// convert RGB TO HSI
private HSI RGB_2_HSI(int width, int height, byte[] RData, byte[] GData, byte[] BData)
{
// declare
HSI hsiImage = new HSI();
int pixels = width * height;
hsiImage.HData = new double[pixels];
hsiImage.SData = new double[pixels];
hsiImage.IData = new double[pixels];
// calculate HSI
for (int i = 0; i < height; ++i)
{
for (int j = 0; j < width; ++j)
{
int pos = i * width + j;
double R = RData[pos];
double G = GData[pos];
double B = BData[pos];
double theta = Math.Acos(0.5 * (R + R - G - B) /
Math.Sqrt((R - G) * (R - G) + (R - B) * (G - B)));
theta *= 180 / Math.PI;
if (GData[pos] < BData[pos])
{
theta = 360 - theta;
}
hsiImage.HData[pos] = theta;
hsiImage.SData[pos] = 1.0 - 3.0 * Math.Min(R, Math.Min(G, B)) / (R + G + B);
hsiImage.IData[pos] = (R + G + B) / 3.0;
}
}
return(hsiImage);
}
// show HSI image
private void button9_Click(object sender, EventArgs e)
{
if (pictureBox1.Image == null)
{
return;
}
HSI hsiImage = RGB_2_HSI(img.Width, img.Height, RData, GData, BData);
RGB rgbImage = HSI_2_RGB(img.Width, img.Height, hsiImage);
}
// convert HSI TO RGB
private RGB HSI_2_RGB(int width, int height, HSI hsiImage)
{
// declare
RGB rgbImage = new RGB();
int pixels = width * height;
rgbImage.RData = new byte[pixels];
rgbImage.GData = new byte[pixels];
rgbImage.BData = new byte[pixels];
// calculate RGB
for (int i = 0; i < height; ++i)
{
for (int j = 0; j < width; ++j)
{
int pos = i * width + j;
int H = (int)hsiImage.HData[pos];
double S = hsiImage.SData[pos];
double I = hsiImage.IData[pos];
if (H >= 0 && H < 120)
{
rgbImage.BData[pos] = (byte)(I * (1 - S));
rgbImage.RData[pos] = (byte)(I * (1 + S * Math.Cos(H * Math.PI / 180.0) / Math.Cos((60 - H) * Math.PI / 180.0)));
rgbImage.GData[pos] = (byte)(3 * I - rgbImage.BData[pos] - rgbImage.RData[pos]);
}
else if (H >= 120 && H < 240)
{
H -= 120;
rgbImage.RData[pos] = (byte)(I * (1 - S));
rgbImage.GData[pos] = (byte)(I * (1 + S * Math.Cos(H * Math.PI / 180.0) / Math.Cos((60 - H) * Math.PI / 180.0)));
rgbImage.BData[pos] = (byte)(3 * I - rgbImage.GData[pos] - rgbImage.RData[pos]);
}
else
{
H -= 240;
rgbImage.GData[pos] = (byte)(I * (1 - S));
rgbImage.BData[pos] = (byte)(I * (1 + S * Math.Cos(H * Math.PI / 180) / Math.Cos((60 - H) * Math.PI / 180)));
rgbImage.RData[pos] = (byte)(3 * I - rgbImage.GData[pos] - rgbImage.BData[pos]);
}
}
}
BuildBitmap(img.Width, img.Height, rgbImage.RData, rgbImage.GData, rgbImage.BData);
return(rgbImage);
}
// histogram equalization on I channel
private void button10_Click(object sender, EventArgs e)
{
if (pictureBox1.Image == null)
{
return;
}
// calculate hsi image;
HSI hsiImage = RGB_2_HSI(img.Width, img.Height, RData, GData, BData);
// convert i channel to byte
byte[] IData = new byte[img.Width * img.Height];
for (int i = 0; i < img.Width * img.Height; ++i)
{
IData[i] = (byte)hsiImage.IData[i];
}
// I channel histogram
int[] IHisto = Cal_Hist(IData);
int[] histoChange = Equalize_Hist(img.Width, img.Height, IHisto);
HSI_Histo_Equal(img.Width, img.Height, histoChange, IData, hsiImage);
}
// show HSI histogram on I channel
private void button12_Click(object sender, EventArgs e)
{
if (pictureBox1.Image == null)
{
return;
}
// calculate hsi image;
HSI hsiImage = RGB_2_HSI(img.Width, img.Height, RData, GData, BData);
// convert i channel to byte
byte[] IData = new byte[img.Width * img.Height];
for (int i = 0; i < img.Width * img.Height; ++i)
{
IData[i] = (byte)hsiImage.IData[i];
}
// I channel histogram
int[] IHisto = Cal_Hist(IData);
Form2 Iform2 = new Form2(IHisto, "I");
Iform2.Show();
}
// HSI histogram equalization post-operation
private void HSI_Histo_Equal(int width, int height, int[] histoChange, byte[] IData, HSI hsiImage)
{
// pixels of the image
int pixels = width * height;
// change the original image;
for (int i = 0; i < height; ++i)
{
for (int j = 0; j < width; ++j)
{
hsiImage.IData[i * width + j] = histoChange[IData[i * width + j]];
}
}
HSI_2_RGB(width, height, hsiImage);
}