Built-in Conversion (Delphi 4.0)

The Color Conversion C API provides built-in conversion. To do a built-in conversion, follow the steps below:

  1. At the beginning of the Unit1 file, add LTDLLUNT, LTDLLTYP, and LTDLLDEF to the uses section.

  2. Use the following code to perform the built-in conversion:

    function TForm1.Builtin_RGBToLAB({in}pSrcRGB, {out}pDstLAB: Pointer; {in}nWidth, {in}nHeight: Integer) : {ret}Integer; 
    var 
    ClrHandle : THandle;           (* color handle           *) 
    params    : CONVERSION_PARAMS; (* conversion params      *) 
    WPoint    : WHITEPOINT ;       (* white point definition *) 
    ret       : Integer;           (* return value           *) 
    begin 
    (* 
    ****************************************************************** 
    * Simple conversion from RGB to CIELab using built-in conversion * 
    * Parameters :                                                   * 
    * pSrcRGB : 24 bit RGB data, this is the input image data        * 
    * pDstLAB : 24 bit CIELab data, this is the output image data    * 
    * nWidth  : Width of the image                                   * 
    * nHeight : Height of the image                                  * 
    * Returns SUCCESS when successful or error code else             * 
    ****************************************************************** 
    *) 
    (* initialize the conversion structure *) 
    ZeroMemory(Pointer(@params), SizeOf(CONVERSION_PARAMS)); 
    (* set the whitepoint *) 
    params.pWpoint := @WPoint; 
    (* set up default conversion data *) 
    params.uStructSize  := sizeof(CONVERSION_PARAMS); 
    params.pWpoint.nWhitePoint     := CIELAB_D50; 
    params.nQuantization  := 8; 
    params.nMethod  := USE_BUILTIN; 
    params.nActiveMethod  := USE_BUILTIN; 
    params.pWpoint.xWhite  := 0.0; 
    params.pWpoint.yWhite  := 0.0; 
    (* initialize the conversion engine *) 
    ret := L_ClrInit(@ClrHandle, 
    CCS_RGB, 
    CCS_LAB, 
    @params); 
    (* do we have a valid handle *) 
    if ret <> SUCCESS then 
       Result := ret 
    else 
       begin 
    (* do the conversion from RGB to CIELab *) 
    ret := L_ClrConvert (ClrHandle, 
    pSrcRGB, 
    pDstLAB, 
    nWidth, 
    nHeight, 
    0, 
    0); 
    if ret <> SUCCESS then 
       begin 
    (* free before leaving *) 
    L_ClrFree (ClrHandle); 
    Result := ret; 
    end 
    else 
       begin 
    (* do not forget to free every thing *) 
    ret := L_ClrFree (ClrHandle); 
    Result := ret; 
    end; 
    end; 
    end; 

Help Version 22.0.2021.10.29
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LEADTOOLS Color Conversion C API Help
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© 1991-2021 LEAD Technologies, Inc. All Rights Reserved.