如何使用OpenCV MatchTemplate? [英] How do I use OpenCV MatchTemplate?

问题描述

我正在尝试在另一个图像中查找图像.

I'm attempting to find an image in another.

im = cv.LoadImage('1.png', cv.CV_LOAD_IMAGE_UNCHANGED)
    tmp = cv.LoadImage('e1.png', cv.CV_LOAD_IMAGE_UNCHANGED)
    w,h = cv.GetSize(im)
    W,H = cv.GetSize(tmp)
    width = w-W+1
    height = h-H+1
    result = cv.CreateImage((width, height), 32, 1)
    cv.MatchTemplate(im, tmp, result, cv.CV_TM_SQDIFF)
    print result

运行此命令时，一切执行正常，不会引发任何错误.但是我不确定从这里开始该怎么做.该文档说result存储比较结果图".我尝试打印它，但是它给了我宽度，高度和台阶.

When I run this, everything executes just fine, no errors get thrown. But I'm unsure what to do from here. The doc says that result stores "A map of comparison results". I tried printing it, but it gives me width, height, and step.

如何使用此信息来查找一个图像是否在另一个图像中/位于该图像中?

How do I use this information to find whether or not one image is in another/where it is located?

推荐答案

MatchTemplate返回相似度图，而不是位置. 然后，您可以使用此地图查找位置.

MatchTemplate returns a similarity map and not a location. You can then use this map to find a location.

如果您只想寻找一个匹配项，则可以执行以下操作来获取位置:

If you are only looking for a single match you could do something like this to get a location:

minVal,maxVal,minLoc,maxLoc = cv.MinMaxLoc(result)

然后minLoc具有最匹配的位置，而minVal描述了模板的适合程度.您需要确定minVal的阈值，以确定您是否认为此结果匹配.

Then minLoc has the location of the best match and minVal describes how well the template fits. You need to come up with a threshold for minVal to determine whether you consider this result a match or not.

如果每个图像要查找多个匹配项，则需要使用非最大压缩等算法.

If you are looking for more than one match per image you need to use algorithms like non-maximum supression.

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