I've added a new G'MIC filter Arrays & tiles / Extract objects.
It is quite experimental, but seems to be already useful in some situations.
It tries to automatically extract foreground objects from an image with a 'constant' colored background.
The extraction creates as many new layers as there are object detected.

Here is a typical example of use. Suppose you are interested to get each letter from an alphabet that you have found on the web, for instance this one :



Extracting each letter manually is a pain for people like me
And in this case, you cannot extract easily the shapes you are interested in, because they are not placed along a regular grid for instance.
So, now, what I can do is open G'MIC and select filter Arrays & tiles / Extract objects (of course, you need a refresh to see this filter appearing in your G'MIC) :



The green dots appearing in the preview is the point that must be set on background, it will define a reference color for the background, used to detect all foreground objects.
You set all the parameters (background point position, color tolerance, minimal size of detected objects, etc..), and you click OK.
And you get :



Here, I got 27 layers, i.e. all individual letters + the character.

Of course, this is not working so good when you have more complex backgrounds or shapes, but still it does a quite decent job and I'm sure this can be useful in many situations.

That's it, feel free to test and give feedback on this filter.

Wow, this is awesome.

Another example of use :



Very useful when you want to do sprite packing afterwards

thanks Rononours !

Minimal Area, is that value in pixels ?

Definitely awesome David. Just wish I can go from 1.5.6.1 beta to 1.5.6. Not sure what the issues are for the compile. Oh well; just spieling now.

edit:

Spieling's over; just tried samj's compile (though it's in the beta zip file, it's the full release) and it works fine. Happy I am.

I can't begin to tell you how many times I could have used this. It's wonderful. I just tried it with an image with a transparent background and it worked great for that too.

Thank you, thank you, David!

Wow, my mind is racing with ways this can be used!

Very cool since I have sprite tape too. Thier's Pan to Bow afterwards.

And why not. lol

Thanks for your feedback.

The minimal area is expressed as a percentage of the total number of pixel (width*height), so the preview
is almost accurate.

I love it for Sprite packing I must admit (that was the primary reason that decided me to code this filter by the way).
From this image :

I can render something like this, in less than 2 minutes :



Yes, this is ugly, but that was fast

Thanks for another neat filter!

Now that's way cool David.

excellent filter, David! Thank you

Thanks David this is excellent and goes right along Rob's "Break Apart Alpha" script.
Having both these filters for object extraction is awesome because both work in a different way.

Ha interesting Rod. My filter miserably fails with your gear image, that's an interesting challenge.
I'll have a look.

How about a foreground select for not so flat backgrounds, based on the b&w recolorize filter? Was thinking of doing that myself but still busy with other things - you would just paint roughly on foreground/background with one colour for each. Maybe there's already a filter like that and I missed it though.

Separating letters or objects into layers for GBR (Gimp Brush) saving is much easier now for sure!



GBR Rusted-Pipe zip attached.




David i think probably because of the same reason as Robs. He had to add a threshold setting for the shadows around the objects.

I've done some small modifications to the filter :

- Improvement of the detection algorithm.
- Added few parameters to better control the segmentation step (opacity threshold, connectivity).
- Added a progress bar.

Looks like this now :