Convert long/lat to pixel x/y on a given picture

Question

I have a city map of Moscow. We modified a Google Maps image with some artistic elements, but the relation between GPS coordinates and pixels remains the same.

Answer 1

If each pixel is assumed to be of the same area then the following article about converting distances to longitude/latitude co-ordinates may be of some help to you:

http://www.johndcook.com/blog/2009/04/27/converting-miles-to-degrees-longitude-or-latitude/