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+--- Thread: change a layer while keeping another (/Thread-change-a-layer-while-keeping-another)
change a layer while keeping another - Chris - 04-10-2021
I have a photo (of a big sunflower head) and a mathematical figure (many big red dots). The photo is somewhat distorted and needs transforming by trial and error, to have the dots fit on top of it. Making one layer transparant is no solution because fuzzy views won't do. Nothing I tried so far with GIMP allows to manually adapt the photo (Perspective, say) while the layer on top of it remains unchanged as if on a glass plate.
RE: change a layer while keeping another - rich2005 - 04-10-2021
Really depend how much transforming is required. If it is possible with one of the Gimp tools Unified Transform or maybe handle transform then make sure that composited preview is enabled. Then easier if the target pattern is on transparency but not essential.
[attachment=5850]
A quick demo of that: https://i.imgur.com/XNUnc3I.mp4
Otherwise if some sort of Grid distortion is required...well...Gimp does not have one (or rather the one it did have is broken)
Also, if there are not too many reference points they could be marked with guide lines.
RE: change a layer while keeping another - Chris - 04-10-2021
(04-10-2021, 04:08 PM)rich2005 Wrote: Really depend how much transforming is required. If it is possible with one of the Gimp tools Unified Transform or maybe handle transform then make sure that composited preview is enabled. Then easier if the target pattern is on transparency but not essential.
A quick demo of that: https://i.imgur.com/XNUnc3I.mp4
Otherwise if some sort of Grid distortion is required...well...Gimp does not have one (or rather the one it did have is broken)
Also, if there are not too many reference points they could be marked with guide lines.
I think Perspective alone would do. But my photo consists of some 1000 densely packed seeds, and I for my finetuning I really need two fully visible layers, not one that is partially gray. (I got a headache matching 2000 partially visible dots.)
(04-10-2021, 04:08 PM)rich2005 Wrote: Really depend how much transforming is required. If it is possible with one of the Gimp tools Unified Transform or maybe handle transform then make sure that composited preview is enabled. Then easier if the target pattern is on transparency but not essential.
A quick demo of that: https://i.imgur.com/XNUnc3I.mp4
Otherwise if some sort of Grid distortion is required...well...Gimp does not have one (or rather the one it did have is broken)
Also, if there are not too many reference points they could be marked with guide lines.
RE: change a layer while keeping another - rich2005 - 04-10-2021
Quote: think Perspective alone would do. But my photo consists of some 1000 densely packed seeds, and I for my finetuning I really need two fully visible layers, not one that is partially gray. (I got a headache matching 2000 partially visible dots.)
So that means the 'pattern layer' is not transparent? Can you apply a Colour-to-Alpha to remove the BG leaving the dots?
The composited preview is the setting you need.
RE: change a layer while keeping another - Chris - 04-10-2021
With Colour-to-Alpha I reduced the pattern layer to the dots, merged the layers (the perfect view I want), selected the dots by colour, inverted the selection, and hoped to transform that selection while keeping the dots as they were. Did not work!
RE: change a layer while keeping another - rich2005 - 04-10-2021
Quote:... I reduced the pattern layer to the dots, merged the layers ... did not work
Why did you merge the layers ? Keep the dots in their own layer on top, Use a transform tool on the picture layer with composited preview.
look at the animation again. https://i.imgur.com/XNUnc3I.mp4
RE: change a layer while keeping another - Chris - 04-10-2021
(04-10-2021, 05:38 PM)rich2005 Wrote:Quote:... I reduced the pattern layer to the dots, merged the layers ... did not work
Why did you merge the layers ? Keep the dots in their own layer on top, Use a transform tool on the picture layer with composited preview.
look at the animation again. https://i.imgur.com/XNUnc3I.mp4
I understand what you are saying. But your flower is partially greyed out, no? I want it fully visible (as clearly as in the post-transform view) while I'm transforming it. The red dots on a clear glass plate, so to say, not interfering in any way with the lower layer. Perhaps it's just not possible (though my trick with select-by-colour sounded like a good idea).
RE: change a layer while keeping another - rich2005 - 04-10-2021
Quote:I understand what you are saying. But your flower is partially greyed out, no? ..
Not if the target (dots layer) now has a transparent background.
Repeating myself. Keep the dots in their own layer on top, Use a transform tool on the picture layer with composited preview
This with the 2 layers and the unified transform tool for a change: https://i.imgur.com/vq5gKlE.mp4
RE: change a layer while keeping another - Chris - 04-11-2021
(04-10-2021, 06:37 PM)rich2005 Wrote:Quote:I understand what you are saying. But your flower is partially greyed out, no? ..
Not if the target (dots layer) now has a transparent background.
Repeating myself. Keep the dots in their own layer on top, Use a transform tool on the picture layer with composited preview
This with the 2 layers and the unified transform tool for a change: https://i.imgur.com/vq5gKlE.mp4
Great, that's it (after getting a newer version of GIMP). Thank you for your patience.