Colorful rectangle overlay on the grayscale image

[oguzk]

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. 

[BruceAmmons · Accepted solution]

A grayscale image does not have any color.  The only way to add color is to convert it to a RGB image.  There is no way around it.

Bruce

[oguzk]

Thank you for the information. I thought maybe there is a build function for this but apparently there is no. Thanks.