How I could detect all coordinates of points like in this image

[diegomage]

this is the image



and this is the point




Please help me with this problem

[snibgo]

What version of IM? On what platform?

The solution is to use "compare" with "-subimage-search".

[fmw42]

You can write to txt: format and exclude the black ones, assuming your image is not jpeg and has solid black for the background.

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convert image txt:- | grep -v "black"

This works on Unix and lists the coordinates and colors of all non-black pixels. I do not know if Windows has pipes or grep. One of the windows users can corroborate.

[snibgo]

But the required "point" is an image, a subimage.

[fmw42]

But the required "point" is an image, a subimage.

Sorry, I misunderstood and did not notice the smaller image. Snibgo's solution is then the correct one. You can then find all the brightest points in the second output image from the subimage-search compare. If on Unix-like systems, see my script maxima.

[diegomage]

But the required "point" is an image, a subimage.

Sorry, I misunderstood and did not notice the smaller image. Snibgo's solution is then the correct one. You can then find all the brightest points in the second output image from the subimage-search compare. If on Unix-like systems, see my script maxima.

very thankyou; could you send me the link of your script ?

[snibgo]

Again I ask: What version of IM? On what platform?

[diegomage]

Again I ask: What version of IM? On what platform?

I use 6.9.8.3
Version: ImageMagick 6.9.8-3 Q16 x86_64
I use linux ubuntu

[snibgo]

Code: Select all

compare -metric RMSE -subimage-search aO4kz.png oe5pC.png x.png

convert x-1.png -define identify:locate=maximum -identify NULL:

The output is:

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  Channel maximum locations:
  Gray: 65535 (1) 52,3 52,50 51,81

This gives the three locations of the top-left corner of the location where the subimage is found.

[fmw42]

Adding slightly to snibgo reply, you can tell IM how many maxima you want to return using -define identify:limit=X. The default is 3 as he showed. See http://www.imagemagick.org/script/identify.php. However, if the peaks are broad, you can get many values around a single peak. So the better way is to find each, one at a time, then write a small round black area over that maxima. Then search for the next one. I have a bash unix script, maxima, that does that. See my link below.

[snibgo]

The default is to find them all, eg:

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f:\web\im>%IM%convert -size 4x4 xc:White -define identify:locate=maximum -identify null:
  Channel maximum locations:
  Gray: 65535 (1) 0,0 1,0 2,0 3,0 0,1 1,1 2,1 3,1 0,2 1,2 2,2 3,2 0,3 1,3 2,3 3,3

In the OP's case, there were only three white pixels.

[fmw42]

The default is to find them all, eg:

I stand corrected. Thanks.

[diegomage]

Code: Select all

compare -metric RMSE -subimage-search aO4kz.png oe5pC.png x.png

convert x-1.png -define identify:locate=maximum -identify NULL:

The output is:

Code: Select all

  Channel maximum locations:
  Gray: 65535 (1) 52,3 52,50 51,81

This gives the three locations of the top-left corner of the location where the subimage is found.

very thankyou