Unexpected output while converting RGB image to LAB image
<p>I am trying to extract the LAB a-channel of a 32-bit RGB image. However I fail to read the image correctly and I get unexpected results.</p>

<pre><code>import cv2
org = cv2.imread('42.png', -1)
print org.dtype
# print uint8
lab_image = cv2.cvtColor(org, cv2.COLOR_RGB2LAB)
l,a,b = cv2.split(lab_image)
cv2.imshow('', a)
cv2.waitKey(0)
</code></pre>

<p>Original image:
<a href="http://labtools.ipk-gatersleben.de/images/42.png" rel="nofollow noreferrer">http://labtools.ipk-gatersleben.de/images/42.png</a></p>

<p>Expected output (ImageJ):
<a href="http://labtools.ipk-gatersleben.de/images/imagej_out.png" rel="nofollow noreferrer">http://labtools.ipk-gatersleben.de/images/imagej_out.png</a></p>

<p>OpenCV output:
<a href="http://labtools.ipk-gatersleben.de/images/python_out.png" rel="nofollow noreferrer">http://labtools.ipk-gatersleben.de/images/python_out.png</a></p>

<p>I also tried to read/convert the image with skimage but the result is the same...</p>