Legacy ImageMagick Discussions Archive

Ok maybe cropping the individual boxes is not a good idea after all.
To reset the problem, this is my larger image and I want to classify all boxes in this image as ticked or non-ticked.



Fred, what would you use?

@Fred: I tried, it doesn't work well. I read your solution in this thread: https://www.imagemagick.org/discourse-server/viewtopic.php?t=31295 I have to hand-tune the threshold to make it work. I also read this, maybe I should use morphology? http://www.imagemagick.org/Usage/compare/#sub-image Looks ...

I'm not trying to find the location of the boxes. I already know the location of the boxes (sometimes there is a small deviation of some pixels which is the X/Y shift you see in the group of the 4 images) and crop them up in individual images. What I want to know is whether the cropped image of the ...

Sorry, edited the post, you're too fast (thanks!) and I was sloppy! I don't have fully black squares anymore, I only ticked check boxes and non ticked ones (empty).

I want to match this image in one of these 4 boxes:

I already crop separate images of each checkbox. Here are some examples: https://i.imgur.com/MFpQLuj.png https://i.imgur.com/k8cmiUZ.png https://i.imgur.com/XuaS5xa.png https://i.imgur.com/qTTGiTP.png Do you think subimage search would work better/faster than the "counting black pixels on every Y ...

@Fred: Wouldn't that be slower?

edit: also less reliable because of the X, Y shift.

I mean count (or calculate the sum of) the black black pixels on each Y.
That way it will be something like:

Tried it and while it seems to work ok most of the time, sometimes there is a small shift (translation i X or Y) in the crop of the checkbox which is problematic for accuracy. The "[peak black pixel sum] ... [low black pixel sum] ... [peak black pixel sum]" would be better I think. Don't know how to ...

I know where it is but not exact to the pixel level. There might be some x, y translation.
How do I find the mean lightness?

I had an idea, check it with histogram distribution? The checkbox with a check won't have 2 sudden drops in the histogram. I mean: - the edges of the rectangle have "max black pixels" - the "inside" of the checked rectangle has "less than max black pixels" - the "inside" of the unchecked rectangle ...

Yeah, I was just wondering if this alternative approach is possible.

Any ideas?

Thanks for the replies!

I was also thinking, how can detect an actual rectangle? Like 4 edges and only white pixels "inside"?

How can I detect if the checkbox in an image is checked or not?

Example with checkbox checked:
http://imgur.com/a/3VPuC

Example with checkbox not checked:
http://imgur.com/DwQvB4X

Note: I'm not embedding the images because the one with the checkbox checked appears weird.