Cineversity

Hello

I have a strange issue. I was creating an image using a frame coming from AE.  This is used as a texture on a plane that then falls like a curtain.
I apply the texture in the luminance channel, make sure my project is not set the Linear.  My Luminance channel sampling is set to none.
What is most noticeable is on the area of the frame where it says “Voie Lactee” and there is a spiral galaxy looking image, the amount of small stars on the periphery disappears.
I’m sharing a screenshot of the AB here : https://www.dropbox.com/s/vk586vakxuujpq5/2019-11-13_00h06_28.png?dl=0
Here is the project : https://www.dropbox.com/s/ry74esiezgkcuz2/ClothSim_v7.c4d?dl=0
And here is the texture.
https://www.dropbox.com/s/gqp4m5v0d701eqs/SpaceBG_ForCloth_3.psd?dl=0
And the render I’m getting
https://www.dropbox.com/s/wr3a9ke9mn2t268/ClothSim_v5_lumaShift.psd?dl=0

What am I doing wrong?

Hi Alex,

Thanks for the files. Very helpful.

This is not a problem between two different applications.

Do you remember when I mentioned having a higher resolution for the texture than the final result?

The next step is to switch off the MIP in the Luminance Channel. You might see already that it gets brighter a little bit, while in None, but perhaps also artifacts.
https://help.maxon.net/us/#6291
There are four suggestions for stills. Square might be the closest to your request, focusing on luminance only. Render a test. This should be much better, but be aware: This is not really ideal for animations!

The next step is to use an Anti-Alias that helps the details as well as the fine lines. The Ae output is pretty crisp with a certain amount of Anti Alias. With a higher resolution texture and a better (higher) Anti Alias Setting, the pixels of the texture will get closer to the result you had on the texture. I say closer, as any mix of pixels will average the results.

If I saw it correctly, in one image is an A/B line from the Picture Viewer. Have a look at the stars in A/B with 400% or even 800%, you will see that the renderings are softer, especially in MIP as texture setting.

Since I do not have a higher resolution texture here, you have to test this on your own. The texture is already anti-aliased. I would do a test render in None (Yes I know, that sounds weird!), Geometry, and Best set to 2x8. All with the larger texture, and then compare the outcome. Do you use Motion Blur on the falling Fabric? That would allow for the option None or Geometry perhaps.

As a cheap trick, you could lift a little bit the mid and a little bit more the highlights of the texture, so they give more energy into the render. This can be done with the Filter “shader. Perhaps set the Gamma in that shader to 1.2. Which brought the glow around the half dome elements back.

This is tricky and needs your eye, I can’t really set this up for you, I can only point to areas. Some tips I gave are certainly not for general purposes.

All the best

Thanks Sassi

This is all very useful.  Strangely I got better results by changing the gamma in the Picture Viewer than in the Filter shader…Not sure why, but the filter shader made everything a bit too bright. 
Anyways, I think I’m close enough!  Thanks again for taking the time to look into this!

You’re very welcome, Alex.

Adjusting before means that you put the texture pixels though the rendering, and with that, they average to a certain amount.

Correcting it later, if you are okay with the results, is certainly a way to go. The mixed pixel values get lifted that way. Changing later, also means that you do not have to work with still image settings, and might run into motion artifacts.

The energy that is in the texture pixels is merged during renderings, to say it in a simplified way. As a side note, if you would take an HDR from those stars, they might have way more than 100% brightness, which in return would influence the darker neighbor pixels different, and with this, the results a lot. However, that is not possible with 8bit/channel images nor in integer. But that is a longer story, and why I love working in Linear for over a decade.

Another observation of this is possible, while you have the same texture resolution as the final render resolution, then any animation increment not equal to a full pixel will change the brightness, eventually will create pulsing or flickering.
A typical example is given in movie credits when this is not understood. The text seems to follow a sine curve of brightness adjustments.
Example:
https://www.amazon.com/clouddrive/share/iElqpZc0bltUrDXwMvijrh6QwzWLojcvf8P6M0W0Bce

All the best