Travel through pixels in BMP
When you want to doing image processing on huge images GetPixel() method takes long time but I think my algorithm takes less time than other answers , for example you can test this code on 800 * 600 pixels image.
Bitmap bmp = new Bitmap("SomeImage");
// Lock the bitmap's bits.
Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
BitmapData bmpData = bmp.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
// Get the address of the first line.
IntPtr ptr = bmpData.Scan0;
// Declare an array to hold the bytes of the bitmap.
int bytes = bmpData.Stride * bmp.Height;
byte[] rgbValues = new byte[bytes];
byte[] r = new byte[bytes / 3];
byte[] g = new byte[bytes / 3];
byte[] b = new byte[bytes / 3];
// Copy the RGB values into the array.
Marshal.Copy(ptr, rgbValues, 0, bytes);
int count = 0;
int stride = bmpData.Stride;
for (int column = 0; column < bmpData.Height; column++)
{
for (int row = 0; row < bmpData.Width; row++)
{
b[count] = (byte)(rgbValues[(column * stride) + (row * 3)]);
g[count] = (byte)(rgbValues[(column * stride) + (row * 3) + 1]);
r[count++] = (byte)(rgbValues[(column * stride) + (row * 3) + 2]);
}
}
if you want to traverse it right, left, right, ... in one loop, this would do it:
for (int i = 0 ; i < bmp.Height * bmp.Width; ++i) {
int row = i / bmp.Height;
int col = i % bmp.Width;
if (row%2 != 0) col = bmp.Width - col-1;
var pixel = bmp.GetPixel(col, row);
}