful notes so I can reproduce it. With the alpha channel and the layer mask not playing nicely together, it's tied my brain up in knots. Or, at age 67, I'm experiencing early symptoms of senility, a truly frightening prospect. How can you tell your mind is malfunctioning if your mind is the only tool you've got to analyze with?

Thinks are clearer with a screenshot of your Layers list...

If you initialize by transferring the alpha, the layers original alpha is made fully opaque, so the final result depends strictly on the mask. If you use other options, the final alpha is a combination of the layers original alpha and the mask (more or less applying the mask in "Darken only" mode to the original alpha).

If you want a layer to be limited by the contents of another, the classic solution is to to "Alpha to selection" on the layer with the shape, and on the other layer, add a layer mask, and initialize to selection.

In Gimp 2.10, a better solution is to put the two layers in a group, and have the "Composite Mode" of the top layer set to "Clip to backdrop":