Convert .EXR image to pillow's `Image` with gamma encoding

exr_to_srgb.py

from PIL import Image
import OpenEXR
import Imath
import numpy
import numexpr as ne


FLOAT = Imath.PixelType(Imath.PixelType.FLOAT)

def exr_to_array(exrfile):
    file = OpenEXR.InputFile(exrfile)
    dw = file.header()['dataWindow']

    channels = list(file.header()['channels'].keys())
    channels_list = [c for c in ('R', 'G', 'B', 'A') if c in channels]
    size = (dw.max.x - dw.min.x + 1, dw.max.y - dw.min.y + 1)

    color_channels = file.channels(channels_list, FLOAT)
    channels_tuple = [numpy.frombuffer(channel, dtype='f') for channel in color_channels]
    
    return numpy.dstack(channels_tuple).reshape(size + (len(channels_tuple),))

  
def encode_to_srgb(x):
    a = 0.055
    return ne.evaluate("""where(
                            x <= 0.0031308,
                            x * 12.92,
                            (1 + a) * (x ** (1 / 2.4)) - a
                          )""")
    
    
def exr_to_srgb(exrfile):
    array = exr_to_array(exrfile)
    result = encode_to_srgb(array) * 255.
    present_channels = ["R", "G", "B", "A"][:result.shape[2]]
    channels = "".join(present_channels)
    return Image.fromarray(result.astype('uint8'), channels)