Image processing functions

Reverse Phase
Public static bool invert (Bitmap B)
{
Bitmapdata bmdata = B. lockbits (New rectangle (0, 0, B. Width, B. Height ),
Imagelockmode. readwrite, pixelformat. format24bpprgb );
Int stride = bmdata. stride;
System. intptr scan0 = bmdata. scan0;
Unsafe
{
Byte * P = (byte *) (void *) scan0;
Int noffset = stride-B. Width * 3;
Int nwidth = B. Width * 3;
For (INT y = 0; y <B. height; ++ y)
{
For (INT x = 0; x <nwidth; ++ x screen. width/2) This. width = screen. width/2 "vspace = 2 border = 0>
{
P [0] = (byte) (255-p [0]);
++ P;
}
P + = noffset;
}
}

B. unlockbits (bmdata );
Return true;
}

Public static bool grayscale (Bitmap B)
{
// Black/white
Bitmapdata bmdata = B. lockbits (New rectangle (0, 0, B. Width, B. Height ),
Imagelockmode. readwrite, pixelformat. format24bpprgb );
Int stride = bmdata. stride;
System. intptr scan0 = bmdata. scan0;
Unsafe
{
Byte * P = (byte *) (void *) scan0;
Int noffset = stride-B. Width * 3;
Byte red, green, blue;
For (INT y = 0; y <B. height; ++ y)
{
For (INT x = 0; x <B. width; ++ x screen. width/2) This. width = screen. width/2 "vspace = 2 border = 0>
{
Blue = P [0];
Green = P [1];
Red = P [2];
P [0] = P [1] = P [2] = (byte) (. 299 * red
+. 587 * green
+. 114 * Blue );
P + = 3;
}
P + = noffset;
}
}
B. unlockbits (bmdata );
Return true;
}

Brightness
Public static bool brightness (Bitmap B, int nbrightness)
{
Bitmapdata bmdata = B. lockbits (New rectangle (0, 0, B. Width, B. Height ),
Imagelockmode. readwrite, pixelformat. format24bpprgb );
Int stride = bmdata. stride;
System. intptr scan0 = bmdata. scan0;
Unsafe
{
Byte * P = (byte *) (void *) scan0;
Int noffset = stride-B. Width * 3;
Int nwidth = B. Width * 3;
For (INT y = 0; y <B. height; ++ y)
{
For (INT x = 0; x <nwidth; ++ X)
{
Int nval = (INT) (p [0] + nbrightness );
If (nval <0) nval = 0;
If (nval> 255) nval = 255;
P [0] = (byte) nval;
++ P;
}
P + = noffset;
}
}
B. unlockbits (bmdata );
Return true;
}

Contrast
Public static bool contrast (Bitmap B, int ncontrast)
{
If (ncontrast <-100) return false;
If (ncontrast> 100) return false;
Double pixel = 0, contrast = (100.0 + ncontrast)/100.0;
Contrast * = contrast;
Bitmapdata bmdata = B. lockbits (New rectangle (0, 0, B. Width, B. Height ),
Imagelockmode. readwrite, pixelformat. format24bpprgb );
Int stride = bmdata. stride;
System. intptr scan0 = bmdata. scan0;
Unsafe
{
Byte * P = (byte *) (void *) scan0;
Int noffset = stride-B. Width * 3;
Int nwidth = B. Width * 3;
For (INT y = 0; y <B. height; ++ y)
{
For (INT x = 0; x <nwidth; ++ X)
{
Byte color = P [0];
Pixel = color/255.0;
Pixel-= 0.5;
Pixel * = contrast;
Pixel + = 0.5;
Pixel * = 255;
If (pixel <0) pixel = 0;
If (pixel> 255) pixel = 255;
P [0] = (byte) pixel;
++ P;
}
P + = noffset;
}
}
B. unlockbits (bmdata );
Return true;
}

Public static bool gamma (Bitmap B)
{
Bitmapdata bmdata = B. lockbits (New rectangle (0, 0, B. Width, B. Height ),
Imagelockmode. readwrite, pixelformat. format24bpprgb );
Int stride = bmdata. stride;
System. intptr scan0 = bmdata. scan0;

Byte [] redgamma = new byte [1, 256];
Byte [] greengamma = new byte [256];
Byte [] bluegamma = new byte [1, 256];

For (INT I = 0; I <256; ++ I)
{
Redgamma [I] = (byte) math. Min (255, (INT) (255.0
* Math. Pow (I/255.0, 1.0/5) + 0.5); // 5 of 1.0/5 is the red GAMMA value.
Greengamma [I] = (byte) math. Min (255, (INT) (255.0
* Math. Pow (I/255.0, 1.0/5) + 0.5 ));
Bluegamma [I] = (byte) math. Min (255, (INT) (255.0
* Math. Pow (I/255.0, 1.0/5) + 0.5 ));
}

Unsafe
{
Byte * P = (byte *) (void *) scan0;
Int noffset = stride-B. Width * 3;
Int nwidth = B. Width * 3;

Byte red, green, blue;
For (INT y = 0; y <B. height; ++ y)
{
For (INT x = 0; x <B. width; ++ X)
{
Blue = P [0];
Green = P [1];
Red = P [2];

P [0] = (byte) bluegamma [(INT) BLue];
P [1] = (byte) greengamma [(INT) Green];
P [2] = (byte) redgamma [(INT) Red];
P + = 3;
}
P + = noffset;
}
}

B. unlockbits (bmdata );
Return true;
}

Channel
Public static bool channel (Bitmap B, char RGB)
{
Bitmapdata bmdata = B. lockbits (New rectangle (0, 0, B. Width, B. Height ),
Imagelockmode. readwrite, pixelformat. format24bpprgb );
Int stride = bmdata. stride;
System. intptr scan0 = bmdata. scan0;

Unsafe
{
Byte * P = (byte *) (void *) scan0;
Int noffset = stride-B. Width * 3;
Int nwidth = B. Width * 3;

Byte red, green, blue;
For (INT y = 0; y <B. height; ++ y)
{
For (INT x = 0; x <B. width; ++ X)
{
Switch (RGB)
{
Case 'r ':
P [0] = (byte) 0;
P [1] = (byte) 0;
Break;
Case 'G ':
P [0] = (byte) 0;
P [2] = (byte) 0;
Break;
Case 'B ':
P [2] = (byte) 0;
P [1] = (byte) 0;
Break;
}
P + = 3;
}
P + = noffset;
}
}

B. unlockbits (bmdata );

Return true;
}