Compute thickness of a layer

I would like to compute the thickness of a layer in an image (image_1.png). I would like to do this by computing the pixel value in the top layer subtracted by the pixel value in the corresponding bottom layer and averaged over the entire layer . Can someone help me how i could proceed with this?

Thank you

[Image Analyst]

A little challenging because the top layer is so faint, but I could give it a shot if you attach the original image without the yellow arrow annotation.

[Tri Rowstenkowski]

Thanks for your reply. I have uploaded two images.

[Image Analyst]

Well the two images you added look completely different. I don't even know what to TRY to find in those. You're going to have to add annotated versions of those. Is the field of view on all 3 images the same? It kind of looks like the first one is really zoomed in with a smaller field of view.

[Tri Rowstenkowski]

The bright pixels together form a layer of the lumen (seen in image_4.jpg). I would like to compute its thickness(from green line to yellow line). Segmentation edges at pixel i, with the superscript top and bottom indicate the top and bottom edges, respectively and n is the total pixel number.

I would really appreciate your help in computing the thickness for image_2.png or image_3.png.

[Tri Rowstenkowski]

@Image Analyst Can you please help me?