Filling cells with color from another source

You are probably familiar with what the Solid Fill checkbox does in noise nodes. When the same source image is fed to both the Noise and Background inputs then it produces something like this:


Now, I'd like to have a generalized way of doing this: the inputs are a grayscale and a color image. Each continuous area of the same gray value should get the color from the color image, from the location of the "center" of the gray cell (or the average color of the same area on the color image).

So the main problems are:
- Finding cells.
- Finding the center of each cell. Using that position as cell color somehow would be great.

Right now I have no idea how to begin so I'd appreciate any pointers.

Yeah, good points. Quantizing the grayscale values seems to be a good way to decrease the number of cells on the image (8-16 gray steps?). Then the coloring logic could only work on one particular shade at a time.

So the steps could be like:
- User selects "1" brightness index.
- Algo looks for grays of 1/8 brightness and collects contiguous areas.
- Colors those areas to the coordinates of their centers.
- User saves the image and processes it once again with "2". (The filter can tell unprocessed texels from processed ones based on the blue channel.)

If it's possible to flush the LUA interpreter manually between passes then maybe the passes could be done with the loop node.

Still seems to be too much work for what I need it for...

Right. If I were to make such a filter -- and I am not planning on doing so -- I would likely make it a multiple-filter affair, meaning make one filter that only creates the flat gray areas that you can then use with the Lookup Component in another filter. Waiting for the first step every time one changes a setting would be excruciating.

Other programs, more pixel-based, probably do this kind of thing natively. I recall some discussion relating to cell fill with Genetica.

</delurk>

Yup, FF definitely needs "Image Segmentation". Here's a super-ancient thread where we discussed it: Clicky!

(Note that Vlad did not seem to be very positive about this ever making an appearance in FF.)

</relurk>

REGION NODE REALLY WANT.

Sadly Vladimir Golovin's explanation of the problems is rather clear so I don't think we'll ever get a proper node. The best idea I have so far is a two step process:

- Step one generates a "coordinates texture" (similar to the one in the first post).
- In step two that texture is used in a separate filter to sample an image.

Of course step one is the tricky part. The reason it is a distinct pre-processing step is that it runs in an infinite loop, processing the same image from the command line over and over: in every iteration it identifies the next unprocessed cell then colors it by some logic. (Center coordinates, UV space fit to bounding box, etc, see Genetica examples in that other thread.)
We keep the first step running until the image is all colored. This part requires very little user input (only the selection of the coloring method) so it can run unattended.

The only real issue I can see is cell borders in the coordinates texture as bilinear filtering will produce artifacts during sampling an image. How bad it gets depends on the content of both the coordinates texture and the sampled image.

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Sadly Vladimir Golovin's explanation of the problems is rather clear so I don't think we'll ever get a proper node.

BOOO. lol.

Frankly though yes. Maybe in the ... future.

I asked this on the Substance Designer forums but the answer was a vague "Probably, I guess". Does anyone here have SD and willing to look around?

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Zoltan Erdokovy wrote: Does anyone here have SD and willing to look around?

I have SD (Substance Designer 4) but regrettably I have not been able to understand it how it works yet, as it seems to be much more complex node based than FF, and do not have time to learn how to use it.

I have seen the video tutorials, but it seems that is much more technical, complex and mainly for experienced professionals than for casual users