WIDTH equ 640
	HEIGHT equ 480

	mov al, 11h	; set gfx mode to 640 x 480 x 2 color
	int 10h		; init gfx
	
	mov dx, HEIGHT

NEWROW  mov cx, WIDTH-1 
	dec dx

	mov al, 01h
	jmp PUTPIX	; always draw first pixel in new row

DOPIX   inc ah		; set BIOS function to getpixel
			
	inc dx          ; move cursor y++
	int 10h         ; get pixel color to AX

	dec dx		; move cursor back
	xor al, bl	; calculate new color

PUTPIX 	mov ah, 0Ch	; set BIOS funcion to putpixel
	mov bl, al	; save color 4 next pass 2 bufer BL
	int 10h		; draw pixel
		
	loop DOPIX
	
	test dx, dx	; end test
	jnz NEWROW

	xor ah, ah	
	int 16h         ; wait 4 key

	ret		; thx 2 hvge 4 knowhow