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I'm trying to make a 1bit (two colors) floyd-steinberg dithering on images but I'm getting artifacts/blemishes, I have tried hundreds of permutations so now I have to ask you guys if you can spot the mistake(s). Pseudo code from Wikipedia... https://en.wikipedia.org/wiki/Floyd–Steinberg_dithering My code... #include<GDIPlus.au3> HotKeySet("{ESC}", "_exit") _GDIPlus_Startup() Global $Image = _GDIPlus_BitmapCreateFromFile ("graytest.png") Global $Width = _GDIPlus_ImageGetWidth($Image), $Height = _GDIPlus_ImageGetHeight($Image) $Gui= GUICreate("Floyd-Steinberg Dithering", $Width, $Height) GUISetState() $Graphics = _GDIPlus_GraphicsCreateFromHWND($Gui) _GDIPlus_GraphicsDrawImageRect ($Graphics,$Image, 0, 0, $Width, $Height) For $y = 0 To $Height - 1 For $x = 0 To $Width - 1 $oldpixel = Dec(Hex(_GDIPlus_BitmapGetPixel($Image, $X, $Y), 2)) $newpixel = Round($oldpixel / 255) ? 0 : 1; _GDIPlus_BitmapSetPixel($Image, $X, $Y, String("0xFF" & Hex($newpixel*255, 2) & Hex($newpixel*255, 2) & Hex($newpixel*255, 2))) $quant_error = $oldpixel - $newpixel ;~ Consolewrite($quant_error & " " & @crlf) ;-------Floyd-Steinberg _GDIPlus_BitmapSetPixel($Image, $X+1, $Y, _GDIPlus_BitmapGetPixel($Image, $X+1, $Y ) + 7/16 * $quant_error) _GDIPlus_BitmapSetPixel($Image, $X-1, $Y+1, _GDIPlus_BitmapGetPixel($Image, $X-1, $Y+1) + 3/16 * $quant_error) _GDIPlus_BitmapSetPixel($Image, $X, $Y+1, _GDIPlus_BitmapGetPixel($Image, $X, $Y+1) + 5/16 * $quant_error) _GDIPlus_BitmapSetPixel($Image, $X+1, $Y+1, _GDIPlus_BitmapGetPixel($Image, $X+1, $Y+1) + 1/16 * $quant_error) ;-------Sierra2 ;~ _GDIPlus_BitmapSetPixel($Image, $X+1, $Y , _GDIPlus_BitmapGetPixel($Image, $X+1, $Y ) + 4/16 * $quant_error) ;~ _GDIPlus_BitmapSetPixel($Image, $X+2, $Y , _GDIPlus_BitmapGetPixel($Image, $X+2, $Y ) + 3/16 * $quant_error) ;~ _GDIPlus_BitmapSetPixel($Image, $X-1, $Y+1, _GDIPlus_BitmapGetPixel($Image, $X-1, $Y+1) + 1/16 * $quant_error) ;~ _GDIPlus_BitmapSetPixel($Image, $X, $Y+1, _GDIPlus_BitmapGetPixel($Image, $X, $Y+1) + 2/16 * $quant_error) ;~ _GDIPlus_BitmapSetPixel($Image, $X+1, $Y+1, _GDIPlus_BitmapGetPixel($Image, $X+1, $Y+1) + 3/16 * $quant_error) ;~ _GDIPlus_BitmapSetPixel($Image, $X+2, $Y+1, _GDIPlus_BitmapGetPixel($Image, $X+2, $Y+1) + 2/16 * $quant_error) ;~ _GDIPlus_BitmapSetPixel($Image, $X+3, $Y+1, _GDIPlus_BitmapGetPixel($Image, $X+3, $Y+1) + 1/16 * $quant_error) Next _GDIPlus_GraphicsDrawImageRect($Graphics, $Image, 0, 0, $Width, $Height); to see the errors quick instead of waiting for the whole image Next _GDIPlus_GraphicsDrawImageRect($Graphics, $Image, 0, 0, $Width, $Height) While GUIGetMsg <> - 3 Sleep(10) WEnd Func _exit() Exit EndFunc ;-------------------------------------------------------------------------------------------------------------- ;~ from Wikipedia article https://en.wikipedia.org/wiki/Floyd%E2%80%93Steinberg_dithering ;~ for each y from top to bottom ;~ for each x from left to right ;~ oldpixel := pixel[x][y] ;~ newpixel := find_closest_palette_color(oldpixel) ;~ pixel[x][y] := newpixel ;~ quant_error := oldpixel - newpixel ;~ pixel[x+1][y ] := pixel[x+1][y ] + 7/16 * quant_error ;~ pixel[x-1][y+1] := pixel[x-1][y+1] + 3/16 * quant_error ;~ pixel[x ][y+1] := pixel[x ][y+1] + 5/16 * quant_error ;~ pixel[x+1][y+1] := pixel[x+1][y+1] + 1/16 * quant_error ;~ find_closest_palette_color(oldpixel) = round(oldpixel / 255) ;-------------------------------------------------------------------------------------------------------------- If you comment the floyd-steinberg lines and uncomment the Sierra2 lines you can see that's much better without artifacts in the middle of the images, though it still has artifacts on the left side of the image, but it's mostly floyd I need working, any help? (dont mind the slow gdi+, I'll be using struct or c-dll when/if i get it working.) /edit, forgot the pic, but try with any pic /edit2, I will only be feeding it 8bit grayscale images)