Banding issue from animation

[scanline]

Hello fellow keyshot folks:

Background banding is giving me headache. Due to the fact that my computer is not strong enough to render my work for my portfolio, I have decided to hire render farm service. But right now all the tests came back with banding issue. I am new to rendering so I don't know what to do. I don't want to spend extra money to fix something which I could myself but I need to know if I could.

Test results from mp4 and avi format came out almost exactly identical from two separate render farm.  I know they are just test renders but right now I don't know if that's compression from the test or the final render would be the same as well. Could this be HDR background problem and maybe I could tweak something to fix it?  I tried some test with After Effects; adding noise and changing to 32 bit float for bit per channel but to no avail so that leads me to suspect it is compression.

Due to the fact that I am planning to use render farm, I don't want my money to go down the drain. They are asking $15 dollars more to fix the issue so it is definitely something fixable but I don't know what it is and they obviously won't tell me. I would appreciate for anyone to offer some pointers.

Thanks.

[scanline]

Actually I went back to my project and I see the banding in keyshot itself. I missed that one. So it is something that could be fixed in keyshot before rendering because it looked like the render is exactly the same as what I see in my port view. I played around with contrast and size of the HDRI background but the problem persisted.

Edit: I went back and found out that the keyshot startup HDRI says 512x256. So could that be the issue, that it is too small?

[Rex]

Yes startup.hdr is there for simply that reason. It is quick to load and does a decent job of defining form and materials for initial setup. I recommend using a higher res environment with more variation in tone for your final renders.

However, subtle gradient banding can still be an issue depending on your display.

[LayC42]

As a quick test I would render one single frame as 32-bit tiff file.

Do you still recognise banding, then you can fix and test inside KeyShot as Rex suggested

Hope that helps to find the solution.

[Will Gibbons]

Hi Scanline,

You're seeing this because of what Rex hinted at and LayC42.

This isn't entirely due to compression, but the dynamic range of the image vs. the dynamic range your monitor is capable of displaying. Without getting into the technicalities, here's what will likely solve your problem, but it comes at the expense of effort and depends on your technical capabilities.

1. Render out frames as a 32-bit (ideally, but these create large files as a warning), or 16-bit (which may be a good quality/size compromise)
2. Load a frame into Photoshop's Camera Raw plugin (make adjustments if desired)
3. In Photoshop, convert into 16-bit image (banding may worsen slightly, but should be much better than originally)
4. Try converting to 8-bit and see how the image looks then if you need to get your file size down further
5. This process can be recorded and automated within Photoshop (but again, you need to know how)
6. Load your frames into your editing program of choice, but keep in mind different programs have different limitations
-Premiere Pro can only take 16-bit max and output 10-bit max and will likely give you the same banding issue, which is why you went through the process above to use Photoshop to handle the bit-depth to reduce banding
-After Effects however, can handle full 32-bit images as well as output that, but if you choose to do that, you'll need to do the bit-depth conversion in that program if you want a manageable file size when all's said and done. Also, that bit-depth will be lost when you export your media.

Of course, test this with a few frames on your own machine and be sure the results are satisfactory before paying for another service to do this.

Your last option is to slightly adjust your scene in KeyShot so that you have greater contrast in your background, environment or backplate so you're not trying to create such a subtle gradient that your 8-bit image or display (which is probably limited to 10-bit output) can't display it properly.

I'd recommend the last option above as it'll save you lots of frustration if you're not experienced with managing a 32-bit workflow. Long reply, but it's a common problem that hopefully this will shed some light on.

[scanline]

Wow, thank you guys for the input.

Yes, I figured that the startup was too low rez. I found and switched to a high rez hdri and now the banding is not as visible. Your suggestions helped me understand the issue now.

Thank you Will Gibbons for the detailed response there. That is indeed quite the work to squeeze the best result but doing the  process for every single frame will take me forever hah. The quality vs time/effort quandary again. But thank, that elucidate some of this mental fog for me as a newbie.

For my purpose, I think the higher rez image/ more tones should alleviate the problem. I guess banding is an issue that won't really completely go away depending on the monitors among other things.

Will do more tests but thanks for the inputs.

[mattjgerard]

Thanks for the info Will, that's a couple of great options to solve the issues. I will be bookmarking that response.

Gradients will always be a problem when displayng final images. The slighter the gradient, the more obvious the banding will be.