Chaos Corona Forum

General Category => General CG Discussion => Topic started by: dubcat on 2015-09-30, 04:39:50

Title: Photostop CC(2015) clamping .exr files
Post by: dubcat on 2015-09-30, 04:39:50

I made some custom HDR skies today. When I did my test renders the light intensity was waaaaaaay off. After some poking around, I found the problem. Photostop CC(2015) is reading and saving EXR files wrong somehow. Photoshop is clamping everything over +16.41 intensity down to +16.41. I'll post some of my test results bellow so you can see what I'm talking about. My workaround right now is to save stuff as .hdr. I just wanted to give you guys a heads-up so you don't clamp your images, save as .hdr from Photoshop.
I have tried every exr compression method, same result.

For this test I made a HDR of Corona Sun/Sky, 7070x3535px.

(http://i.imgur.com/1iMWG4e.jpg)

Real Corona Sun/Sky

(http://i.imgur.com/wERM9Y0.jpg)

HDR saved from framebuffer as EXR

(http://i.imgur.com/ufwkp5X.jpg)

HDR saved from framebuffer as HDR

(http://i.imgur.com/IH67E4s.jpg)

HDR re-saved from Photostop CC(2015) as HDR

(http://i.imgur.com/22DdDsf.jpg)

HDR re-saved from Photostop CC(2015) as EXR

(http://i.imgur.com/YEDW8vP.jpg)

Look at this shit, terrible.

Here are the values when you save from framebuffer or save from Photoshop as HDR

(http://i.imgur.com/T9tXDjJ.jpg)

Here are the values when you save from Photoshop as EXR

(http://i.imgur.com/BoEEXEB.jpg)

Title: Re: Photostop CC(2015) clamping .exr files
Post by: atelieryork on 2015-09-30, 10:47:38

Actually I think this is related or the same as the issue I posted the other week.

Are you using Contrast > 1.0 in your Tone Mapping? Doesn't matter if using CoronaCameraMod or just the VFB. Because if you are, it will clamp your image no matter if you save to EXR 16/32 whatever.

The only "solution" is to use Contrast = 1.0.

Try that and let us know.

Title: Re: Photostop CC(2015) clamping .exr files
Post by: dubcat on 2015-09-30, 17:44:13

I always render 1-1 linear in framebuffer and use tone mapping as my last node. But as you can see from the color picker images above, this is not Corona related.
When I open a fresh .exr/.hdr the sun is +20 intensity. After a ctrl+s the .hdr is still +20 intensity and .exr is +16 intensity.
I even did a full format on one of my PCs and installed Photoshop, same result. It's like Photoshop is corrupting everything above +16, because some programs read the new +16 value as 0.

I have uploaded a test for you guys. Open that .hdr, save it as .exr, close everything in Photosop and open the .exr again. The +20 value should be +16.

Title: Re: Photostop CC(2015) clamping .exr files
Post by: atelieryork on 2015-09-30, 17:58:57

I think you should post this on the adobe forums and see what response you get from Adobe on this. Looks problematic!

Title: Re: Photostop CC(2015) clamping .exr files
Post by: pokoy on 2015-09-30, 18:05:55

Yes, HDRs in Photoshop are handled differently than EXRs, up to a point where you simply can't paint over a hot pixel in both positive and negative values, it'll simply stay there and keep it's value no matter how hard you try to paint over it. As for their support, I guess HDR images are not high on their list.

Have you tried with all of the available EXR save options - integer, full and half float?

Title: Re: Photostop CC(2015) clamping .exr files
Post by: dubcat on 2015-09-30, 18:16:57

I just made a post over at Adobe, man is that site a mess to navigate.

Could you guys please try to resave the test.hdr image I uploaded in my last post, and see what the results are ?
The image was made in Photoshop, so we don't drag Corona into this.

Title: Re: Photostop CC(2015) clamping .exr files
Post by: romullus on 2015-09-30, 19:55:03

It's not only photoshop's problem. I did quick test with Picturenaut and it clips dynamic range when saving to exr too. Maybe it saves to half float rather than full float?