Low Light Samples recorded Uncompressed

[paulcurtis]

Hi,

I'm investigating what i think might be an issue with the debayering or the sensor of FS700 at certain luminance levels but i want to know whether it's just my cam or all 700s. So i'm wondering if anyone has any uncompressed (or lightly compressed) footage they could send me. The artefacts are not visible in AVCHD only clean recordings. It may just be my camera (or recorder) but if you have some interior lowish light levels could you PM me and i can sort out a dropbox transfer or something similar?

I'll post my findings!

cheers
Paul

 

[paulcurtis]

Anyone got ANY externally recorded samples from the 700 even uncompressed still images? I've found the line patterns in a lot of normal footage too now that i'm looking for it. I'm keen to see whether it's in anyone else's footage before i escalate this to sony and do more testing.

I've included a sample image, i've emphasised it a bit and it's 200%, I can find it in all sorts of footage but not universally over a whole frame, it appears in different bands of luminance in patterns and situations i've not been able to understand.

What i need to do it to recreate this reliably. It could be the recorder (shuttle), the recorder settings (dnxhd), the cable (hdmi or SDI) or the camera. If i can grab some sample footage or get people to look at their source very carefully, looking for this pattern, that would give more weight when i speak to sony about it. If it's in anybody elses footage that points to the camera itself.

Normal AVCHD compression hides this totally.

I've ended creating some time consuming pipeline to remove this from the footage, so it's not a disaster for me (but i'm wickedly p*ssed off with it) but if it's the camera then there's a real issue. It looks like it might be, it's looks related to debayering to me. I'm trying to set up a controlled situation to test the recorder and at the same time run the SDI out straight into a decklink 4:4:4 i have, that should act as a control for testing...



cheers
Paul

 

[Gene Sung]

Wow, that's pretty harsh. I can't comment since I just record internally since I love to work light. Moral of the story, Sony needs to upgrade the internal codec to 4:2:2 50mbps so we won't need a recorder

yeah, yeah... I know that probably won't happen

 

[paulcurtis]

Gene,

I've emphasised it, most of the time it's pretty subtle but because of the postwork i'm doing i'm looking in a lot of detail at the footage. Of course once you see it then it becomes easier to spot it but that's compounded by the fact it's not universal or everywhere.

It could be as simple as a rounding error with various colour conversions down the line. Although i feel that it's unlikely to be the shuttle because i had two of them and the one connected to the FS100 does not show this. Also if it was the shuttle then i'm sure lots of people would have identified a problem.

I'd considered cables, because at that time i was using HDMI rather than SDI. But then i don't think cable issues would produce this kind of pattern either, i could be wrong.

As i mentioned above i need to find a test case and quantify the issue more but anyone that's running a 700 to an external recorder i'd love to see a frame or two.

For what it's worth i've had some fairly good success at creating a 2K master from these files (post work is all at 2K)

1080p -> Dark Energy Antimatter (very, very good noise reduction)
1080p -> 4K upscale with Instant HD (wavelet interpolation based)
Add subtle dither noise and sharpen
4K -> 2K with Resizer

The result is by upscaling and adding noise then the downscale 'improves' areas such as colour banding and also this vertical pattern noise, a subtle sharpen at 4K produces less ringing effects when downsampled too.

The end result is a massaged file with slightly better colour quality.

I've had to do all this in After Effects though because Antimatter is AE only. AE is a bit of a pain because when dealing with higher colour depths a lot of stuff doesn't work properly or can clip. So i can't work in YUV as the converter plugin is only 8bit! I'd rather be doing a lot of this in Nuke but i can script AE quite easily and for a processing operation is seems good enough.

cheers
Paul