比较Python中的图像 [英] Compare Images in Python

问题描述

我需要比较两个图像，它们是该软件的屏幕截图.我想检查两个图像是否相同，包括图像中显示的数字和字母.如何做到这一点?

I need to compare two images that are screenshots of a software. I want to check if the two images are identical, including the numbers and letters displayed in the images. How can this be accomplished?

推荐答案

有以下几种方法可以进行正确的比较.

There are following ways to do the proper comparison.

• 首先是均方根差#

要衡量两个图像的相似程度，可以计算图像之间差异的均方根(RMS)值.如果图像完全相同，则该值为零.下面的函数使用差分函数，然后从所得图像的直方图计算RMS值.

To get a measure of how similar two images are, you can calculate the root-mean-square (RMS) value of the difference between the images. If the images are exactly identical, this value is zero. The following function uses the difference function, and then calculates the RMS value from the histogram of the resulting image.

# Example: File: imagediff.py

import ImageChops
import math, operator

def rmsdiff(im1, im2):
    "Calculate the root-mean-square difference between two images"

    h = ImageChops.difference(im1, im2).histogram()

    # calculate rms
    return math.sqrt(reduce(operator.add,
        map(lambda h, i: h*(i**2), h, range(256))
    ) / (float(im1.size[0]) * im1.size[1]))

• 另一个是精确比较#
• Another is Exact Comparison #

确定两个图像是否具有完全相同的内容的最快方法是获取两个图像之间的差，然后计算该图像中非零区域的边界框.如果图像相同，则差异图像中的所有像素均为零，并且边界框函数将返回None.

The quickest way to determine if two images have exactly the same contents is to get the difference between the two images, and then calculate the bounding box of the non-zero regions in this image. If the images are identical, all pixels in the difference image are zero, and the bounding box function returns None.

import ImageChops

def equal(im1, im2):
    return ImageChops.difference(im1, im2).getbbox() is None

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