Delphi图像处理 -- RGB与HSL转换

阅读提示：

《Delphi图像处理》系列以效率为侧重点，一般代码为PASCAL，核心代码采用BASM。

《C++图像处理》系列以代码清晰，可读性为主，全部使用C++代码。

尽可能保持二者内容一致，可相互对照。

本文代码必须包括文章《Delphi图像处理 -- 数据类型及公用过程》中的ImageData.pas单元。

const
  _fc0: Single    = 0.0;
  _fcd5: Single   = 0.5;
  _fc1: Single    = 1.0;
  _fc2: Single    = 2.0;
  _fc6: Single    = 6.0;
  _fc60: Single   = 60.0;
  _fc255: Single  = 255.0;
  _fc360: Single  = 360.0;
  _fc510: Single  = 510.0;

procedure ColorToHSL(var H, S, L: Single; Color: TARGB);
var
  rgbMax: LongWord;
asm
    push      eax
    push      edx
    push      ecx
    movzx     ecx, Color.TARGBQuad.Blue
    movzx     edx, Color.TARGBQuad.Green
    movzx     eax, Color.TARGBQuad.Red
    cmp       ecx, edx        // ecx = rgbMax
    jge       @@1             // edx = rgbMin
    xchg      ecx, edx
@@1:
    cmp       ecx, eax
    jge       @@2
    xchg      ecx, eax
@@2:
    cmp       edx, eax
    cmova     edx, eax
    mov       rgbMax, ecx
    mov       eax, ecx
    add       ecx, edx        // ecx = rgbMax + rgbMin
    sub       eax, edx        // delta = rgbMax - rgbmin
    cvtsi2ss  xmm0, ecx
    divss     xmm0, _fc510
    pop       edx
    movss     [edx], xmm0     // *L = (rgbMax + rgbMin) / 255 / 2
    jnz       @@3
    pop       ecx             // if (delta == 0)
    pop       edx             // {
    mov       [ecx], eax      //   *H = *S = 0
    mov       [edx], eax      //   return
    jmp       @@Exit          // }
@@3:
    comiss    xmm0, _fcd5
    jb        @@4
    neg       ecx
    add       ecx, 510        // if (L < 128) ecx = 510 - ecx
@@4:
    pop       edx
    cvtsi2ss  xmm0, eax
    cvtsi2ss  xmm1, ecx
    movaps    xmm2, xmm0
    divss     xmm0, xmm1
    movss     [edx], xmm0     // *S = delta / ecx
    mov       eax, rgbMax
    cmp       al, Color.TARGBQuad.Red
    jne       @@5
    movzx     eax, Color.TARGBQuad.Green
    movzx     edx, Color.TARGBQuad.Blue
    xor       ecx, ecx        // if (R == rgbMax) eax = G - B; add = 0
    jmp       @@7
@@5:
    cmp       al, Color.TARGBQuad.Green
    jne       @@6
    movzx     eax, Color.TARGBQuad.Blue
    movzx     edx, Color.TARGBQuad.Red
    mov       ecx, 120         // if (G == rgbMax) eax = B - R; add = 120
    jmp       @@7
@@6:
    movzx     eax, Color.TARGBQuad.Red
    movzx     edx, Color.TARGBQuad.Green
    mov       ecx, 240         // if (B == rgbMax) eax = R - G; add = 240
@@7:
    sub       eax, edx
    cvtsi2ss  xmm0, eax
    cvtsi2ss  xmm1, ecx
    mulss     xmm0, _fc60
    divss     xmm0, xmm2
    addss     xmm0, xmm1      // H = eax * 60 / delta + add
    comiss    xmm0, _fc0
    jae       @@8
    addss     xmm0, _fc360
@@8:
    pop       eax
    movss     [eax], xmm0
@@Exit:
end;

function HSLToColor(H, S, L: Single): TARGB;
asm
    movss     xmm0, H
    comiss    xmm0, _fc0
    jae       @@1
    addss     xmm0, _fc360
    jmp       @@2
@@1:
    comiss    xmm0, _fc360
    jb        @@2
    subss     xmm0, _fc360
@@2:
    movss     xmm3, _fc1
    divss     xmm0, _fc60
    cvtss2si  edx, xmm0       // index = Round(H)
    cvtsi2ss  xmm1, edx
    subss     xmm0, xmm1      // extra = H - index
    comiss    xmm0, _fc0      // if (extra < 0) // 如果index发生五入
    jae       @@3             // {
    dec       edx             //   index --
    addss     xmm0, xmm3      //   extra ++
@@3:                          // }
    test      edx, 1
    jz        @@4
    movaps    xmm1, xmm0
    movaps    xmm0, xmm3
    subss     xmm0, xmm1      // if (index & 1) extra = 1 - extra
@@4:
    movss     xmm2, S
    movss     xmm4, L
    minss     xmm2, xmm3
    minss     xmm4, xmm3
    maxss     xmm2, _fc0
    maxss     xmm4, _fc0
    pslldq    xmm0, 4         //            max  mid  min
    movlhps   xmm0, xmm3      // xmm0 = 0.0 1.0 extra 0.0
    movaps    xmm1, xmm0
    subss     xmm3, xmm2
    movss     xmm2, _fcd5
    pshufd    xmm2, xmm2, 0
    pshufd    xmm3, xmm3, 0
    subps     xmm1, xmm2
    mulps     xmm1, xmm3
    subps     xmm0, xmm1      // xmm0 = xmm0 - (xmm0 - 0.5) * (1.0 - S);
    movaps    xmm1, xmm0
    subss     xmm4, xmm2
    mulss     xmm4, _fc2      // xmm4 = (L - 0.5) * 2
    comiss    xmm4, _fc0
    jb        @@5
    movss     xmm0, _fc1
    pshufd    xmm0, xmm0, 0
    subps     xmm0, xmm1      // if (xmm4 >= 0) xmm0 = 1 - xmm0
@@5:
    movss     xmm3, _fc255
    pshufd    xmm4, xmm4, 0
    pshufd    xmm3, xmm3, 0
    mulps     xmm0, xmm4
    addps     xmm0, xmm1
    mulps     xmm0, xmm3      // xmm0 = (xmm0 + xmm0 * xmm4) * 255
    jmp       @@jmpTable[edx*4].Pointer
@@jmpTable:   dd  offset  @@H60
              dd  offset  @@H120
              dd  offset  @@H180
              dd  offset  @@H240
              dd  offset  @@H300
              dd  offset  @@H360
@@H360:                       // 300 - 359
    pshufd    xmm0, xmm0, 11100001b
    jmp       @@H60
@@H300:                       // 240 - 299
    pshufd    xmm0, xmm0, 11010010b
    jmp       @@H60
@@H240:                       // 180 - 239
    pshufd    xmm0, xmm0, 11000110b
    jmp       @@H60
@@H180:                       // 120 - 179
    pshufd    xmm0, xmm0, 11001001b
    jmp       @@H60
@@H120:                       // 60 - 119
    pshufd    xmm0, xmm0, 11011000b
@@H60:                        // 0 - 59
    cvtps2dq  xmm0, xmm0
    packssdw  xmm0, xmm0
    packuswb  xmm0, xmm0
    movd      eax, xmm0
    or        eax, 0ff000000h
end;

《Delphi图像处理》系列使用GDI+单元下载地址和说明见文章《GDI+ for VCL基础 -- GDI+ 与 VCL》。

因水平有限，错误在所难免，欢迎指正和指导。邮箱地址：maozefa@hotmail.com

这里可访问《Delphi图像处理 -- 文章索引》。