I am trying to create a rectangle overlay(preferably red), therefore I am using "IMAQ Overlay Rectangle" tool. But the overlay is nondestructive so I needed to use "IMAQ Merge Overlay" to overwrite on the image. However, after this tool output image is getting RGB format. I need grayscale image. Is there any way to overwrite colorful rectangle on the grayscale image. Thanks in advance, every suggestion is appreciated.