Software for displaying and editing similar grayscale colors

Hi all, I need a software that would load an grayscale image, and display it like so:

Required features:
-it needs to have a big zoom, at least around 50x
-colors on all pixels must be always displayed in the center of the pixel and clearly visible
-and, of course, ability to pick and edit colors
Optional features:
-customizable font and grid colors
Any help appreciated!

Required features:
-it needs to have a big zoom, at least around 50x
-colors on all pixels must be always displayed in the center of the pixel and clearly visible
-and, of course, ability to pick and edit colors

Optional features:
-customizable font and grid colors
Any help appreciated!