glReadPixels() arguments

The values of the function glRasterPos*() are measured from the current coordinate system.If we use from the glDrawPixels() or glBitmap() then the bottom-left of the picture is depend on the glRasterPos*() and so is depend on the transformations–I mean that the transformations can change the bottom left of the picture.
My question is about the glReadPixels().I believe that The first two arguments of this function are depend on the current coordinate system.But the width and height values are depend on the pixel’s width and height of our screen–And so, the transformations don’t change them.Am i correct?

Both the origin and size of glReadPixels are in window coordinates and are not affected by any transformations.