rgb(&h12, &h34, &h56, &h78) equals to val("&h12345678")
so you can use val("&haarrggbb") for color codes (aa means alpha value)
rgbread gspoit(x,y) out aa,rr,gg,bb: ? format$("%02x%02x%02x%02x", aa,rr,gg,bb)
gives you the color code of the graphic point x, y