Find a smaller image within another big one and fast

问题

Anyway to make this thing go faster ? coz right now it's like 6 seconds on the sourceImage the size of 1024x768 and template 50x50 around. This is using AForge, if anyone knows other faster and rather simple ways please submit. The task i'm trying to do is to find a smaller image within a screenshot. And preferably fast my limit is 1 second. The image i'm looking for is a red rectangle simple image and the screenshot is more complex.

System.Drawing.Bitmap sourceImage = (Bitmap)Bitmap.FromFile(@"C:\SavedBMPs\1.jpg");
System.Drawing.Bitmap template = (Bitmap)Bitmap.FromFile(@"C:\SavedBMPs\2.jpg");
// create template matching algorithm's instance
// (set similarity threshold to 92.5%)

ExhaustiveTemplateMatching tm = new ExhaustiveTemplateMatching(0.921f);
// find all matchings with specified above similarity

TemplateMatch[] matchings = tm.ProcessImage(sourceImage, template);
// highlight found matchings

BitmapData data = sourceImage.LockBits(
    new Rectangle(0, 0, sourceImage.Width, sourceImage.Height),
    ImageLockMode.ReadWrite, sourceImage.PixelFormat);
foreach (TemplateMatch m in matchings)
{

        Drawing.Rectangle(data, m.Rectangle, Color.White);

    MessageBox.Show(m.Rectangle.Location.ToString());
    // do something else with matching
}
sourceImage.UnlockBits(data);

回答1:

http://opencv.willowgarage.com/wiki/FastMatchTemplate - here you can find interesting idea for speeding up the template matching using two steps, first try to match downsampled images and when found match the original ones with smaller search region.

Also there is opencv implementation of template matching in matchTemplate function. This function is ported to GPU which can get significant speed up.

See the following

http://opencv.willowgarage.com/documentation/cpp/object_detection.html - matchTemplate function. http://opencv.willowgarage.com/wiki/OpenCV_GPU - about OpenCV functionality ported to GPU.

来源：https://stackoverflow.com/questions/9443862/find-a-smaller-image-within-another-big-one-and-fast

标签

image

image-processing

imaging

aforge