/// <summary>
/// Convert from RGB to LAB color space.
/// </summary>
///
/// <param name="rgb">Source color in <b>RGB</b> color space.</param>
///
/// <returns>Returns <see cref="LAB"/> instance, which represents converted color value.</returns>
///
public static LAB FromRGB(RGB rgb)
{
LAB hsl = new LAB();
FromRGB(rgb, hsl);
return(hsl);
}
/// <summary>
/// Convert from LAB to RGB color space.
/// </summary>
///
/// <param name="hsl">Source color in <b>LAB</b> color space.</param>
/// <param name="rgb">Destination color in <b>RGB</b> color space.</param>
///
public static void ToRGB(LAB lab, RGB rgb)
{
rgb.Red = (byte)(lab.Lightness + lab.A / 2.0 + lab.B / 3.0);
rgb.Green = (byte)(lab.Lightness - lab.A / 2.0 + lab.B / 3.0);
rgb.Blue = (byte)(lab.Lightness - (2.0 * lab.B / 3.0));
}
/// <summary>
/// Selection based on pixel similarity in LAB color space
/// </summary>
public static unsafe Bitmap Similiar_LAB(Bitmap image, Rectangle rect, List <LAB> labs, int similarity)
{
Bitmap dest = (Bitmap)image.Clone();
if (labs.Count == 0)
{
return(dest);
}
BitmapData srcDat = image.LockBits(rect, ImageLockMode.ReadOnly, image.PixelFormat);
BitmapData dstDat = dest.LockBits(rect, ImageLockMode.ReadWrite, dest.PixelFormat);
int width = rect.Width;
int height = rect.Height;
int stride = srcDat.Stride;
// get pixel size
int pixelSize = (image.PixelFormat == PixelFormat.Format24bppRgb) ? 3 : 4;
int offset = stride - width * pixelSize;
// do the job
byte *src = (byte *)srcDat.Scan0.ToPointer();
byte *dst = (byte *)dstDat.Scan0.ToPointer();
//L = 0～255
//A = -255～255 = 0～511
//B = -255～255 = 0～511
const int LAB_num = 256 + 512 + 512;
int[] table_mix = new int[LAB_num];
for (int i = 0; i < LAB_num; i++)
{
table_mix[i] = -1;
}
int total_l;
foreach (LAB lab in labs)
{
total_l = (int)(lab.Lightness + lab.A + lab.B + 510);
for (int i = 0; i < similarity / 2; i++)
{
if ((total_l + i) < LAB_num)
{
table_mix[total_l + i] = 1;
}
if ((total_l - i) >= 0)
{
table_mix[total_l - i] = 1;
}
}
}
int koba;
// for each row
for (int y = 0; y < height; y++)
{
// for each pixel
for (int x = 0; x < width; x++, src += pixelSize, dst += pixelSize)
{
LAB lab = LAB.FromRGB(new RGB(src[RGB.R], src[RGB.G], src[RGB.B]));
koba = (int)(lab.Lightness + lab.A + lab.B + 510);
if (table_mix[koba] == 1)
{
dst[RGB.R] = dst[RGB.G] = dst[RGB.B] = 0;
}
else
{
dst[RGB.R] = dst[RGB.G] = dst[RGB.B] = 255;
}
}
src += offset;
dst += offset;
}
image.UnlockBits(srcDat);
dest.UnlockBits(dstDat);
return(dest);
}
/// <summary>
/// Convert from RGB to LAB color space.
/// </summary>
public static void FromRGB(RGB rgb, LAB lab)
{
lab.Lightness = (rgb.Red + rgb.Green + rgb.Blue) / 3;
lab.A = rgb.Red - rgb.Green;
lab.B = (rgb.Red + rgb.Green) / 2 - rgb.Blue;
}
/// <summary>
/// Selection based on pixel similarity in LAB color space
/// </summary>
public static unsafe Bitmap Similiar_LABAver(Bitmap image, Rectangle rect, List <LAB> labs, int similarity)
{
Bitmap dest = (Bitmap)image.Clone();
if (labs.Count == 0)
{
return(dest);
}
BitmapData srcDat = image.LockBits(rect, ImageLockMode.ReadOnly, image.PixelFormat);
BitmapData dstDat = dest.LockBits(rect, ImageLockMode.ReadWrite, dest.PixelFormat);
int width = rect.Width;
int height = rect.Height;
int stride = srcDat.Stride;
// get pixel size
int pixelSize = (image.PixelFormat == PixelFormat.Format24bppRgb) ? 3 : 4;
int offset = stride - width * pixelSize;
// do the job
byte *src = (byte *)srcDat.Scan0.ToPointer();
byte *dst = (byte *)dstDat.Scan0.ToPointer();
//L = 0～255
//A = -255～255
//B = -255～255
int sumL, sumA, sumB;
int averL, averA, averB;
int minL, minA, minB;
int maxL, maxA, maxB;
sumL = sumA = sumB = 0;
foreach (LAB lab in labs)
{
sumL += lab.Lightness;
sumA += lab.A;
sumB += lab.B;
}
averL = sumL / labs.Count;
averA = sumA / labs.Count;
averB = sumB / labs.Count;
minL = Math.Max(averL - similarity / 2, 0);
minA = Math.Max(averA - similarity / 2, -255);
minB = Math.Max(averB - similarity / 2, -255);
maxL = Math.Min(averL + similarity / 2, 255);
maxA = Math.Min(averA + similarity / 2, 255);
maxB = Math.Min(averB + similarity / 2, 255);
// for each row
for (int y = 0; y < height; y++)
{
// for each pixel
for (int x = 0; x < width; x++, src += pixelSize, dst += pixelSize)
{
LAB lab = LAB.FromRGB(new RGB(src[RGB.R], src[RGB.G], src[RGB.B]));
if (lab.Lightness >= minL && lab.Lightness <= maxL &&
lab.A >= minA && lab.A <= maxA &&
lab.B >= minB && lab.B <= maxB)
{
dst[RGB.R] = dst[RGB.G] = dst[RGB.B] = 0;
}
else
{
dst[RGB.R] = dst[RGB.G] = dst[RGB.B] = 255;
}
}
src += offset;
dst += offset;
}
image.UnlockBits(srcDat);
dest.UnlockBits(dstDat);
return(dest);
}
