Dear Yuanyuan, First of all, it is not a good idea to initialize the array with values using `np.empty`. I'd recommend to use either `np.random.rand` or `np.random.randint`.
As for main point of your question, I believe you might need http://scikit-image.org/docs/dev/api/skimage.html#img-as-float (see also http://scikit-image.org/docs/dev/user_guide/data_types.html ). So, you can either create an array of floats [0:1) via `np.random.rand`, or create an array of uints via `np.random.randint`, and call `img_as_float`. Then `equalize_adapthist` should work flawlessly. Regards, Egor 2016-12-27 1:27 GMT+03:00 wine lover <winecod...@gmail.com>: > 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! > > > > _______________________________________________ > scikit-image mailing list > scikit-image@python.org > https://mail.python.org/mailman/listinfo/scikit-image > >
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