/// <summary>
/// Sets Contrast of image using lockbits.
/// Note that the threshold should be a value between -100 and 100.
/// </summary>
/// <param name="bmp"> Source of the bitmap to be modified and returned. </param>
/// <param name="threshold"> Values between -100 and 100, with 0 being the unmodified one.</param>
/// <returns> A new bitmap with the specified contrast level. </returns>
public static Bitmap SetContrast(Bitmap bmp, int threshold)
{
var modifiedContrast = new Bitmap(bmp);
var lockedBitmap = new LockBitmap(modifiedContrast);
lockedBitmap.LockBits();
var contrast = Math.Pow((100.0 + threshold) / 100.0, 2);
for (int y = 0; y < lockedBitmap.Height; y++)
{
for (int x = 0; x < lockedBitmap.Width; x++)
{
var oldColor = lockedBitmap.GetPixel(x, y);
var red = ((((oldColor.R / 255.0) - 0.5) * contrast) + 0.5) * 255.0;
var green = ((((oldColor.G / 255.0) - 0.5) * contrast) + 0.5) * 255.0;
var blue = ((((oldColor.B / 255.0) - 0.5) * contrast) + 0.5) * 255.0;
if (red > 255)
{
red = 255;
}
if (red < 0)
{
red = 0;
}
if (green > 255)
{
green = 255;
}
if (green < 0)
{
green = 0;
}
if (blue > 255)
{
blue = 255;
}
if (blue < 0)
{
blue = 0;
}
var newColor = Color.FromArgb(oldColor.A, (int)red, (int)green, (int)blue);
lockedBitmap.SetPixel(x, y, newColor);
}
}
lockedBitmap.UnlockBits();
return(modifiedContrast);
}
/// <summary>
/// Grayscales an image using lockbits.
/// </summary>
/// <param name="bmp"> Source of the bitmap to be resized and returned. </param>
/// <returns> A new grayscaled bitmap. </returns>
public static Bitmap Grayscale(Bitmap bmp)
{
var grayScaled = new Bitmap(bmp);
var lockedBitmap = new LockBitmap(grayScaled);
lockedBitmap.LockBits();
for (var y = 0; y < lockedBitmap.Height; y++)
{
for (var x = 0; x < lockedBitmap.Width; x++)
{
var color = lockedBitmap.GetPixel(x, y);
var hsp = (int)RGBToHSP(color);
lockedBitmap.SetPixel(x, y, Color.FromArgb(hsp, hsp, hsp));
}
}
lockedBitmap.UnlockBits();
return(grayScaled);
}