#include "l_bitmap.h"

L_LTIMGCOR_API L_INT L_AutoTrimBitmap(pBitmap, uThreshold, uFlags)


pointer to the bitmap handle

L_UINT uThreshold;

 delta value for detecting blank space 

L_UINT32 uFlags;


Trims the current bitmap, removing blank space around the edges.




Pointer to the bitmap handle that references the bitmap to be trimmed.


Delta value for detecting blank space. Starting at each edge of the bitmap and evaluating toward the center, any change in intensity that is less than or equal to uThreshold is considered blank space. Valid values are 0 to 255.


Reserved for future use. Must be 0.



The function was successful.

< 1

An error occurred. Refer to Return Codes.


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.

Generally, this function is used for automatically trimming blank space from the edges of scanned documents.

Nevertheless, because this function uses changes in intensity to detect blank space, it can trim edges of any color or intensity.

If a region is defined for the bitmap, the region is also trimmed if necessary.

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.

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


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


Win32, x64, Linux.

See Also


L_GetAutoTrimRect, L_TrimBitmap, L_CopyBitmapRect, L_WindowLevel, L_AutoBinarizeBitmap, L_DynamicBinaryBitmap, L_AutoBinaryBitmap


Raster Image Functions: Doing Geometric Transformations


Processing an Image


This example loads an image and then AutoTrims the bitmap

L_INT AutoTrimBitmapExample(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 (MAKE_IMAGE_PATH(TEXT("clean.tif")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if(nRet !=SUCCESS) 
      return nRet; 
   /* AutoTrim the bitmap with 0 tolerance */ 
   nRet = L_AutoTrimBitmap ( &LeadBitmap, 0 , 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  
   return SUCCESS; 

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