Looking for automatic measurement

I am brand new to image analysis, and I hope that doesn’t prevent me from asking my question in an effective manner. I am doing analysis of blade wear on paper machines and I am trying to see if I can save myself some time. I am currently using a screen caliper application to measure the amount of wear on the blades, which i measure with a proscope at 50x magnification. I have the “wear area” highlighted in the attached picture. The wear area is pretty recognizable as it has a much lighter color, and I always arrange the camera so that the wear is roughly horizontal. I could probalby 3D print an attachment for the proscope that makes the blade exactly horizontal on the blade every time if that would make the job easier. Is there a way using an application like imagej, icy, or any other open source software to automatically measure that lighter band and measure the width (top edge to bottom edge) of the ear area. On a busy day, I am doing roughly 500 of these at a time, so figuring out how to automate this process could save me hours. Any direction would be greatly appreciated on this, even if it is to documentation that i could read to help accomplish this task.