How do I get the coordinates of a fingerprint image?

I have several images in which they have been located in different areas. I would like to find the coordination of where the image of fingerprint is started. Then I want to define a small window square in left top corner of the fingerprint.

Any idea?

Answer 1

[Image Analyst]

If you can threshold you can look for the lowest index in the binary image. Here's one of many ways

binaryImage = grayImage < someThreshold;
[rows, columns] = find(binaryImage);
topRow = min(rows);
leftColumn = min(columns);

Another way

verticalProfile = mean(binaryImage, 2);
topRow = find(verticalProfile, 1, 'first');
horizontalProfile = mean(binaryImage, 1);
leftColumn = find(horizontalProfile, 1, 'first');

[Klara]

Thanks, I segmented the image based on the variance. Therefore, foreground is area with higher variance. Then by the folowing script, I found the location of the top left corner.

    %   stats = regionprops(foreground,'Extrema');

   top_leftX = round(stats.Extrema(1,2));

   top_leftY = round(stats.Extrema(1,1));

How can I divide the image into blocks of 120x120 from that location?

[Image Analyst]

subImage = theImage(top_leftY:top_leftY+59, top_leftX:top_leftX+59);