LBitmap::ConvertToColoredGray

#include "ltwrappr.h"

virtual L_INT LBitmap::ConvertToColoredGray(RedFact, GreenFact, BlueFact, RedGrayFact, GreenGrayFact, BlueGrayFact, uFlags = 0)

Converts the class object's bitmap to a grayscale bitmap, then enhances the color components based on the specified parameters.

Returns

Comments

This function is more general than the LBitmap::GrayScaleExt function. LBitmap::ConvertToColoredGray can be used to give images an "sepia" look by adding a blue or brown color.

The summation (RedFact + GreenFact + BlueFact) must equal 1000. (Internally, the values are divided by 1000.)

For each pixel in the bitmap the red, green and blue values are modified by the RedFact, GreenFact and BlueFact parameters, respectively. This allows the user to give more weight to one color, essentially enhancing that color, before the pixel is converted to grayscale.

For example, if this function is called with the RedFact set to 500, the GreenFact set to 250 and the BlueFact set to 250, the red value of each pixel will get 50% of the weight when determining the grayscale value. The green value will get 25% of the weight and the blue value will get 25% of the weight when determining the grayscale value. This highlights or enhances the red in the bitmap, prior to conversion to grayscale. Upon conversion to grayscale, the red, green and blue components of the output pixel are the same. Call this value G. Therefore, the RGB values for the pixel would be (G, G, G).

Once the grayscale value for the pixel has been obtained, the red component of the output pixel can be further modified using the RedGrayFact value. The equation for this can be seen below:

Goutput-red = G + G * RedGrayFact / 1000

The green and blue components are found similarly, using the GreenGrayFact and the BlueGrayFact values, respectively.

Please note that the RedGrayFact, GreenGrayFact and BlueGrayFact values can be negative. A negative value results in a decrease in pixel intensity. A positive value results in an increase in pixel intensity.

If RedGrayFact = GreenGrayFact = BlueGrayFact = 0, then the output is the same as the output from the LBitmap::GrayScaleExt function.

This function supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available only in the Document/Medical toolkits.

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

This function does not support 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

Required DLLs and Libraries

See Also

Example

L_INT LBitmap__ConvertToColoredGrayExample(LBitmap & Bitmap, L_TCHAR * szFileName)
{
   L_INT nRet;
   
   nRet =Bitmap.Load(szFileName);
   if(nRet !=SUCCESS)
      return nRet;
   nRet =Bitmap.ConvertToColoredGray(100, 300, 600, 200, 300, 500);
   if(nRet !=SUCCESS)
      return nRet;
   return SUCCESS;
}