Hi David,
Thanks for the wondering article and the script. However, I encountered errors in your color decompose script. After checking the code, I found that:
“YCbCr ITU R470 256” should be written as “YCbCr_ITU_R470_256”
Likewise, “YCbCr ITU R709 256” should be written as “YCbCr_ITU_R709_256”
Hope this help.