L_ChangeBitmapContrast

#include "l_bitmap.h"

L_LTIMGCLR_API L_INT L_ChangeBitmapContrast(pBitmap, nChange)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_INT nChange;	/* amount of contrast change */

Increases or decreases the contrast of the image in a bitmap.

Parameter	Description
pBitmap	Pointer to the bitmap handle referencing the bitmap to be modified.
nChange	Amount of contrast change. Valid values are -1000 to +1000.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

To update a status bar or detect a user interrupt during execution of this function, refer to L_SetStatusCallback.

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 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

This Function changes the contrast of the image data. If the image has a LUT, the function will work on the LUT, not the image data.

If the image has a LUT and you want to work on the image data, set the UseLUT Flag in the BITMAPHANDLE structure to FALSE. Then, after calling the function, reset the UseLUT flag to TRUE as follows:

pBitmap->Flags.UseLUT = FALSE;

L_ChangeBitmapContrast(pBitmap, 250);

pBitmap->Flags.UseLUT = TRUE;

Required DLLs and Libraries

LTIMGCLR

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Windows 2000 / XP/Vista, Windows CE.

See Also

Functions:	L_ChangeBitmapIntensity, L_GammaCorrectBitmap, L_HistoContrastBitmap, L_StretchBitmapIntensity, L_RemapBitmapIntensity, L_InvertBitmap, L_ChangeBitmapHue, L_ChangeBitmapSaturation, L_HistoEqualizeBitmap, L_FillBitmap, L_GetPixelColor, L_PutPixelColor, L_GetBitmapHistogram, L_DlgContrast, L_WindowLevel, L_ChannelMix, L_DeinterlaceBitmap, L_DesaturateBitmap, L_LightControlBitmap, L_SmoothEdgesBitmap, L_LocalHistoEqualizeBitmap, L_AddWeightedBitmaps, L_ColorMergeBitmap, L_ColorSeparateBitmap, L_ConvertColorSpace, L_MultiplyBitmap, L_AutoColorLevelBitmap, L_ColorLevelBitmap, L_CorrelationBitmap, L_GrayScaleToDuotone, L_GrayScaleToMultitone, L_HolesRemovalBitmapRgn, L_SelectiveColorBitmap, L_SkeletonBitmap, L_ChangeHueSatIntBitmap, L_ColorReplaceBitmap, L_ColorThresholdBitmap, L_MathFunctionBitmap, L_SegmentBitmap, L_AdaptiveContrastBitmap, L_ApplyMathLogicBitmap, L_ColorIntensityBalance, L_ColorizeGrayBitmap, L_ContBrightIntBitmap, L_DigitalSubtractBitmap, L_DynamicBinaryBitmap, L_FunctionalLightBitmap, L_MultiScaleEnhancementBitmap, L_SelectBitmapData, L_ShiftBitmapData, L_AdjustBitmapTint, L_GammaCorrectBitmapExt
Topics:	Raster Image Functions: Modifying Intensity Values
	Changing Brightness and Contrast
	Raster Image Functions: Changing Brightness and Contrast

Example

For complete sample code, refer to the CHILD.C module of the DEMO example. This example loads a bitmap and increases its contrast.

 L_INT ChangeBitmapContrastExample(L_VOID)
{
   L_INT nRet;
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle to hold the loaded image. */
   /* Load the bitmap, keeping the bits per pixel of the file */
   nRet = L_LoadBitmap (TEXT("C:\\Program Files\\LEAD Technologies\\LEADTOOLS 15\\Images\\IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
   if(nRet !=SUCCESS)
      return nRet;
   /* Increase the contrast  by 25 percent  of the possible range */
   nRet = L_ChangeBitmapContrast(&LeadBitmap, 250 );
   if(nRet !=SUCCESS)
      return nRet;
   nRet = L_SaveBitmap(TEXT("C:\\Program Files\\LEAD Technologies\\LEADTOOLS 15\\Images\\Result.BMP"), &LeadBitmap, FILE_BMP, 24, 0, NULL);
   if(nRet !=SUCCESS)
      return nRet;
   //free bitmap 
   if(LeadBitmap.Flags.Allocated)  
      L_FreeBitmap(&LeadBitmap);  
   return SUCCESS;
}