#include "ltimgkrn.h"

L_LTIMGKRN_API L_INT L_ImgKrnDetectDocument(bitmap, documentArea)

BITMAPHANDLE *bitmap; pointer to the bitmap handle
L_POINT *documentArea; the points that represent the document edges

Detects and obtains the points that represent the document edges in an image.

Parameter Description
bitmap Pointer to the bitmap handle referencing the bitmap to be processed.
documentArea An array of L_POINT that contains the points that represent the edges of the document that have been detected.


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


For the best results, the document's boundaries should be inside the captured view and have a different background color than the background of the captured view.

Use the results from L_DetectDocument as the input points for the L_ImgKrnPerspectiveCorrectionData structure, which is used by the L_ImgKrnManualPerspectiveCorrection function to correct the perspective of a captured image.

This function can be used if there is depth (z-axis) deformation as well as deformation along the x- and y- axes.

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 Imaging toolkits.

This function supports unsigned data images, but not signed ones.

This function does not support 32-bit grayscale images.

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.

Note: All functions with the L_ImgKrn prefix modify the underlying properties of the input BITMAPHANDLE, including but not limited to:

To avoid BITMAPHANDLE property fidelity loss, pass a copy of your BITMAPHANDLE to all L_ImgKrn* functions.

See Also

Functions: L_ImgKrnCopyImage, L_ImgKrnCreateImage, L_ImgKrnCropImage, L_ImgKrnDetectGlare, L_ImgKrnFromYUV, L_ImgKrnInvertImage, L_ImgKrnManualPerspectiveCorrection, L_ImgKrnRotateFlipImage, L_ImgKrnSignalToNoiseRatio

Raster Image Functions: Image Analysis


The following example loads a bitmap, and applies the 3D-perspective effect.

L_INT KrnDetectDocumentExample(L_VOID) 
   L_INT ret; 
   BITMAPHANDLE bitmap;       /* Bitmap handle to hold the loaded image. */ 
   L_POINT documentArea[4];   /* Document area region points*/ 
   /* Load the bitmap */ 
   ret = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("PerspectiveDeskew.jpg")), &bitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if (ret != SUCCESS) 
      return ret; 
   /* Apply L_ImgKrnDetectDocument and detect document region */ 
   ret = L_ImgKrnDetectDocument(&bitmap, documentArea); 
   // Check if document detected 
   if (ret == SUCCESS) 
      MessageBox(NULL, TEXT("Document detected"), TEXT("L_ImgKrnDetectDocument"), MB_OK); 
      MessageBox(NULL, TEXT("No document detected"), TEXT("L_ImgKrnDetectDocument"), MB_OK); 
   return ret; 

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