Legacy ImageMagick Discussions Archive

I am in trouble finding multipe instances of same sub-image inside this image:



"compare" confuses "1" with "2" in IM V6, and in V7 it simply fails saying the two images are too different.





I tried several command lines, for example:
Tried with IM 6.6.6 and IM 7.0.8 in Windows 10.

I need to ignore color differences, hence this image would have 2 instances of each number.

I also had a look at this page but I don't know how to translate BASH to DOS, and word wrap does not help...
https://www.imagemagick.org/Usage/compare/#difference

edit: added sub-images

Please link to your subimage 2r.png.

On using IM under Windows, see http://www.imagemagick.org/Usage/windows/

Sorry I forgot the subimages. I just added them, anyway they're just croppings of the main image.

No, they are not just croppings. They are much larger than in the main image. IM will not find any exact matches.

I don't understand why the subimages look bigger in the browser, they are just 8x10 images!
This is what I see on my PC, maybe I messed up something while uploading?!?

I added "dimensions" column to explorer window... and something weird appeared!
I'll do a global check to eventually have all images properly sized and I'll report...

Ok now I got the right cropped images:











Full image:


I tried with "2": while there are "2" in the base image, I get good results; but after each finding I delete the "2" and restart the search; after the "2" are finished, IM starts "finding" 1, 7 and other numbers.

So, I have two questions:
- how do I automatically get all instances of same number searched, rather than manually deleting each found number from original image and searching again?
- how do I find only exact matches, or at least 95% matches?

So 2r.png is 20 pixels high, and numeri-tutti.png is only 30 pixels high. This is less than twice the height of the subimage, but it should be more than twice.

the 2r.png I uploaded was wrong, please look at new uploaded images: 0g.png to 9g.png

You said "I need to ignore color difference" but IM won't ignore the colours. If you want each subimage to be found twice, you need to pre-process the images so that each subimage actually does occur twice in the main image.

As I have just two colors, I think it will be faster replicating the check for each color.
So now we can assume for now that I only want to find yellow numbers.
Same questions apply:

- how do I automatically get all instances of same number searched, rather than manually deleting each found number from original image and searching again?
- how do I find only exact matches, or at least 95% matches?

jumpjack wrote:- how do I automatically get all instances of same number searched, rather than manually deleting each found number from original image and searching again?

"compare -subimage-search" finds the best match. If you want the next-best match, you can overpaint the pixels in the main image where the subimage was found, and run the search again.

jumpjack wrote:- how do I find only exact matches, or at least 95% matches?

"compare -subimage-search" finds the best match, and gives a score. For example: The best match has the top-left of the subimage at (32,20) in the main image. The score (in parentheses) is 0, which for RMSE means a perfect match. The scrore is between 0 and 1. Your script might reject any score worse than 0, or worse than 0.05, or whatever.

snibgo wrote: ↑2019-07-14T10:38:10-07:00 If you want the next-best match, you can overpaint the pixels in the main image[...]

This is what I am doing, I hoped there was a cleaner method...

snibgo wrote: ↑2019-07-14T10:38:10-07:00

jumpjack wrote:- how do I find only exact matches, or at least 95% matches?

[...]. The score (in parentheses) is 0, which for RMSE means a perfect match. The scrore is between 0 and 1. Your script might reject any score worse than 0, or worse than 0.05, or whatever.

thanks

If you are using a Unix variant of Imagemagick, then see my script maxima at my link below. It will find multiple instances of matches that have the top compare subimage-search scores. It is a bash unix shell script that does something similar to what user snibgo just suggested.

Also see https://imagemagick.org/script/identify.php
You can apply that to the compare score image from subimage-search of compare. The second output image.

That will find the top 3 values in the compare score image. But you have to mask out the locations of each match so the it does not just find the one pixel offset with a high score. So you have to write a loop, find the max, mask over that region with black (as in my script), then use identify again. You do not have to run compare each time.