Chaos Corona Forum

Chaos Corona for Cinema 4D => [C4D] Bug Reporting => Topic started by: Beejee on 2020-04-21, 12:30:19

Title: Why is there more contrast between 2 renders
Post by: Beejee on 2020-04-21, 12:30:19

Hello, Hope someone can help me or explain what is happening. I use Corona for Cinema4d and often I am trying to get more contrast and color depth in my renders. Renders and colours are sometimes too washed out and hdri skies have not the contrast I wanted them to have. So I am always trying to push the envelope but not always with satisfaction. But then I noticed that when I have rendered an Image in the Corona-VFB and I press render again that the rendered image gets for about 2 seconds much darker and with much more contrast especially in the sky and also colours are more intense(see attached images). This gives me the feeling that meaby there is something wrong with my settings? Or is this normal?And if so can someone tell me what is happening and how I can achieve this in my renders?

Thanks in advance,

P.S. In the attached images I used a corona sky with hdri and a little bit extra sun light.

Beejee

Title: Re: Why is there more contrast between 2 renders
Post by: HVB on 2020-04-21, 12:35:23

Looks like the image you see first is without tone mapping. Turn it off and see if you get that image.
But most likely you just need to adjust your exposure settings.

Title: Re: Why is there more contrast between 2 renders
Post by: Beejee on 2020-04-21, 13:18:33

Hello HVB,

Thanks for your reply! The first picture(the lighter one is with tone mapping) and when I turn of tone mapping the picture becomes more over lighted. And I also tried to achieve the more contrast affect like in the darker picture(the in between 2 renders screenshot) with tone mapping but I am not getting the exact same result. So that's why I am curious what is happening in between renders, just to learn from so that I can boost my images a bit further.

Title: Re: Why is there more contrast between 2 renders
Post by: Designerman77 on 2020-04-21, 15:09:31

Hmmm... that does not happen normally.
Also on C4D here.

Regarding your wish to get a more pushy light from the HDR: lower the gamma of the HDR.

Title: Re: Why is there more contrast between 2 renders
Post by: maru on 2020-04-21, 17:57:18

@Beejee - can you please explain what exactly you are doing, step-by-step? Or maybe record a short video demonstrating this behavior if possible?
Also, which exact version of C4D and Corona are you using?

Title: Re: Why is there more contrast between 2 renders
Post by: Beejee on 2020-04-21, 19:26:17

Thanks Maru and Designerman77 for replying!

@Designerman77 lowering the HDR gamma doesn't give the same effect. The main reason I am asking this in the first place is because I want to know if something is wrong with my settings in general. And in second place what it is what happens in between renders.

@Maru I recorded a screenshot video like you asked. Hope this explains what I mean. I attached it, if it will upload. You can see what I mean between 0.23 and 0.26 sec. Cinema4d is version R21.207 for Mac. Corona is version 5.0

Title: Re: Why is there more contrast between 2 renders
Post by: maru on 2020-04-22, 17:52:23

Thanks a lot for recording this, but I am not sure how to interpret it. It looks like the mouse cursor only moves at the beginning, and then stays in one place for the rest of the video, yet some buttons are pressed (?). Does it mean that you did something that didn't get captured in the video, or that you just started the rendering, stopped for it to finish, and then the brightness changed by itself?

Title: Re: Why is there more contrast between 2 renders
Post by: Beejee on 2020-04-22, 20:37:07

Hello Maru,

I already thought that this would be a strange video ;-). Sorry but I didn't know how to do it else. In the video you see a part of the VFB window. The only thing I do is pressing render at the beginning of the video. Then I only wait for the new render to start and do nothing. And between 0.23 and 0.26 sec the brightness/ contrast of the old render changes by itself before the new render appears. At the end of the video I switch to Quicktime to stop the video but that has noting to do with the render issue.
Hope this explains the video.

Title: Re: Why is there more contrast between 2 renders
Post by: TomG on 2020-04-23, 14:40:10

So this change in contrast is not in a final version of the render, just in between an old render and a new render? In other words, it has no effect on any final result that you want to use? Most likely it's just the tonemapping is turned off as the new render starts up, then is applied when the new render is underway. If so, you can always enable "Clear VFB between renders" and then you shouldn't see this brief in between section where tonemapping is not applied :)

Title: Re: Why is there more contrast between 2 renders
Post by: Beanzvision on 2020-04-23, 17:44:32

Hi Beejee,

Are you able to share this scene with us for testing?

Private Uploader:
https://corona-renderer.com/upload