#include "ltwrappr.h"

virtual L_INT LBitmap::Keystone(pPoints, pOutBitmap)

Performs inverse perspective transformation (keystoning) on an image.


L_POINT* pPoints

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


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


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


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


Win32, x64.

See Also


#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); 
    return nRet; 
Help Version 22.0.2022.4.4
Products | Support | Contact Us | Intellectual Property Notices
© 1991-2022 LEAD Technologies, Inc. All Rights Reserved.

LEADTOOLS Raster Imaging C++ Class Library Help