[Josh Litle]

Thanks Alan,

I understand your point about the YCrBr to RGB conversion. I do think that since both files are being converted to RGB using the same app (quicktime player) that presumably they are undergoing the same conversion process (accurate or not); then when viewed as RGB TIFF file in the same App (Photoshop) they theoretically will look the same (if the original Quicktimes were the same). But that’s really academic, since it relies on visual comparisons and many different variables in the chain.

I performed a much more accurate comparison that didn’t involve display issues or the human eye: I imported both QT’s onto seperate layers and composited them using difference mode (in AE), which only displays the parts of the files that are different from one another. If the files are identical this will result in an absolute black image (no difference between the files). However in this case you could clearly see a strong “ghost” image (much more than normal compression artifacts). I also compared the two files inside of FCP using the built in Vectorscope and waveform tools. Again the values were clearly different. Both of these methods should (in theory) bypass any display or color managing by Quicktime, FCP or the operating system. They are (in theory) mathematical operations based on the actual pixel values present in the files.

I still need to try the various export methodologies outlined above. I will report back on that.

josh
filmmaker

[Josh Litle]

Well, yes I did export from Quicktime. So I will attempt some tests following the recommendations above.

Regarding the monitoring question, yes I am monitoring on the desktop. That is why I tried creating RGB Tiff files – so I could compare the processed images in the same format in the same app (Photoshop).

Note to Apple: The FCP / QT / Compressor apps really should all handle this stuff (e.g. codec, bit-depth, colorspace, transcode) identically. As users we should not have to know all of these obscure work-around for simple export to be handled correctly. Grump. I always assumed the QT engine was at the heart of all three apps.

josh
filmmaker