Width% = 200
      Height% = 200

      DIM out&(Width%-1, Height%-1, 2)

      VDU 23,22,Width%;Height%;8,16,16,128
      *DISPLAY Lena
      OFF

      DIM filter%(2, 2)
      filter%() = -1, -1, -1, -1, 12, -1, -1, -1, -1

      REM Do the convolution:
      FOR Y% = 1 TO Height%-2
        FOR X% = 1 TO Width%-2
          R% = 0 : G% = 0 : B% = 0
          FOR I% = -1 TO 1
            FOR J% = -1 TO 1
              C% = TINT((X%+I%)*2, (Y%+J%)*2)
              F% = filter%(I%+1,J%+1)
              R% += F% * (C% AND &FF)
              G% += F% * (C% >> 8 AND &FF)
              B% += F% * (C% >> 16)
            NEXT
          NEXT
          IF R% < 0 R% = 0 ELSE IF R% > 1020 R% = 1020
          IF G% < 0 G% = 0 ELSE IF G% > 1020 G% = 1020
          IF B% < 0 B% = 0 ELSE IF B% > 1020 B% = 1020
          out&(X%, Y%, 0) = R% / 4 + 0.5
          out&(X%, Y%, 1) = G% / 4 + 0.5
          out&(X%, Y%, 2) = B% / 4 + 0.5
        NEXT
      NEXT Y%

      REM Display:
      GCOL 1
      FOR Y% = 0 TO Height%-1
        FOR X% = 0 TO Width%-1
          COLOUR 1, out&(X%,Y%,0), out&(X%,Y%,1), out&(X%,Y%,2)
          LINE X%*2,Y%*2,X%*2,Y%*2
        NEXT
      NEXT Y%

      REPEAT
        WAIT 1
      UNTIL FALSE