public static Bitmap DarkerImage(Bitmap source, int val) =>
source.LinearFilter(input => {
var red = Max(0, input.R - val);
var green = Max(0, input.G - val);
var blue = Max(0, input.B - val);
return Color.FromArgb(red, green, blue);
});
public static Bitmap BrighterImage(Bitmap source, int val) =>
source.LinearFilter(input => {
var red = Min(255, input.R + val);
var green = Min(255, input.G + val);
var blue = Min(255, input.B + val);
return Color.FromArgb(red, green, blue);
});
public static Bitmap Invert(Bitmap source) =>
source.LinearFilter(input => {
var red = 255 - input.R;
var green = 255 - input.G;
var blue = 255 - input.B;
return Color.FromArgb(red, green, blue);
});
public static Bitmap SepiaTone(Bitmap source) =>
source.LinearFilter(input => {
var red = (int)(input.R * 0.462);
var green = (int)(input.G * 0.193);
var blue = (int)(input.B * 0.1083);
return Color.FromArgb(red, green, blue);
});
// the linear filters are just functions f: Color -> Color to process every pixel in parallel
public static Bitmap GrayScale(Bitmap source) =>
source.LinearFilter(input => {
var avg = (input.R + input.G + input.B)/3;
return Color.FromArgb(avg, avg, avg);
});