Can pixel values of a hdr image have greater than 1?

Question

As far as I know, all pixel values of a hdr image should be less than 1 and greater than 0.

However, I tried to read hdr images and checked pixel values of one of images:

train_set_y_original = [cv.imread(fn, -1) for fn in train_img_folder] 

print(train_set_y_original[20])

But, some of values are greater than 1.

I tried both

print(train_set_y_original[20].astype('float32') 

and

print(train_set_y_original[20].astype('float64')) 

The results were same.

I don't understand why I got this result.

I need to make labels of hdr images so I need unchanged pixel values of a hdr image.

Answer 1

Yes, in case of limited range. For 10 bit 16-940 is used for Y' and Cb, Cr that is 16-960. Out of that it will be less that 0 and more than 1. That was used by xvYCC, BTW. And is used by Superwhite and Superblack. Not that it makes any sense with PQ transfer.

In case of full range, no in Y, Cb, Cr, but still yes in R', G', B'.