Width% = 200
      Height% = 200

      VDU 23,22,Width%;Height%;8,16,16,128
      *display c:\lena

      FOR y% = 0 TO Height%-1
        FOR x% = 0 TO Width%-1
          rgb% = FNgetpixel(x%,y%)
          r% = rgb% >> 16
          g% = (rgb% >> 8) AND &FF
          b% = rgb% AND &FF
          l% = INT(0.3*r% + 0.59*g% + 0.11*b% + 0.5)
          PROCsetpixel(x%,y%,l%,l%,l%)
        NEXT
      NEXT y%
      END

      DEF PROCsetpixel(x%,y%,r%,g%,b%)
      COLOUR 1,r%,g%,b%
      GCOL 1
      LINE x%*2,y%*2,x%*2,y%*2
      ENDPROC

      DEF FNgetpixel(x%,y%)
      LOCAL col%
      col% = TINT(x%*2,y%*2)
      SWAP ?^col%,?(^col%+2)
      = col%