Complete image contrast enhancement code under opencv

// Enforce. cpp: defines the entry point for the console application.
//

# Include "stdafx. H"

# Include "cv. H"
# Include "highgui. H"
# Include
# Include
Int imagestretchbyhistogram (iplimage * SRC, iplimage * DST );

Int _ tmain (INT argc, _ tchar * argv [])
{
Iplimage * pimg;
Pimg = cvloadimage ("C: \ lena.jpg",-1 );

// Create a grayscale image
Iplimage * grayimage = cvcreateimage (cvgetsize (pimg), ipl_depth_8u, 1 );
Iplimage * dstgrayimage = cvcreateimage (cvgetsize (pimg), ipl_depth_8u, 1 );
Cvcvtcolor (pimg, grayimage, cv_bgr2gray );
Imagestretchbyhistogram (grayimage, dstgrayimage );

Cvnamedwindow ("dstgrayimage", 1); // create a window
Cvnamedwindow ("grayimage", 1); // create a window
Cvshowimage ("dstgrayimage", dstgrayimage); // display the image
Cvshowimage ("grayimage", grayimage); // display the image
Cvwaitkey (0); // wait for the key

Cvdestroywindow ("dstgrayimage"); // destroy the window
Cvdestroywindow ("grayimage"); // destroy the window
Cvreleaseimage (& pimg); // release the image
Cvreleaseimage (& grayimage); // release the image
Cvreleaseimage (& dstgrayimage); // release the image

Return 0;
}

Int imagestretchbyhistogram (iplimage * SRC, iplimage * DST)
/*************************************** **********
Function:
Description: due to the poor image quality of the camera, image enhancement is required based on the histogram,
Stretch the grayscale Domain value to 0-255.
Cballs:
Called:
Input: Single Channel grayscale image
Output: Single Channel grayscale images of the same size
Return:
Others: http://www.xiaozhou.net/ReadNews.asp? Newsid= 771
Date: 2007-1-5
**************************************** *********/
{
// P [] the appearance probability of each gray level of the image;
// P1 [] stores the probability and prior to each gray level for histogram transformation;
// Num [] Number of gray-level occurrences of the image;

Assert (SRC-> width = DST-> width );
Float P [1, 256], P1 [2, 256], num [2, 256];
// Clear three Arrays
Memset (p, 0, sizeof (p ));
Memset (P1, 0, sizeof (P1 ));
Memset (Num, 0, sizeof (Num ));

Int Height = Src-> height;
Int width = Src-> width;
Long wmulh = height * width;

// Find the number of times each gray level of the image appears
// To do use OpenMP
For (INT x = 0; X {
For (INT y = 0; y {
Uchar v = (uchar *) (SRC-> imagedata + Src-> widthstep * y) [x];
Num [v] ++;
}
}

// Calculate the appearance probability of each gray level of the stored image
For (INT I = 0; I <256; I ++)
{
P [I] = num [I]/wmulh;
}

// Calculate the probability and
For (INT I = 0; I <256; I ++)
{
For (int K = 0; k <= I; k ++)
P1 [I] + = P [k];
}

// Histogram Transformation
// To do use OpenMP
For (INT x = 0; X {
For (INT y = 0; y {
Uchar v = (uchar *) (SRC-> imagedata + Src-> widthstep * y) [x];
(Uchar *) (DST-> imagedata + DST-> widthstep * y) [x] = P1 [v] * 255 + 0.5;
}
}

Return 0;

}

The imagestretchbyhistogram function comes from:

Http://blog.csdn.net/hardVB/archive/2007/01/05/1474880.aspx

 

This article from the csdn blog, reproduced please indicate the source: http://blog.csdn.net/soarnic/archive/2008/09/26/2985116.aspx