How would I detect gray/white pixels in a picture?

I am trying to write a function to detect white-like and gray-like pixels in a given colored picture. I am stuck on how to go about it. Any help is appreciated.

[yanqi liu]

yes，sir，may be upload your image file to analysis

Answer 1

[Walter Roberson]

Convert for HSV, check for "high" V (near 1) and "small" (near 0) S. You will need to decide on the exact boundaries, depending how "white like" or "gray like" you want to allow.

Answer 2

[KSSV]

REad about find. Gve the pixle value as zero and use find. This will give you the indices.

[y,x] = find(I==0) ;  % I is gray image 

[Ali Almakhmari]

But that would require me to manually identifiy the gray pixels and assign them to zero. Which is the thing I am trying to automate with this function.