Hi Stephen,
Thanks for your detailed advice. I am using the first method to get the average luminance and the luminance is almost 1240 which seems OK. Meanwhile, I tried the second way but the result is 31.09 that is too small.
I guess this problem is related to the command “pcompos”. Once I got the RGB values which was also much smaller of a cropped HDR image using “pcompos” and “pvalue”. You can refer to this post:
