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I've been trying to convert an image to grayscale using opencv in Python but it converts the image to some kind of thermal camera image. What am I doing wrong? Here is the code for image below:
img =X_tr[9999]
plt.imshow(img)
plt.show()
img = cv2.cvtColor(img.astype(np.uint8), cv2.COLOR_RGB2GRAY)
plt.imshow(img)
plt.show()
img.shape
This image is taken from CIFAR10 dataset.
Thanks.
834
You have to explicitly set the cmap (colormap) parameter to gray , i.e. use plt. imshow(image, cmap='gray') . The default is viridis , obviously some green-ish/blue-ish colormap. Thanks!
Method 1: Using the cv2.Import the OpenCV and read the original image using imread() than convert to grayscale using cv2. cvtcolor() function.
It eliminates every form of colour information and only leaves different shades of gray; the brightest being white and the darkest of it being black. Its intermediate shades usually have an equal level of brightness for the primary colours (red, blue and green).
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.
Gray scale images, i.e. images with only one colorchannel, are interpreted by imshow as to be plotted using a colormap. You therefore need to specify the colormap you want to use (and the normalization, if it matters).
plt.imshow(img, cmap="gray", vmin=0, vmax=255)
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