Delphi图像处理 -- 线性亮度/对比度调整

本文的线性亮度/对比度调整方法是在《改进的图像线性亮度调整方法》一文中线性亮度调整方法与《Delphi图像处理 -- Photoshop图像亮度/对比度调整》中的对比度调整方法基础上形成的，其原理和特点可参见这2篇文章：

过程定义：

  // 线性调整亮度，Value亮度值
  procedure ImageLineBrightness(var Data: TImageData; Value: Integer);
  // 图像线性亮度/对比度调整。参数同图像亮度/对比度调整过程
  procedure ImageLineBrightContrast(var Data: TImageData;
    Bright, Contrast: Integer; Threshold: LongWord); overload;
    {$IF RTLVersion >= 17.00}inline;{$IFEND}
  procedure ImageLineBrightContrast(var Dest: TImageData; const Source: TImageData;
    Bright, Contrast: Integer; Threshold: LongWord); overload;
    {$IF RTLVersion >= 17.00}inline;{$IFEND}
  function ImageLineBrightContrast(var Dest: TImageData; const Source: TImageData;
    Bright, Contrast: Integer; Threshold: LongWord;
    Callback: TImageAbort; CallbackData: Pointer): Boolean; overload;

代码实现：

procedure ImageLinebrightness(var Data: TImageData; Value: Integer);
asm
    push    ebp
		push	  esi
		push	  edi
   	push	  ebx
    test    edx, edx
    jz      @@Exit
    call    IsValid32
    jc      @@Exit
    push    eax
    mov     eax, edx
    call    ClacBrightContrast
    mov     esi, eax
    pop     eax
    call    SetDataRegs32
@@yLoop:
    push    ecx
@@xLoop:
    push    ecx
    mov     ecx, 3
@@rgbLoop:
    movzx   eax, [edi]
    mov     ebp, eax            // rgb = rgb + rgb * esi / 256
    imul    eax, esi
    sar     eax, 8
    add     eax, ebp
    jns     @@1
    xor     eax, eax
@@1:
    cmp     eax, 255
    jb      @@2
    mov     eax, 255
@@2:
    stosb
    loop    @@rgbLoop
    inc     edi
    pop     ecx
    loop    @@xLoop
    add     edi, ebx
    pop     ecx
    dec     edx
    jnz     @@yLoop
@@Exit:
   	pop	    ebx
		pop	   	edi
		pop	  	esi
    pop     ebp
end;

procedure LineBrightContrast(bright, contrast, threshold, cv, bv: Integer); pascal;

  procedure LineBright;
  asm
    cmp     bright, 0
    je      @@end
    mov     ecx, eax            // rgb = rgb + rgb * bv / 256
    imul    eax, bv
    sar     eax, 8
    add     eax, ecx
    jns     @@end
    xor     eax, eax
  @@end:
  end;

var
  height, count: Integer;
  dstOffset, srcOffset: Integer;
asm
    mov     height, edx
    mov     dstOffset, ebx
    mov     srcOffset, eax
    mov     ebx, contrast       // ebx = contrast
    mov     edx, threshold
@@yLoop:
    push    ecx
@@xLoop:
    push    ecx
    mov     count, 3
@@rgbLoop:
    movzx   eax, [esi]          // eax = rgb
    test    ebx, ebx
    jz      @@21                // if (contrast > 0)
    js      @@10                // {
    call    LineBright          //   rgb = rgb + rgb * bv / 256
    cmp     ebx, 255
    jl      @@15                //   if (contrast >= 255)
    cmp     eax, edx            //   {
    jl      @@3                 //     rgb = rgb >= threshold? 255 : 0
    mov     eax, 255            //     goto @@next
    jmp     @@next              //   }
@@3:                            // }
    xor     eax, eax
    jmp     @@next
@@10:
    cmp     ebx, -255           // else if (contrast <= -255)
    jg      @@15                // {
    mov     eax, edx            //   rgb = threshold; goto @@20
    jmp     @@20                // }
@@15:
    mov     ecx, eax            // rgb = rgb + (rgb - threshold) * cv / 256
    sub     eax, edx
    imul    eax, cv
    sar     eax, 8
    add     eax, ecx
    jns     @@20
    xor     eax, eax
@@20:
    test    ebx, ebx
    jg      @@22
@@21:
    call    LineBright          // if (contrast <= 0) rgb = rgb + rgb * bv / 256
@@22:
    cmp     eax, 255
    jbe     @@next
    mov     eax, 255
@@next:
    stosb
    inc     esi
    dec     count
    jnz     @@rgbLoop
    pop     ecx
    movsb
    dec     ecx
    jnz     @@xLoop
    add     edi, dstOffset
    add     esi, srcOffset
    pop     ecx
    dec     height
    jnz     @@yLoop
end;

function ImageLineBrightContrast(var Dest: TImageData; const Source: TImageData;
  Bright, Contrast: Integer; Threshold: LongWord;
  Callback: TImageAbort; CallbackData: Pointer): Boolean;
var
  cv, bv: Integer;
begin
  Result := False;
  if ImageEmpty(Dest) or ImageEmpty(Source) then Exit;
  if Threshold > 255 then Threshold := 255;
  cv := ClacBrightContrast(Contrast);
  bv := ClacBrightContrast(Bright);
  if Assigned(Callback) then
    Result := ExecuteAbort(Dest, Source, @LineBrightContrast,
      [Bright, Contrast, Threshold, cv, bv], Callback, CallbackData)
  else
    Result := ExecuteProc(Dest, Source, @LineBrightContrast,
      [Bright, Contrast, Threshold, cv, bv]);
end;

procedure ImageLineBrightContrast(var Dest: TImageData; const Source: TImageData;
  Bright, Contrast: Integer; Threshold: LongWord);
begin
  ImageLineBrightContrast(Dest, Source, Bright, Contrast, Threshold, nil, nil);
end;

procedure ImageLineBrightContrast(var Data: TImageData;
  Bright, Contrast: Integer; Threshold: LongWord);
begin
  ImageLineBrightContrast(Data, Data, Bright, Contrast, Threshold, nil, nil);
end;

代码中对比度调整代码见《Delphi图像处理 -- Photoshop图像亮度/对比度调整》。

文章中所用数据类型及一些过程见《Delphi图像处理 -- 数据类型及内部过程》和《Delphi图像处理 -- 图像像素结构与图像数据转换》。

尽管我十分努力，但水平有限，错误在所难免，欢迎指正和指导。邮箱地址：

[e-mail]

本文代码于2010.5.20重新修订过。增加了拷贝形式的调整过程和响应回调函数的调整过程。代码中的ExecuteAbort过程和ExecuteProc过程见《Delphi图像处理 -- 图像像素结构与图像数据转换》。