将Numpy数组转换为OpenCV数组。

I'm trying to convert a 2D Numpy array, representing a black-and-white image, into a 3-channel OpenCV array (i.e. an RGB image).

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Based on code samples and the docs I'm attempting to do this via Python like:

基于代码示例和文档，我试图通过Python来实现这一点:

import numpy as np, cv
vis = np.zeros((384, 836), np.uint32)
h,w = vis.shape
vis2 = cv.CreateMat(h, w, cv.CV_32FC3)
cv.CvtColor(vis, vis2, cv.CV_GRAY2BGR)

However, the call to CvtColor() is throwing the following cpp-level Exception:

但是，对CvtColor()的调用将抛出以下cpplevel异常:

OpenCV Error: Image step is wrong () in cvSetData, file /build/buildd/opencv-2.1.0/src/cxcore/cxarray.cpp, line 902
terminate called after throwing an instance of 'cv::Exception'
  what():  /build/buildd/opencv-2.1.0/src/cxcore/cxarray.cpp:902: error: (-13)  in function cvSetData

Aborted

What am I doing wrong?

我做错了什么?

2 个解决方案

#1

Your code can be fixed as follows:

你的代码可以固定如下:

import numpy as np, cv
vis = np.zeros((384, 836), np.float32)
h,w = vis.shape
vis2 = cv.CreateMat(h, w, cv.CV_32FC3)
vis0 = cv.fromarray(vis)
cv.CvtColor(vis0, vis2, cv.CV_GRAY2BGR)

Short explanation:

简短说明:

np.uint32 data type is not supported by OpenCV (it supports uint8, int8, uint16, int16, int32, float32, float64)
np。uint32数据类型不支持OpenCV(它支持uint8、int8、uint16、int16、int32、float32、float64)
cv.CvtColor can't handle numpy arrays so both arguments has to be converted to OpenCV type. cv.fromarray do this conversion.
简历。CvtColor不能处理numpy数组，因此两个参数都必须转换为OpenCV类型。cv.fromarray做这个转换。
Both arguments of cv.CvtColor must have the same depth. So I've changed source type to 32bit float to match the ddestination.
双方的观点都有简历。CvtColor必须具有相同的深度。因此，我将源类型改为32位浮动以匹配ddestination。

Also I recommend you use newer version of OpenCV python API because it uses numpy arrays as primary data type:

另外，我建议您使用最新版本的OpenCV python API，因为它使用numpy数组作为主要数据类型:

import numpy as np, cv2
vis = np.zeros((384, 836), np.float32)
vis2 = cv2.cvtColor(vis, cv2.COLOR_GRAY2BGR)

#2

This is what worked for me...

这就是我的工作…

import cv2
import numpy as np

#Created an image (really an ndarray) with three channels 
new_image = np.ndarray((3, num_rows, num_cols), dtype=int)

#Did manipulations for my project where my array values went way over 255
#Eventually returned numbers to between 0 and 255

#Converted the datatype to np.uint8
new_image = new_image.astype(np.uint8)

#Separated the channels in my new image
new_image_red, new_image_green, new_image_blue = new_image

#Stacked the channels
new_rgb = np.dstack([new_image_red, new_image_green, new_image_blue])

#Displayed the image
cv2.imshow("WindowNameHere", new_rgbrgb)
cv2.waitKey(0)

#1