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L_ManualPerspectiveDeskew

Summary

Corrects the view perspective.

Syntax

#include "ltimgcor.h"

L_LTIMGCOR_API L_INT L_ManualPerspectiveDeskew(pBitmap, InPoints, ppOutBitmap)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to be transformed.

pMANUALPERSPECTIVEDESKEWPOINTS InPoints

Pointer to ManualPerspectiveDeskewPoints structure that contains a list of points that will be transformed to match the location of the mapped points list

pBITMAPHANDLE* ppOutBitmap

Pointer of pointer to bitmap handle that contains the deskewed image.

Returns

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

Comments

The L_ManualPerspectiveDeskew can change the specified image. To keep the original image unchanged, use this function on a copy.

Typically, this function is used as a step when preprocessing images from digital cameras. It changes the image based on a view perspective equation, taking the depth of the objects into account as well as their relative dimensions.

It is best to choose input points that are far away from each other.

Use the L_ManualPerspectiveDeskew, L_Keystone, or L_PerspectiveDeskew / L_PerspectiveDeskewExt function if there is a planar deformation along all three axes. Use the L_UnWarp function if there is a cylindrical deformation. Use the L_DeskewBitmap function if there is deformation along both the x- and y- axes.

This function can only process entire images. It does not support regions.

This function supports 24- and 36-bit color images and 8- and 16-bit grayscale images.

This command supports signed/unsigned images.

Required DLLs and Libraries

LTIMGCOR
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 applies manual perspective deskew filter.

L_INT ManualPerspectiveDeskewFilterBitmapExample(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("cannon.jpg")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   int Width = LeadBitmap.Width; 
   int Height = LeadBitmap.Height; 
 
   /* Apply manual perspective deskew filter to move down the top right corner by half of the image height*/ 
   MANUALPERSPECTIVEDESKEWPOINTS manual3ddeskewpoints; 
   manual3ddeskewpoints.InputPoints[0].x = 0; manual3ddeskewpoints.InputPoints[0].y = 0; 
   manual3ddeskewpoints.InputPoints[1].x = Width - 1; manual3ddeskewpoints.InputPoints[1].y = 0; 
   manual3ddeskewpoints.InputPoints[2].x = 0; manual3ddeskewpoints.InputPoints[2].y = Height - 1; 
   manual3ddeskewpoints.InputPoints[3].x = Width - 1; manual3ddeskewpoints.InputPoints[3].y = Height - 1; 
 
   manual3ddeskewpoints.MappingPoints[0].x = 0; manual3ddeskewpoints.MappingPoints[0].y = 0; 
   manual3ddeskewpoints.MappingPoints[1].x = Width - 1; manual3ddeskewpoints.MappingPoints[1].y = Height / 2; 
   manual3ddeskewpoints.MappingPoints[2].x = 0; manual3ddeskewpoints.MappingPoints[2].y = Height - 1; 
   manual3ddeskewpoints.MappingPoints[3].x = Width - 1; manual3ddeskewpoints.MappingPoints[3].y = Height - 1; 
 
   pBITMAPHANDLE pOutBitmap = NULL; 
   nRet = L_ManualPerspectiveDeskew(&LeadBitmap, &manual3ddeskewpoints, &pOutBitmap); 
 
   if (nRet != SUCCESS) 
   { 
      //free bitmap 
      if (LeadBitmap.Flags.Allocated) 
         L_FreeBitmap(&LeadBitmap); 
 
      return nRet; 
   } 
 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), pOutBitmap, FILE_BMP, 24, 0, NULL); 
 
   L_FreeManualPerspectiveDeskewBitmap(pOutBitmap); 
 
   //free bitmap 
   if (LeadBitmap.Flags.Allocated) 
      L_FreeBitmap(&LeadBitmap); 
 
   return nRet; 
}