环境：windows 10 + VS 2017 + python 3.5
try1
用下面的命令直接安装，报错
pip install OpenEXR
try2
下载包，手动编译 -> 未能解决编译报错
参考：
Build OpenEXR on Windows
openexr windows 平台编译
try3
从下面链接直接下载wheel文件，注意选择和自己python版本匹配的文件下载
用pip(19.2 or newer) 安装下载的.whl 文件
Unofficial Windows Binaries for Python Extension Packages
读写例程
读入EXR文件，转换为HDR文件
def EXR2HDR(imDir, hdrDir):
File = OpenEXR.InputFile(baseDir+dataDir+Scene+'/'+Frame)
PixType = Imath.PixelType(Imath.PixelType.FLOAT)
DW = File.header()['dataWindow']
Size = (DW.max.x - DW.min.x + 1, DW.max.y - DW.min.y + 1)
rgb = [np.fromstring(File.channel(c, PixType), dtype=np.float32) for c in 'RGB']
rgbResize =[np.reshape(x,(Size[1],Size[0],1)) for x in rgb]
hdr = np.concatenate((rgbResize[0],rgbResize[1],rgbResize[2]),2) # H,W,C
# imageio.imwrite(hdrDir,hdr,format='hdr')
return hdr
获取exr图片的属性
print(file.header())
'''
{'displayWindow': (0, 0) - (1023, 767), #图片的大小
'pixelAspectRatio': 1.0,
'screenWindowWidth': 1.0,
'screenWindowCenter': (0.0, 0.0),
'channels': {'G': FLOAT (1, 1)}, #图片中的通道信息，此处是灰度，所以是G；如果是彩色的话，就是RGB，看情况；
'dataWindow': (0, 0) - (1023, 767),
'compression': ZIP_COMPRESSION,
'lineOrder': INCREASING_Y}
'''
为获取类型最大值/数据最大值
min_value = np.iinfo(im.dtype).min
max_value = np.iinfo(im.dtype).max
# docs:
# [`np.iinfo`] (machine limits for integer types)
# [`np.finfo`] (machine limits for floating point types)
HDR和LDR转换
def sRGBDeLinearize(linearsRGB):
linearsRGB = np.where(linearsRGB<=0.0031308, linearsRGB*12.92, 1.055*(linearsRGB**(1.0/2.4))-0.055)
return linearsRGB
'''
In both cases, the floating-point s value ranges from 0 to 1
When you're reading an sRGB image, and you want linear intensities,
apply this formula to each intensity:
'''
float s = read_channel();
float linear;
if (s <= 0.04045) linear = s / 12.92;
else linear = pow((s + 0.055) / 1.055, 2.4);
'''
Going the other way, when you want to write an image as sRGB,
apply this formula to each linear intensity:
'''
float linear = do_processing();
float s;
if (linear <= 0.0031308) s = linear * 12.92;
else s = 1.055 * pow(linear, 1.0/2.4) - 0.055; ( Edited: The previous version is -0.55 )
参考：
Using FreeImage convert hdr to jpg
What are the practical differences when working with colors in a linear vs. a non-linear RGB space?
openexr-making-sense-of-rgb-float-values
