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L_ContBrightIntBitmap

Summary

Applies contrast, brightness and intensity adjustments to enhance the image tonal range.

Syntax

#include "l_bitmap.h"

L_LTIMGCLR_API L_INT L_ContBrightIntBitmap (pBitmap, nContrast, nBrightness, nIntensity, uFlags);

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to change.

L_INT nContrast

Value that represents the amount of histogram stretching. The contrast ranges from -1000 to +1000. This value is divided internally by 1000. A positive value increases the contrast whereas a negative value decreases the contrast.

L_INT nBrightness

Value that represents the colors intensities scale factor. The brightness ranges from -1000 to 1000. This value is divided internally by 1000. A positive value increases (or lightens) the brightness of the bitmap image. A negative value decreases (or darkens) the brightness of the bitmap image.

L_INT nIntensity

Value that represents the amount of colors intensities shifting. The intensity ranges from -1000 to +1000. This value is divided internally by 1000. A positive value lightens the brightness pixels whereas a negative value darkens the brightness pixels.

L_UINT32 uFlags

Reserved for future use. Must be 0.

Returns

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

Comments

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.

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 in the Document and Medical Imaging toolkits.

It also can process the whole image or a region of the image. If a bitmap has a region, the effect is applied only to the region.

The transformations are applied in this order: Contrast, Brightness then Intensity. Were the three functions to be called separately, then after each function was applied calculated values less than 0 and more than 255 (for 8 bits per component for example) would be clamped to 0 and 255 respectively. Using this function, the values are accumulative and the final result would be clamped. In addition, this function is faster than calling each function separately.

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

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

Win32, x64, Linux.

Example

This example loads a bitmap and performs the adjustments.

L_INT ContBrightIntBitmapExample(L_VOID) 
{ 
   L_INT nRet; 
   BITMAPHANDLE LeadBitmap; /* Bitmap handle to hold the image. */ 
 
   /* Load the bitmap, keeping the bits per pixel of the file */ 
   nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("IMAGE1.CMP")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGRORGRAY, NULL, NULL); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   nRet = L_ContBrightIntBitmap(&LeadBitmap, -146, 385, 240, 0); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   //free bitmap 
   if (LeadBitmap.Flags.Allocated) 
      L_FreeBitmap(&LeadBitmap); 
 
   return SUCCESS; 
}