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LBitmap::Keystone

Summary

Performs inverse perspective transformation (keystoning) on an image.

Syntax

#include "ltwrappr.h"

virtual L_INT LBitmap::Keystone(pPoints, pOutBitmap)

Parameters

L_POINT* pPoints

Pointer to L_POINT that contains four polygon points to be mapped to rectangle.

pBITMAPHANDLE pOutBitmap

Pointer of pointer to the bitmap handle that represents the resultant rectified bitmap.

Returns

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

Comments

Frequently, images captured by portable devices are distorted because they are projected onto a surface at an angle. Vertical lines become slanted, etc. This function maps a polygon to a rectangle (an inverse perspective transformation), and can be used to correct the perspective of such images.

The input pPoints should contain 4 polygon points. These points will become the corners of the rectangle and the rest of the pixels are shifted accordingly.

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

This function supports 12 and 16-bit grayscale and 48 and 64-bit color images.

Required DLLs and Libraries

LTDIS
LTFIL
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.

Example

#if defined (LEADTOOLS_V19_OR_LATER) 
L_INT LBitmap__KeystoneExample(L_VOID) 
{ 
    L_INT nRet ; 
    LBitmap LeadBitmap ; 
 
    nRet = LeadBitmap.Load(MAKE_IMAGE_PATH(TEXT("Master.jpg")), 0,ORDER_BGR) ; 
    if(nRet !=SUCCESS) 
        return nRet ; 
 
    /* Apply a Keystone filter */ 
    pBITMAPHANDLE pOutBitmap = NULL ; 
    L_POINT pPoints[4] ; 
 
    pPoints[0].x =  94 ; 
    pPoints[0].y =  94 ; 
    pPoints[1].x = 306 ; 
    pPoints[1].y =  43 ; 
    pPoints[2].x = 318 ; 
    pPoints[2].y = 237 ; 
    pPoints[3].x =  98 ; 
    pPoints[3].y = 237 ; 
 
    nRet = LeadBitmap.Keystone(pPoints, &pOutBitmap); 
 
    if(pOutBitmap->Flags.Allocated) 
        L_FreeBitmap(pOutBitmap); 
 
    return nRet; 
} 
#endif // LEADTOOLS_V19_OR_LATER