In Darktable 4.7 we now can use canvas enlargement and I used it to insert a white margin. To my surprise the margin partly turned blue which was easy to explained as graduated density was active. Deactivating graduated density solved the issue, as shifting canvas enlargement in the pixel pipeline above graduated density.
This triggered me to further examine the effects of color adaptions on the whiteness of the margin. I wasn’t surprised to see that any colors modification in the photo affects the margin color. So white isn’t always white, nor green isn’t always green. Using masks I predictably could isolate the effects on the margin colors.
So, in canvas enlargement the margins created are an intrinsic part of the photo: changes in a photo will affect the margin too, unless one masks. To my opinion this decreases the usability of the canvas enlargement module.
For a simple frame, there is already a module named “Framing” which is at the top of the pixel pipe. So colour modifications in the image will not affect the colours you set for your frame.
Otoh, if you enlarge the canvas to have more image pixels, IMO you’ll want those new pixels to follow colour changes you make to the image.
I am always glad to see work progressing on DT. I wonder what the intended use of this module is for? I use something similar in GIMP to combine pictures into a panel. Is this the idea with DT or are there other uses envisioned?
Terry, I don’t remember where I got this from. Might have been mentioned in the code.
Enlarge Canvas : As the name imply this module can be used to add
areas on the left, right, top or bottom of the image. The new area
can be assigned different color to help masking if necessary. The
new areas can the be filled with the Retouch module by copying
some other part of the image, using Liquify if the area is small
or the new module overlay.
I can’t see a way to increase the canvas by more than 100%. Often I like to show progress shots of my ship building by viewing a triptych, for example. It would be nice to be able to extend the canvas more than 100% in any direction.
I suppose you could add a banner to one side and add a sort of watermark in that space or some combination of added area’s… to come up with something like that…
If that’s the case, maybe what @arturoisilvia did was to expand 100 percent and add image no. 2. Then saving the composite and then expand 50 percent and add image no. 3?
Arturosilvia posted a triptych in the post I linked to above. This was presented as a response to my question whether we can use the new module to create diptychs and triptychs.
So if it’s true that one can expand only 100 percent, as you say, I’m wondering if he perhaps first doubled the canvas and added a second image, exported the composite image, and then opened the new file, expanded it so as to add the third image and frames?
If one can expand canvas to the double, and then scale down images applied to it, this may perhaps also be a way to achieve triptychs. You who have v. 4.7 could perhaps look into this.
While doing such things as diptychs and triptychs within darktable is nice, I have to wonder if it isn’t going a bit beyond whats needed, the more so as there are programs that allow this kind of operations already (Gimp, Krita, probably others). And with them, you have many more possibilities (e.g. with respect to framing etc.).
As this thread is about the “canvas enlargement” module, do you really want the expansion to be independent of the rest of the image? Or is that a sign you are abusing the module beyond its design limits? (In hte specific case of diptychs and tryptichs, you’re probably also pushing the overlay module beyond itslimits…)
Darktable is a program with a linear pixel pipe. As such, anything done within that pipe will be influenced by everything later in the pipe, unless you start using masks.
The program @Pieter_Zanen quoted is based on a node graph wich allows parallel paths. That’s a rather different implementation, with a different basic design behind it. While independent processing of two parts of an image is fairly natural for such a system, forcing that concept into darktable won’t be pretty, if it even is doable.
May be.
I’ve just wanted to know what the new modules can be used for, as creating diptychs/triptychs are the only thing I currently feel the need to access Gimp or any other image program outside dt for.
Thanks for the input to such clarification!
EDIT: Threr is already a sneaky method to make overlays by “abusing” the watermark module. As long as it works, there seems to have been those who have been happy to use it for e.g. changing skies
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