bool类型图像到uint8的转换

Question

I used the link below for thresholding of my images. https://github.com/subokita/Sandbox/blob/master/otsu.py but my images was grayscale and I didn't as same as the link. now I want to use the function otsu2 or otsu1

img=cv2.imread('E:/tilpixs2/23_1050_450_5.0X/til1.G.png')

rows,cols,channelsNo=shape(img)

# create 256 bins histogram
hist = histogram(img, 256)[0] 

# apply the otsu thresholding
thresh=otsu2(hist,rows*cols)
img2=img>=thresh

plt.imsave("E:/tilpixs2/img2.png", img2)

img2.dtype  #it is boolean 

To convert img2 to uint8, I did some convertions. Some of them are here"

img2.dtype='uint8'

or

img4=img2.astype(uint8)

or

npyage = np.array(img2)
img3=img2.np.uint8

But when I check the image when saved, the bit depths in properties of image is 32. I'm totally confused, What should I do? what does 32 in bit depth means? I want an image of 8 bit int

This is the properties of image

Answer 1

Assuming that plt is an object reference to Matplotlib.pyplot, the module doesn't respect color depth for it's imsave call. OpenCV's imsave will respect the datatype. See the documentation for pyplot's image save call here: https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.imsave.html

img = cv2.imread('E:/tilpixs2/23_1050_450_5.0X/til1.G.png')

rows, cols, channelsNo = shape(img)

# create 256 bins histogram
hist = histogram(img, 256)[0]

# apply the otsu thresholding
thresh = otsu2(hist, rows * cols)
img2 = img >= thresh

img3 = img2.astype(uint8)

# Choose one of the options below depending on required format

# Save all 3 channels as a 24bpp grayscale image
cv2.imwrite("E:/tilpixs2/img2.png", img3)

# Save a single channel as a 8bpp grayscale image
cv2.imwrite("E:/tilpixs2/img2.png", img3[:,:,1])