[scikit-image] image type issue and failed conversion

wine lover winecoding at gmail.com
Mon Dec 26 17:27:14 EST 2016


Dear All,

I was trying to use the above code segment for performing Contrast Limited
Adaptive Histogram Equalization (CLAHE).
def clahe_equalized(imgs):
    imgs_equalized = np.empty(imgs.shape)
    for i in range(imgs.shape[0]):

         print('imgs[i,0] ',imgs[i,0].dtype)
         print('imgs[i,0] ',imgs[i,0].max())
         print('imgs[i,0] ',imgs[i,0].min())
         imgs_equalized[i,0] =
exposure.equalize_adapthist(imgs[i,0],clip_limit=0.03)
    return imgs_equalized

The dtype is float64, maximum value is 255.0 and minimum value is 0.0

Running the program generates the following error message ( I only keep the
related ones)

imgs_equalized[i,0] = exposure.equalize_adapthist(imgs[i,0],clip_limit=0.03)
   raise ValueError("Images of type float must be between -1 and 1.")
ValueError: Images of type float must be between -1 and 1.

In accordance with the above error message and image characteristics, what
are the best way to handle this scenario.

I have been thinking of two approaches


   1. add imgs[i,0] = imgs[i,0]/255.   which scale it to 0 and 1
   2.  convert imgs[i,0] from float64 to unit8

but imgs[i,0] = imgs[i,0].astype(np.unit8) gives the error message such as
 imgs[i,0]=imgs[i,0].astype(np.unit8)

AttributeError: 'module' object has no attribute 'unit8'

Would you like to give any advice on this problem? Thank you very much!
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