Histogram

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Windows.Forms;


namespace Histogram
{
/// <summary>
/// Summary description for LogicalOperator.
/// </summary>
public class Operator
{
private Bitmap bmpimg;
public Operator()
{
//
// TODO: Add constructor logic here
//
}

public void setImage( Bitmap bmp )
{
bmpimg = ( Bitmap )bmp.Clone( );
}

public Bitmap getImage( )
{
return ( Bitmap )bmpimg.Clone( );
}

public void calcHisto( Form1 form )
{
BitmapData data = bmpimg.LockBits( new System.Drawing.Rectangle( 0 , 0 , bmpimg.Width , bmpimg.Height ), ImageLockMode.ReadWrite , PixelFormat.Format24bppRgb );

unsafe
{
byte* ptr = ( byte* )data.Scan0;

int remain = data.Stride - data.Width * 3;

int[ ] histogram = new int[ 256 ];
for( int i = 0 ; i < histogram.Length ; i ++ )
histogram[ i ] = 0;

for( int i = 0 ; i < data.Height ; i ++ )
{
for( int j = 0 ; j < data.Width ; j ++ )
{
int mean = ptr[ 0 ] + ptr[ 1 ] + ptr[ 2 ];
mean /= 3;

histogram[ mean ] ++;
ptr += 3;
}

ptr += remain;
}

drawHistogram( histogram , form );

}

bmpimg.UnlockBits( data ); 
}


public void drawHistogram( int[ ] histogram , Form1 form )
{

Bitmap bmp = new Bitmap( histogram.Length + 10 , 310 );
form.pictureBox2.Image = bmp;
int keep = 0;

BitmapData data = bmp.LockBits( new System.Drawing.Rectangle( 0 , 0 , bmp.Width , bmp.Height ), ImageLockMode.ReadWrite , PixelFormat.Format24bppRgb );

unsafe
{
int remain = data.Stride - data.Width * 3;
byte* ptr = ( byte* )data.Scan0;

for( int i = 0 ; i < data.Height ; i ++ )
{

for( int j = 0 ; j < data.Width ; j ++ )
{
ptr[ 0 ] = ptr[ 1 ] = ptr[ 2 ] = 150;
ptr += 3;
}
ptr += remain;

}

int max = 0;
for( int i = 0 ; i < histogram.Length ; i ++ )
{

if( max < histogram[ i ] )
max = histogram[ i ];

}

for( int i = 0 ; i < histogram.Length ; i ++ )
{
ptr = ( byte* )data.Scan0;
ptr += data.Stride * ( 305 ) + ( i + 5 ) * 3;

int length = ( int )( 1.0 * histogram[ i ] * 300 / max );

for( int j = 0 ; j < length ; j ++ )
{
ptr[ 0 ] = 255;
ptr[ 1 ] = ptr[ 2 ] = 0;
ptr -= data.Stride;
}

}

}

bmp.UnlockBits( data );    
}

}
}