private ReturnValues posterise_5level_custom2(int[] notused)
{
// First row = Input
// Second row = Output
// e.g. Between 0 and 24, output 0
// Between 25 and 49, output 38
// Between 50 and 99, output 75
// etc.
string a = @"
0 75 150 200 228 255
0 113 175 214 255
";
var data = ParseString(a);
var rv = new ReturnValues();
int pos = 0;
for (int i = 0; i < 256; i++)
{
if ((pos < data.Length - 1) && // avoid array out-of-bounds
(i == data[pos + 1].InValue)) // check next value
{
pos++;
}
rv.AssignValue(i, data[pos].OutValue);
}
return(rv);
}
//private void linear()
//{
// foreach (var array in new[] { _transformR, _transformG, _transformB })
// for (int i = 0; i < 256; i++)
// array[i] = i;
//}
//private void noise1()
//{
// for (int i = 0; i < 256; i++)
// foreach (var transform in new[] { _transformR, _transformG, _transformB })
// transform[i] = Clamp(i +
// (((i / 2) % 2 == 0) ? (int)slider1.Value : 0 - (int)slider1.Value));
//}
//private void noise2()
//{
// Random r = new Random();
// for (int i = 0; i < 256; i++)
// foreach (var transform in new[] { _transformR, _transformG, _transformB })
// transform[i] = Clamp(i + (0 - ((int)slider1.Value / 2)) + r.Next((int)slider1.Value));
//}
//private void noise3()
//{
// int step =(int)slider1.Value;
// for (int i = 0; i < 256; i++)
// foreach (var transform in new[] { _transformR, _transformG, _transformB })
// transform[i] = Clamp(i +
// (step - (i % step) - (i % step)));
//}
//private int Clamp(int val)
//{
// if (val < 0) return 0;
// if (val > 255) return 255;
// return val;
//}
//private void posterise1()
//{
// double posterise_multiplier = 255.0 / (int)slider1.Value;
// for (int i = 0; i < 256; i++)
// foreach (var transform in new[] { _transformR, _transformG, _transformB })
// transform[i] = (int)(Convert.ToInt32(i / posterise_multiplier) * posterise_multiplier);
//}
//private void posterise2()
//{
// int posterise_level = (int)slider1.Value;
// if (posterise_level <= 1)
// throw new Exception("Posterise level 1 or below not allowed");
// double multiplier = 255.0 / (posterise_level - 1.0);
// foreach (var transform in new[] { _transformR, _transformG, _transformB })
// {
// for (int i = 0; i < 256; i++)
// {
// int index = (int)Math.Floor(i * (posterise_level / 256.0));
// transform[i] = (int)Math.Round(index * multiplier);
// }
// }
//}
//private void posterise_3level_custom2()
//{
// int threshold1 = (int)slider1.Value;
// int threshold2 = (int)slider2.Value;
// int threshold3 = (int)slider3.Value;
// foreach (var transform in new[] { _transformR, _transformG, _transformB })
// {
// for (int i = 0; i < 256; i++)
// {
// if (transform == _transformG)
// // 3 bit
// transform[i] = i >= threshold2 ? 255
// : i >= threshold3 ? 170
// : i >= threshold1 ? 85
// : 0;
// else
// // 2 bit
// transform[i] = i >= threshold2 ? 255
// : i >= threshold1 ? 128
// : 0;
// }
// }
//}
private ReturnValues posterise_2level_custom(int[] sliderValues)
{
int threshold = sliderValues[0];
var rv = new ReturnValues();
for (int i = 0; i < 256; i++)
{
rv.AssignValue(i, i >= threshold ? 255 : 0);
}
return(rv);
}
private ReturnValues posterise_4level_custom(int[] sliderValues)
{
int threshold1 = sliderValues[0];
int threshold2 = sliderValues[1];
int threshold3 = sliderValues[2];
var rv = new ReturnValues();
for (int i = 0; i < 256; i++)
{
rv.AssignValue(i, i >= threshold3 ? 255
: i >= threshold2 ? 170
: i >= threshold1 ? 85
: 0);
}
return(rv);
}
private ReturnValues posterise_nlevels(int nlevels)
{
// Number of levels ^ 3 = Number of different colours
// e.g. 256 ^ 3 = 16,777,216 (24-bit, 8-bit per channel)
// e.g. 2 ^ 3 = 8 colours (red, yellow, green, cyan, blue, magenta, black, white)
int[] outvalues = new int[nlevels]; // e.g. [0,127,255]
float divisor = nlevels - 1;
for (int i = 0; i < nlevels; i++)
{
outvalues[i] = (int)((255 / divisor) * i);
}
int[] thresholds = new int[nlevels - 1]; // e.g. [85,170]
for (int i = 0; i < (nlevels - 1); i++)
{
thresholds[i] = (int)((255 / (float)nlevels) * (i + 1));
}
int Lookup(int v) // local function
{
for (int t = 0; t < thresholds.Length; t++)
{
if (v < thresholds[t])
{
return(outvalues[t]);
}
}
return(outvalues[thresholds.Length]);
}
var rv = new ReturnValues();
for (int i = 0; i < 256; i++)
{
rv.AssignValue(i, Lookup(i));
}
return(rv);
}