Grid Pixelate

The algorithm processes an image creating the effect of an image with larger pixels.

   

• C#
• VB.Net

									public static void ApplyGridPixelate(ref Bitmap bmp, Size squareSize)
{
	Bitmap TempBmp = (Bitmap)bmp.Clone();

	BitmapData bmpData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
	BitmapData TempBmpData = TempBmp.LockBits(new Rectangle(0, 0, TempBmp.Width, TempBmp.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);

	unsafe
	{
		byte* ptr = (byte*)bmpData.Scan0.ToPointer();
		byte* TempPtr = (byte*)TempBmpData.Scan0.ToPointer();

		int stopAddress = (int)ptr + bmpData.Stride * bmpData.Height;

		int Val = 0;
		int i = 0, X = 0, Y = 0;
		int BmpStride = bmpData.Stride;
		int BmpWidth = bmp.Width;
		int BmpHeight = bmp.Height;
		int SqrWidth = squareSize.Width;
		int SqrHeight = squareSize.Height;
		int XVal = 0, YVal = 0;

		while ((int)ptr != stopAddress)
		{
			X = i % BmpWidth;
			Y = i / BmpWidth;

			XVal = (SqrWidth - X % SqrWidth);
			YVal = (SqrHeight - Y % SqrHeight);

			if (XVal == SqrWidth)
				XVal = X + -X;
			else if (XVal > 0 && XVal < BmpWidth)
				XVal = X + XVal;

			if (YVal == SqrHeight)
				YVal = Y + -Y;
			else if (YVal > 0 && YVal < BmpHeight)
				YVal = Y + YVal;

			if (XVal >= 0 && XVal < BmpWidth && YVal >= 0 && YVal < BmpHeight)
			{
				Val = (YVal * BmpStride) + (XVal * 3);

				ptr[0] = TempPtr[Val];
				ptr[1] = TempPtr[Val + 1];
				ptr[2] = TempPtr[Val + 2];
			}

			ptr += 3;
			i++;
		}
	}

	bmp.UnlockBits(bmpData);
	TempBmp.UnlockBits(TempBmpData);
}
								

Example

									Bitmap b = (Bitmap)Image.FromFile("rose.jpg");
ApplyGridPixelate(ref b, new Size(15, 15));