Chromatic Noise on Ursa Mini 4k

I'm aware that the Ursa Mini 4k isn't a low light camera, however I was having some pretty severe issues on a test shoot today with heavy chromatic noise even in mid-greys with daylight footage on lossless raw.

Here is a 50% shot of the entire frame:

Full image half size

full-image-sample.jpg (445.23 KiB) Viewed 1835 times

Here is a 200% view of the details:

Detail Focus, 200% to make it more visible.

detail-focus-sample.jpg (65.44 KiB) Viewed 1835 times

Any ideas what is going on here? I've graded the image a little, but not substantially. It's actually even more noticeable pre-grading. It's pretty noticeable even in the directly sunlit portion of the bridge's side and gets much worse in the shadow underneath, though that's more like 25% or so I'd guesstimate. Is this normal for this camera? It seems far noisier than other test footage I've seen, but those have also normally been through some pretty heavy compression that may simply be obscuring the noise.

For anyone else that sees the images and worries. I should note that after I finished my test and exported to a more consumption friendly format, the net impact of the blending over time was that most of this noise was completely or near completely removed. I actually ended up very pleased with the final image quality of the finished video, but would still love some insight as to whether other people see similar things on theirs.

AJ, remember the BMD cameras do zero noise suppression in raw. That's a feature, not a shortcoming. Usually cleans up nicely in post.


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...I was having some pretty severe issues on a test shoot today with heavy chromatic noise even in mid-greys with daylight footage on lossless raw...Is this normal for this camera?

Yes, I'd say that's looks about right for the UM4K. I see the same type of noise in mine. I rather like it as it looks a lot like film grain.

As Rick points out, there is no noise suppression in RAW, so what you're seeing is actually pretty typical from nearly any image sensor. You'd be surprised just how much the compressed formats reduce noise just in and of themselves. Noise reduction is one of the first steps of discarding data during compression.

Yeah, all my previous RAW work was on the photo side. All my previous video work wasn't at the RAW level. My 5D Mark iii makes exceptionally clean images unless it gets pretty dark for a still, but it is also doing one very high resolution image at a time rather than a large number of smaller images very quickly. I realized I was comparing apples and oranges, but hadn't really realized just how much of an impact the temporal nature of video frames would make it feel more film grain like and then consumer formats just completely clear it up.

It made for an interesting experience as I got done with my test shoot, looked at the raw images and went "ut oh" then looked at them playing back smoothly in a high quality video after grading and was like "oh, that's actually just fine" and then I did a consumer compression pass for Youtube and it just looked fantastic. In retrospect it all makes sense, just didn't really realize just how strong the impact would actually be, even if the theory behind it makes perfect sense.

I'd read a bit about some of the earlier cameras having quality control issues and wanted to make sure that it wasn't the case with mine, but after a few more days messing with it and seeing how beautifully it actually plays out and the responses here, my mind is at ease and I'm completely thrilled with the quality. Only real problem I've had is one stuck pixel on the LCD, but that's hardly the end of the world.

Thanks for the feedback.

Good, AJ. Pixel peeping on raw images has its place, but the best judgments of the film are made viewing your masters for your personal reference and your client deliverables for public consumption. If you're doing the post work, at least to the edit stage, shoot the best quality codec you can justify and that means 12bit colour for acquisition regardless of your output in my opinion.


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If you're doing the post work, at least to the edit stage, shoot the best quality codec you can justify and that means 12bit colour for acquisition regardless of your output in my opinion.

Yeah, my current preferred workflow whenever I have sufficient media to be able to support it for the project size is shoot RAW, do an initial color pass to get it close enough I'm not going to lose anything going to a more efficient 4444, convert to that for editing purposes and archival sources to drop down the size a little bit, but not too much, then edit in that. I'm not new to video workflows in general, I did them extensively before jumping over to photography, but just haven't had the RAW capability before in video (Previous video work was SD era with GL2s and VX2000s.) so adapting things to the new environment.

Depending on your personal preferences of course (and if you're not working with green screen, CGI, special effects) you can edit and grade quickly in Resolve on a very modest (proxy) timeline, but when you generate your deliverables, be sure not to use your cache renders but revert back to your raw originals at best quality.


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Oh, I'm downscaling to something more affordable to work with. My main reason to shoot RAW is just to have the ability to finesse the exposure and color of the footage to where I want it. After that, I encode it to a new master that is more affordable to keep around. I might still end up using a proxy off that master for editing, but I can't really afford to do RAW masters at this point, my wife won't allow me to keep around shelves full of HDDs.

If it's a fairly short run project, I might try to proxy it and generate final off the RAWs but I'd have to not be working on much else at the time and still don't particularly like not having an archival master that can regenerate the finished product. I'll mess around with both as I work on refining my workflow to something I like though. Maybe in the 4k RAW shooting space it will be worth altering my obsession with archiving master sources and instead archive sources lower than what was used in the final output. Thanks for the suggestions.