snibgo

As you use IM v7, I suggest you use "magick", not "convert". You seem to create those tiff files with Gimp. Is that correct? If so, it might help if...

You have shown screenshots. I thought they were Gimp, but I was wrong, sorry. The first one says it is Adobe Photoshop. I don't use Photoshop. So, when you open...

IM can't see layer masks in tiff files. It can see only images, and ignores any mask data. If layer mask data is present, it is in private Adobe tags....

See the layers documentation at https://imagemagick.org/script/command-line-options.php#layers . This is fairly precise, and accurate as far as I know. "-layers mosaic" seems to do what you want.

Your command doesn't include "-layers coalesce", and doesn't need to. That operation is designed to complete frames that have been compressed by storing each frame as only the bounding rectangle...

From layertest.xcf, you want to make three PNG files, each 230x165 pixels, with no offsets. Width 230 comes from layer[2] where w=53 and offsetX = 177. Height=165 comes from layer[0]...

How did you make layertest.gif? I suspect you didn't make it with IM. The software that made that could read the "overall canvas" from the XCF. As you can see...

But it isn't doing that for the GIF. Your GIF already has the overall width and height as the canvas size for every image. Your XCF doesn't. Technically, IM could...

> The idea of a per-image canvas size is an ImageMagick thing; in both actual formats the canvas size is global, and correctly set to 256x192. It isn't _just_ an...

I note that coders/gif.c ReadGIFImage() has a variable called meta_image. meta_image->page.width and meta_image->page.height seems to be where the global canvas size is stored. It might be sensible to provide an...