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Member Since 30 Sep 2012
Offline Last Active Oct 15 2012 11:36 PM

Posts I've Made

In Topic: Speedy Image Likeness Comparison

11 October 2012 - 11:22 PM

Thanks to everyone (especially Spiro for the continued support!) your answers have been very helpful! I've learned some very important things here Posted Image

In Topic: Speedy Image Likeness Comparison

11 October 2012 - 02:26 AM

Wow, yes apparently GetPixel is incredibly slow. I don't understand the idea behind image locking, but I found this post that explains how to get access to the bitmaps byte array.


That cut the algorithms time down to 11 ms using the Marshal'ing method. To subtract the RGB values from each other just (aR+aG+aB)-(bR+bG+bB)?

In Topic: Speedy Image Likeness Comparison

11 October 2012 - 12:35 AM

I was going to move in to making it work for color images eventually, but I figured to start with greyscale cause it should be faster. Thanks for the tip about color images though.

Kinda expected it to go faster myself, so I wouldn't be surprised if something's wrong. Here's my function for it (C#):
private double GetEuclideanDistance(Image img1, Image img2)
			int dist = 0.0;
				Bitmap a = new Bitmap(img1);
				Bitmap b = new Bitmap(img2);
				if (a.Width != b.Width || a.Height != b.Height)
					System.Windows.Forms.MessageBox.Show("Target comparable image does not have the same dimensions. Cannot get Euclidean Distance.");
					return 0;
				int nRows = a.Height;
				int nCols = a.Width;
				for (int row = 0; row < nRows; row++)
					for (int col = 0; col < nCols; col++)
						int d = a.GetPixel(col, row).ToArgb() - b.GetPixel(col, row).ToArgb();
						dist += (d * d);
			catch (Exception ex)
				IEvo.ReportException(ex, "GetEuclideanDistance");
			return Math.Sqrt(dist);

My timings show that it takes around 400ms to complete every time. Only about 15 ms for it to copy the images in to Bitmaps.

In Topic: What language is better to learn - C# vs. Java

09 October 2012 - 08:07 PM

My first real language that I taught myself (other than web script languages) was C#. It's still my favorite for general purpose applications. C# isn't the best for cross-platform, but if you are mostly going to write Windows applications, C# and the .NET Framework offer you more. Finally, once you know C#, Java comes secondhand, they are *very* similar.