Applying the formula to determine the barcode

How to write the code to apply the formula to the image and the result is low-pass filtered. The red region is the highest intensity which corresponds to the barcode.

Formula:

Original Image

Processed Image

Answer 1

[Walter Roberson]

Perhaps

[FX, FY] = gradient(YourImage);
abs(FX) - abs(FY)

It appears to me that if the image were rotated 90 degrees then the value for any one pixel would switch sign, so you may wish to search for largest absolute values rather than just largest values.

[Kim]

How can search for largest absolute values?? Btw I was thinking of finding barcode in an angle?? Do you have any idea how to do that?

[Walter Roberson]

[maxval, maxloc] = max(abs(TheDiff(:)));

[maxr, maxc] = ind2sub(size(TheDiff), maxloc);