针对arcLength的Python错误的OpenCV [英] OpenCV with Python error for arcLength

问题描述

我的代码中存在问题，无法为其找到合适的解决方案。我使用的是Python 2.7.10和OpenCV 3.0。我读了两张图片，想要将其中一张图片（模板）与另一张图片相匹配，但我收到以下错误：

I have an issue in my code and can't find a proper solution for it. I am using Python 2.7.10 and OpenCV 3.0. I read two images and want to match one of the pictures(a template) with the contours from the other but I get the following error:

error: (-215) count >= 0 && (depth == CV_32F || depth == CV_32S) in function cv::arcLength

我的代码看起来像这样：

My code looks like this:

gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
gray = cv2.bilateralFilter(gray, 11, 10, 17)
edges = cv2.Canny(gray, 100, 20)

contours,hierarchy, _ = cv2.findContours(gray, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
for c in contours:
    ret = cv2.matchShapes(c, compare, 1, 0.0)
    if ret < 0.5:
        peri = cv2.arcLength(c, True)
        approx = cv2.approxPolyDP(c, 0.02 * peri, True)

灰度和比较图像均为灰度。错误显然是说我需要我的数组是浮点数或双数，但我不知道如何在python中转换它，我发现很多例子，函数工作，代码似乎几乎相同。

Both gray and compare images are grayscale. The error is obviously saying that I need my array to be of floats or double, but I got no idea how to convert it in python and I've found many examples with the function working and the code seems almost the same.

此外，在大多数应用程序中，我注意到在大多数示例中，findContours（）函数返回2个值，但如果我不给它3，我会收到错误。

Furthermore, in most applications I've noticed that on most examples the findContours() functions returns 2 values, but I get an error if I don't give it 3.

请帮我找到问题！

推荐答案

这个错误实际意味着什么是你的图像是32位浮点数而不是整数。特别是8位无符号整数。我相信，这对应于OpenCV所理解的灰度图像。您可以使用其他类型的基础数字类型，它仍将以灰度模式显示在查看器中，但要了解您使用的查看器将重新调整它（安静地）以显示它。

What that error actually means is that your image is in 32 bit floats and not integers. Specifically 8 bit unsigned integers. I believe, this corresponds to a grayscale image as its understood by OpenCV. You can have other types of underlying number types and it will still display in grayscale mode in a viewer but understand that the viewer you use will rescale it (quietly) to display it.

我建议您尝试的是：

gray_image = cv2.convertScaleAbs(img)

不知道返回的东西是怎么回事。

Not sure what is going on with the return thing.

我也道歉，我误解你要求cv2并且你问cv3。我认为它应该足够相似，给我一些时间来检查它。

Also I apologize, I misread that you're asking for cv2 and you're asking cv3. I think it should be similar enough, give me some time to check it out.

OpenCV3有berak在这个问题中回答了一些不同的语法：
opencv 3 beta / python中的findContours和drawContours错误

OpenCV3 has a bit of a different syntax as answered in this question by berak: findContours and drawContours errors in opencv 3 beta/python

opencv 3略有此处更改
语法
，返回值差异：

opencv 3 has a slightly changed syntax here, the return values differ:

cv2.findContours(image, mode, method[, contours[, hierarchy[, offset]]]) → image, contours, hierarchy

这篇关于针对arcLength的Python错误的OpenCV的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！