The command you are looking for is
point(). This is very slow however, so it would be much wiser to use memblocks to solve this problem:
rem load the image
img=1
load image "filename",img
rem make a memblock out of the image
mem=1
make memblock from image mem,img
rem get dimensions of image
width=memblock dword(mem,0)
height=memblock dword(mem,4)
depth=memblock dword(mem,8)
rem make an array to store data into once read
dim pixel_color(width,height)
rem read in pixel data
pos=8
for x=0 to width-1
for y=0 to height-1
inc pos,4
pixel_color(x,y)=memblock dword(mem,pos)
next y
next x
rem clean up
delete image img
delete memblock mem
To get the individual red, green and blue colors, use this:
red=rgbr(pixel_color(x,y))
green=rgbg(pixel_color(x,y))
blue=rgbb(pixel_color(x,y))
The code above is untested, but I think it should work
TheComet