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My script is supposed to take a greyscale image and map the values to hues.
#!/usr/bin/env python
import cv2
import numpy
infile = cv2.imread('Lenna.png')
infile = infile[:,:,0]
hues = (numpy.array(infile)/255.)*179
outimageHSV = numpy.array([[[b,255,255] for b in a] for a in hues]).astype(int)
outimageBGR = cv2.cvtColor(outimageHSV, cv2.COLOR_HSV2BGR)
cv2.imshow('dst_rt', outimageBGR)
cv2.waitKey(0)
cv2.destroyAllWindows()
It fails on the line with cvtColor and I get this error:
OpenCV Error: Assertion failed (depth == CV_8U || depth == CV_16U || depth == CV_32F) in cvtColor, file /tmp/opencv20150506-38415-u2kidu/opencv-2.4.11/modules/imgproc/src/color.cpp, line 3644
Traceback (most recent call last):
File "luma2hue.py", line 16, in <module>
outimageBGR = cv2.cvtColor(outimageHSV, cv2.COLOR_HSV2BGR)
cv2.error: /tmp/opencv20150506-38415-u2kidu/opencv-2.4.11/modules/imgproc/src/color.cpp:3644: error: (-215) depth == CV_8U || depth == CV_16U || depth == CV_32F in function cvtColor
Do I need to do something else to my outimageHSV array to make it ready for cvtColor?
843
To choose the correct code, we need to take in consideration that, when calling the imread function, the image will be stored in BGR format. Thus, to convert to HSV, we should use the COLOR_BGR2HSV code. As output, the cvtColor will return the converted image, which we will store in a variable.
cv2. cvtColor() method is used to convert an image from one color space to another. There are more than 150 color-space conversion methods available in OpenCV.
It returns the Coverted color space image. The default color format in OpenCV is often referred to as RGB, but it is actually BGR (the bytes are reversed). So the first byte in a standard (24-bit) color image will be an 8-bit Blue component, the second byte will be Green, and the third byte will be Red.
The error message implies that cv2.cvtColor expects an image with a (color) depth of 8 or 16 bit unsigned int (8U, 16U) or 32 bit float (32F). Try changing astype(int) to astype(numpy.uint8)
100
outimageHSV needs to be casted as uint8.
import numpy as np
outimageHSV = np.uint8(outimageHSV)
outimageBGR = cv2.cvtColor(outimageHSV, cv2.COLOR_HSV2BGR)
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