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I would like to read an environment map in *.hdr file format. It seems that very popular libraries doesn't support .hdr file reading, for example, OpenCV, PIL etc.. So how to read a .hdr file into a numpy array?

Dawei Yang
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2 Answers2

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I found ImageIO very useful. It can handle many image file formats including .hdr images. Here is the list: ImageIO Formats

It can be easily installed using easy_install or pip.

Dawei Yang
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    When I try to load an hrd-image using the imageio module in Python 3 I get the error message `ValueError: Could not find a format to read the specified file in mode 'i'`. Do you know what that means or how to solve it? – HelloGoodbye Feb 26 '17 at 15:03
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    It means that you did not specify the format imageIO should use when reading the file and the auto format detection is coming up with empty. Try running it again with `format='HDR-FI'` as an argument. This will most likely tell you that the FreeImage library is not installed and then it will tell you how to install it. (Spoiler alert: you install it by running `imageio.plugins.freeimage.download()`). After that, it should work. – Dr K May 17 '17 at 14:40
  • I get that prompt, but am unable to download the library because the SSL certificate fails to verify – Fractaly Feb 03 '20 at 03:09
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For some reason when I was trying to load a MRI image in .hdr format using format='HDR-FI' it was returning Could not load bitmap <path to image>: : RGBE read error

But if you type imageio.show_formats() it returns a list of formats including "ITK - Insight Segmentation and Registration Toolkit", where it shows that it can handle .hdr images as well.

So my alternative was to use:

pip install itk

hdr_path = "<path to image>"
img = imageio.imread(hdr_path, 'ITK') # returns a tuple

img = np.array(img) # transforms to numpy array
solisoares
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