/// <summary>
/// Calculate Gradient vector between the given pixel and its right and bottom ones
/// </summary>
/// <param name="x">pixel x-coordinate</param>
/// <param name="y">pixel y-coordinate</param>
/// <param name="ImageMatrix">colored image matrix</param>
/// <returns></returns>
private static Vector2D CalculateGradientAtPixel(int x, int y, RGBPixel[,] ImageMatrix)
{
Vector2D gradient = new Vector2D();
RGBPixel mainPixel = ImageMatrix[y, x];
double pixelGrayVal = 0.21 * mainPixel.red + 0.72 * mainPixel.green + 0.07 * mainPixel.blue;
if (y == GetHeight(ImageMatrix) - 1)
{
//boundary pixel.
gradient.Y = 0;
}
else
{
RGBPixel downPixel = ImageMatrix[y + 1, x];
double downPixelGrayVal = 0.21 * downPixel.red + 0.72 * downPixel.green + 0.07 * downPixel.blue;
gradient.Y = pixelGrayVal - downPixelGrayVal;
}
if (x == GetWidth(ImageMatrix) - 1)
{
//boundary pixel.
gradient.X = 0;
}
else
{
RGBPixel rightPixel = ImageMatrix[y, x + 1];
double rightPixelGrayVal = 0.21 * rightPixel.red + 0.72 * rightPixel.green + 0.07 * rightPixel.blue;
gradient.X = pixelGrayVal - rightPixelGrayVal;
}
return(gradient);
}
/// <summary>
/// Open an image and load it into 2D array of colors (size: Height x Width)
/// </summary>
/// <param name="ImagePath">Image file path</param>
/// <returns>2D array of colors</returns>
public static RGBPixel[,] OpenImage(string ImagePath)
{
Bitmap original_bm = new Bitmap(ImagePath);
int Height = original_bm.Height;
int Width = original_bm.Width;
RGBPixel[,] Buffer = new RGBPixel[Height, Width];
unsafe
{
BitmapData bmd = original_bm.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, original_bm.PixelFormat);
int x, y;
int nWidth = 0;
bool Format32 = false;
bool Format24 = false;
bool Format8 = false;
if (original_bm.PixelFormat == PixelFormat.Format24bppRgb)
{
Format24 = true;
nWidth = Width * 3;
}
else if (original_bm.PixelFormat == PixelFormat.Format32bppArgb || original_bm.PixelFormat == PixelFormat.Format32bppRgb || original_bm.PixelFormat == PixelFormat.Format32bppPArgb)
{
Format32 = true;
nWidth = Width * 4;
}
else if (original_bm.PixelFormat == PixelFormat.Format8bppIndexed)
{
Format8 = true;
nWidth = Width;
}
int nOffset = bmd.Stride - nWidth;
byte *p = (byte *)bmd.Scan0;
for (y = 0; y < Height; y++)
{
for (x = 0; x < Width; x++)
{
if (Format8)
{
Buffer[y, x].red = Buffer[y, x].green = Buffer[y, x].blue = p[0];
p++;
}
else
{
Buffer[y, x].red = p[0];
Buffer[y, x].green = p[1];
Buffer[y, x].blue = p[2];
if (Format24)
{
p += 3;
}
else if (Format32)
{
p += 4;
}
}
}
p += nOffset;
}
original_bm.UnlockBits(bmd);
}
return(Buffer);
}
