Question

Is there any R function to convert grey scale image to binary image. There is one to convert from RGB to Grey but I want to convert Grey to Binary.

Answer 1

You didn’t say what class or “typeof” your data is, so I’m going to provide an answer in a simple case. Suppose your image is an array of integers. These integers range from 0 to, say 512 for a 9-bit greyscale image. You need to decide what the cutoff point is for 0 vs. 1 in your binary image. Then

bin_image <- round(grey_image/max(grey_image),0)

should do it. If your data range from 0 to 1, do a similar operation but adjust the rounding parameters.
Edit: ooops, I left out a choice of cutoff level. Replace max(grey_image) with K*max(grey_image) where K = 1 for cutting at half-max, K>1 to cut higher and K<1 to cut lower.