解析hdr图像文件的python实现

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如题
import cv2import numpy as npdef rgbe2float(rgbe):    res = np.zeros((rgbe.shape[0],rgbe.shape[1],3))    p = rgbe[:,:,3]>0    m = 2.0**(rgbe[:,:,3][p]-136.0)    res[:,:,0][p] = rgbe[:,:,0][p] * m     res[:,:,1][p] = rgbe[:,:,1][p] * m     res[:,:,2][p] = rgbe[:,:,2][p] * m    return res        def readHdr(fileName = 'belgium.hdr'):    fileinfo = {}    with open(fileName, 'rb') as fd:        tline = fd.readline().strip()        if len(tline)<3 or tline[:2] != '#?':            print 'invalid header'            return        fileinfo['identifier'] = tline[2:]        tline = fd.readline().strip()        while tline:            n = tline.find('=')            if n>0:                fileinfo[tline[:n].strip()] = tline[n+1:].strip()            tline = fd.readline().strip()        tline = fd.readline().strip().split(' ')        fileinfo['Ysign'] = tline[0][0]        fileinfo['height'] = int(tline[1])        fileinfo['Xsign'] = tline[2][0]        fileinfo['width'] = int(tline[3])        data = [ord(d) for d in fd.read()]        height, width = fileinfo['height'], fileinfo['width']        if width<8 or width>32767:            data.resize((height, width, 4))            return rgbe2float(data)        img = np.zeros((height, width, 4))        dp = 0        for h in range(height):            if data[dp] !=2 or data[dp+1]!=2:                print 'this file is not run length encoded'                print data[dp:dp+4]                return            if data[dp+2]*256+ data[dp+3] != width:                print 'wrong scanline width'                return            dp += 4            for i in range(4):                ptr = 0                while(ptr < width):                    if data[dp]>128:                        count = data[dp]-128                        if count==0 or count>width-ptr:                            print 'bad scanline data'                        img[h, ptr:ptr+count,i] = data[dp+1]                        ptr += count                        dp += 2                    else:                        count = data[dp]                        dp += 1                        if count==0 or count>width-ptr:                            print 'bad scanline data'                        img[h, ptr:ptr+count,i] = data[dp: dp+count]                        ptr += count                        dp +=count        return rgbe2float(img)if __name__ == '__main__':    m = readHdr()    m1,m2 = m.max(), m.min()    img = (m-m2)/(m1-m2)    m1 = m[:,:,0].copy();  m[:,:,0] = m[:,:,2]; m[:,:,2]=m1    cv2.imwrite('tmp.jpg', img*255)
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