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Course IPCis: Image Processing with C#
Chapter C2: The Complete Code of the Histogram Project
Copyright © by V. Miszalok, last update: 09-05-2010 |
Copy all this code into an empty Form1.cs of a new Windows Application C#-project histo1 and clear Form1.Designer.cs and Program.cs.
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Windows.Forms;
public class Form1 : Form
{ [STAThread] static void Main() { Application.Run( new Form1() ); }
Brush bbrush = SystemBrushes.ControlText;
Brush wbrush = new SolidBrush( Color.White );
Pen bpen = SystemPens.ControlText;
Pen rpen = new Pen( Color.Red );
Bitmap bmp, bmp_binary, bmp_histo;
BitmapData binaryData; //for Versions 2 and 3
Byte[,] grayarray; //2D-Byte-Array
Int32[] Histogram = new Int32[256];
Rectangle histo_r = new Rectangle( 0,0,257,101 );
Graphics g, g_histo;
Byte[] ORmask = { 128, 64, 32, 16, 8, 4, 2, 1 };// 1 bit each //for Version 3
Byte[] ANDmask = { 127, 191, 223, 239, 247, 251, 253, 254 };// 7 bits each //for Version 3
public Form1()
{ MenuItem miRead = new MenuItem( "&Read", new EventHandler( MenuFileRead ) );
MenuItem miExit = new MenuItem( "&Exit", new EventHandler( MenuFileExit ) );
MenuItem miFile = new MenuItem( "&File", new MenuItem[] { miRead, miExit } );
Menu = new System.Windows.Forms.MainMenu( new MenuItem[] { miFile } );
Text = "Histo1";
SetStyle( ControlStyles.ResizeRedraw, true );
Width = 800;
Height = 600;
}
private void MenuFileRead( object obj, EventArgs ea )
{ OpenFileDialog dlg = new OpenFileDialog();
if ( dlg.ShowDialog() != DialogResult.OK ) return;
try
{ Cursor.Current = Cursors.WaitCursor;
bmp = (Bitmap)Image.FromFile( dlg.FileName );
GenerateTheHistogram();
Cursor.Current = Cursors.Arrow;
Invalidate();
} catch {}
}
private void GenerateTheHistogram()
{ if ( bmp == null ) return;
//bmp_binary = new Bitmap( bmp.Width, bmp.Height, PixelFormat.Format32bppRgb ); //Version 1
//bmp_binary = new Bitmap( bmp.Width, bmp.Height, PixelFormat.Format32bppRgb ); //Version 2
bmp_binary = new Bitmap( bmp.Width, bmp.Height, PixelFormat.Format1bppIndexed ); //Version 3
grayarray = new Byte[bmp.Height, bmp.Width];
Color color;
for ( Int32 y=0; y < bmp.Height; y++ )
for ( Int32 x=0; x < bmp.Width; x++ )
{ color = bmp.GetPixel( x, y );
Int32 gray = ( color.R + color.G + color.B ) / 3;
grayarray[y, x] = (Byte)gray;
Histogram[gray]++;
}
Int32 hmax = 0;
for ( Int32 i=0; i < 256; i++ )
if ( Histogram[i] > hmax ) hmax = Histogram[i];
for ( Int32 i=0; i < 256; i++ )
Histogram[i] = (100*Histogram[i]) / hmax;
bmp_histo = new Bitmap( histo_r.Width, histo_r.Height, PixelFormat.Format32bppRgb );
g_histo = Graphics.FromImage( bmp_histo );
g_histo.FillRectangle( wbrush, 0,0,256,100 );
g_histo.DrawString( "click here and move !", Font, bbrush, 1, 1 );
for ( Int32 i=0; i < 256; i++ ) g_histo.DrawLine( bpen, i, 100, i, 100 - Histogram[i] );
g_histo.DrawRectangle( rpen, 0,0,256,100 );
}
private void MenuFileExit( object obj, EventArgs ea )
{ Application.Exit(); }
protected override void OnMouseMove( MouseEventArgs e )
{ if ( e.Button == MouseButtons.None ) return;
if ( !histo_r.Contains( e.X, e.Y ) ) return;
if ( bmp == null ) return;
Byte threshold = (Byte)(e.X - histo_r.X);
/*
//Version 1 (no pointers but slow)***************************************
for ( Int32 y=0; y < bmp.Height; y++ )
for ( Int32 x=0; x < bmp.Width; x++ )
{ if ( grayarray[y ,x] > threshold )
bmp_binary.SetPixel( x, y, Color.White );
else bmp_binary.SetPixel( x, y, Color.Black );
}
//End of Version 1 ******************************************************
*/
/*
//Version 2 (fast pointers creating a memory wasting 32-bit binary image)*
unsafe
{ //lock bmp_binary from being shifted in memory by the garbage collector
binaryData = bmp_binary.LockBits( new Rectangle( 0,0,bmp.Width,bmp.Height ),
ImageLockMode.WriteOnly, PixelFormat.Format32bppRgb );
//Byte* p1fix, p1run = fixed + running pointers to grayarray = input image
UInt32* p2fix, p2run; //fixed + running pointers to binaryData = output image
fixed ( Byte* p1fix = grayarray ) // lock grayarray in memory
{ Byte* p1run = p1fix; // running pointer to grayarray
p2fix = (UInt32*)binaryData.Scan0; // pointer to output image
for ( int y=0; y < bmp.Height; y++ )
{ p2run = p2fix + y * bmp.Width; //p2run points to first byte in row y
for ( int x=0; x < bmp.Width; x++ )
{ if ( *p1run++ > threshold ) *p2run++ = 0xFFFFFF; // white
else *p2run++ = 0; // black
} // end of for x
} // end of for y
} // end of fixed, end of p1fix, unlock grayarray
bmp_binary.UnlockBits( binaryData ); //end of p2fix, unlock bmp_binary
} // end of unsafe
//End of Version 2 ******************************************************
*/
//Version 3 (fast pointers creating a 1-bit binary image)****************
unsafe
{ //lock bmp_binary from being shifted in memory by the garbage collector
binaryData = bmp_binary.LockBits( new Rectangle( 0,0,bmp.Width,bmp.Height ),
ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed );
Byte* p2fix, p2row, p2run; // pointers to binaryData = output image
fixed ( Byte* p1fix = grayarray ) // lock grayarray = input image in memory
{ Byte* p1run = p1fix; // running pointer to grayarray
p2fix = (byte*)binaryData.Scan0; // pointer to output image
for ( int y=0; y < bmp.Height; y++ )
{ p2row = p2fix + y * binaryData.Stride; //p2row points to first byte in row y
for ( int x=0; x < bmp.Width; x++ )
{ p2run = p2row + x / 8;
if ( *p1run++ > threshold ) *p2run |= ORmask[ x % 8 ];//set 1 bit
else *p2run &= ANDmask[ x % 8 ];//remove 1 bit
} // end of for x
} // end of for y
} // end of fixed, end of p1fix, unlock grayarray
bmp_binary.UnlockBits( binaryData ); // end of p2fix, unlock bmp_binary
} // end of unsafe
//End of Version 3 ******************************************************
g = CreateGraphics();
g.DrawImage( bmp_binary, ClientRectangle );
g.DrawImage( bmp_histo, histo_r );
g.DrawLine( rpen, histo_r.X+threshold, histo_r.Y,
histo_r.X+threshold, histo_r.Y+histo_r.Height-1 );
}
protected override void OnMouseUp(MouseEventArgs e)
{ Invalidate(); }
protected override void OnPaint( PaintEventArgs e )
{ if ( bmp == null )
{ e.Graphics.DrawString( "Open an Image File !", Font, bbrush, 0, 0 ); return; }
e.Graphics.DrawImage( bmp, ClientRectangle );
histo_r.X = ClientRectangle.Width - histo_r.Width - 10;
histo_r.Y = ClientRectangle.Height - histo_r.Height - 10;
e.Graphics.DrawImage( bmp_histo, histo_r );
}
}
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