FS7: Prores Recorded on Shogun from HDMI out: Banding/Posterization

[basspig]

Was grading some footage I shot with water in the distant background, out of focus. I have both the Prores footage and the XAVC footage. Was noticing that the blue area where the water is was splotchy. First I thought maybe my monitor wasn't running in 10-bit mode, so I applied a curve to the footage and exaggerated the contrast in the luma values occupied by the water. My god, it looked horrible, like a JPEG at quality setting = 1 in Photoshop.

So I checked the XAVC version of the same thing and it didn't have any obvious banding on the monitor. I applied the same curve to try to bring out banding and it was barely noticable; it looked like the normal version of the Prores without the test curve applied. Still looked good, albeit with whacky contrast and some visible macroblocks from the compression.

Which raises a big question: Is the Shogun only recording 8-bit color when in Prores HQ or is the HDMI output of the FS7 only 8-bit?

It seems that if I want less compression artifacts, I use Prores, but if I want dynamic range and smooth gradients, I need to use the internal recording to memory sticks. I thought Prores HQ was supposed to support 10-bit color. Where is the color depth being limited?

 

[digitalinnovations]

Did you ever sort this out?

 

[basspig]

Not yet. But I had a thought that perhaps because the Shogun was recording 1080P and the FS7 was in UHD, the realtime scaling for output may not be 10-bit. However, I see 'false color' even on UHD recordings. I noticed it with the moon shots last week. Cyan and magenta bands. More prevalent on bokeh where the out of focus elements are monochromatic, such as ripply water, lakes, etc.