Built-in Conversion

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

1. Define the following global variables:

    HANDLE ClrHandle;   
    CONVERSION_PARAMS params;   
    WHITEPOINT WPoint;   
    L_UCHAR *pRGBData;   
    L_UCHAR *pLABData;   
    L_INT nWidth;   
    L_INT nHeight;   
    L_INT nInAlign;   
    L_INT nOutAlign; 

2. Set the conversion options by filling a CONVERSION_PARAMS structure:

    ZeroMemory(&params, sizeof(CONVERSION_PARAMS));      
    params.pWpoint = &WPoint;   
    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; 

3. Initialize the color conversion handle with L_ClrInit():

   L_ClrInit(&ClrHandle, CCS_RGB, CCS_LAB, &params);

4. Convert from RGB to CIELab:

   L_ClrConvert(ClrHandle, pRGBData, pLABData, nWidth, nHeight, nInAlign, nOutAlign);

5. At the end, free the color conversion handle:

   L_ClrFree(ClrHandle);