Floyd-Steinberg Dithering

[Kas Ob.]

You are really hardworking on this !

Are you familiar with CMOV instruction ?!!
Read about it from here https://www.felixcloutier.com/x86/cmovcc
Also search and research example for it and its usage, and trust me you will feel real good after that and your above code will go brrrrrrr faster.

eg. That part of clamping the slow one replacing values with

Code:

      if v < 0 then
        Blue := 0
      else if v > 255 then
        Blue := 255
      else
        Blue := v;

This could be two CMP and two CMOV, with 0 branching/jumping, will boost the speed nicely, by relieving branch prediction (removing the jmps) letting out-of-order-execution kick in unhindered.
instead of

Code:

               jle      @BlueZero            // Ist <= 0
               cmp      eax,255
               jbe      @BlueSet             // Ist <= 255
               mov      byte[edx],255        // Blauanteil = 255 setzen
               jmp      @Green               // Gr&#1100;nanteil errechnen
@BlueZero:     xor      eax,eax              // Blau = 0
@BlueSet:      mov      [edx],al             // Blauanteil speichern

Also you could ditch all that and try SSE or MMX , both are supported on CPUs for almost 3 decades (MMX) and no need to check for CPU compatibility for it, MMX will perform the all these operation on one pixel (4 colors) in parallel, the speed should be around 4 times than simple plain linear assembly.