Shadows in exr files gets dark when converted to 16bit

[suurland]

I'm having some issues with .exr files.. Still kinda hate this LWF workflow, old way seems so much easier :/

I've made a scene that you can get here if you want: http://www.suurland.com/tests/exr_test/exr_test.zip

Everything is default settings, there is a two planes and two spheres and a vraylight. the plane on the right has "Matte object" checked in its vray properties.

Screen shot:



When rendered and saved as OpenExr as 16bit half float and opened in Photoshop using ProExr it looks like this, which is as expected:



When I paint in some grey under the sphere on the right it looks like what you see below, this is also expected:



When opened in PhotoShop the file comes in as 32bit, but I really want to have a 16bit file as there are varies things that doesn't work in 32bit. So I convert it to 16bit and when I'm doing it I chose don't merge. and I get this result:


Now the shadow from the matte is suddenly a lot darker but everything stays the same, actually the Photoshop grid also gets darker!..

Why is this? How do I avoid it?

If anyone have a perfect way to work with exr I'll be all ears, when I look around every body seem to be doing something different.

/Thomas

[Deflaminis]

When you convert to 16 bit in photoshop it usually brings up a gamma conversion window... which options are you selecting?

Best one I've found is "exposure and gamma", just leave the defaults and hit ok. If you are using the default which is "local adaptation" then that's your problem. They should name that "no one ever wants this", because it's more accurate.

[suurland]

I usually pick "don't merge" when you convert to 16bit and then you don't get the "HDR Toning" menu, but if I do choose to merge and use "exposure and gamma" then I get the same result, if I pick "local adaptation" as you might think I'm doing then all colors change and not just the shadows.

[suurland]

Nobody got any ideas?

[samuel_bubat]

I'm having some issues with .exr files.. Still kinda hate this LWF workflow, old way seems so much easier :/

Tried LWf and skipped it immediately. Static Solution to a dynamic problem that LWF tries to solve by turning the wrong knob.
No offence... just trolling a little Don´t really have a solution for your problem, sorry.

[cheerioboy]

I never thought Photoshop did a great job at handling exr's. I've since switched to Nuke at the office. But I'll still creep back into Photoshop towards the end of a comp to do some quick overall adjustments to a .jpg or .tiff


It looks like something in the color profile switches when you switch between 16 and 32 bit.

also, the alpha changes, possibly related to the color profile change?


Photoshop is weird. (I'm testing with the latest, Photoshop CC (2014)

When you load the 16-bit image in with Transparency, it just asks if you want to merge when changing the mode.
When you load the 16-bit image with Alpha channel, it will give you the HDR Toning prompt.
But if you load the 16-bit image with Alpha channel, and then make changes, add layers, etc, it just asks if you want to merge when changing the mode.
But now even when you go through all the different Toning options, they all do the same damage to the alpha.
When you load the 16-bit image and copy the alpha and past it as a new layer, the look changes...

No idea if this is a bug or what.

[suurland]

yeah, no matter the method it looks the same, also tried after effects and it does the same.

how does it look in Nuke?

/Thomas

[cheerioboy]

Here's a snapshot from Nuke



I tested with both 16 & 32 bit EXRs and they looked the same.

[suurland]

Yeah, that looks a lot better, the ground plane is darker though, but I guess that's because the color you use for that is just darker.

So could this really be a problem with ProEXR?

/Thomas

[cheerioboy]

Yeah I think the ground plane is darker since it's just a flat 128 grey comped in, with no lighting from Vray affecting it.
Is ProEXR a plugin? I only used the default options within Photoshop to import the EXRs. No matter how you import the image with ProEXR, isn't Photoshop still going to mess with the alpha when changing modes?

One solution might be to save the alpha as a separate file, switch both the beauty and alpha to 16-bit mode, then combine and use the alpha render to create a new alpha channel. edit: actually, that made the shadow even darker...

[dans]

I did not try your scene, but did reproduce it using a simple black layer with layer transparency. This has nothing to do with the file format you use. You would get the same with a PSD via psd-manager

If you work in 32-bit mode (HDR) in Photoshop you always work in linear color space. All colors are blended in linear space. Photoshop then just converts the colors for display purposes when all layers are "combined" (you could say does gamma correction).

If you convert to 8 or 16 bits per channel, you no longer work in linear space (your color profile changes for example from Linearized sRGB to sRGB). This is why also the blended result of your layers changes. Photoshop now does not any longer do the blending in linear space. There is an option in the color settings under Advanced Controls "Blend RGB Colors using Gamma 1.0" you can use to get what you want. However this option is not per document so it will change the look of all your documents (so you will probably not want it on all the time, especially when exchanging PSD files with others). Note that this option only influences simple alpha blending (e.g. layers with transparency) The result of different blending modes will still differ between 8/16 and 32-bit mode even if using this option.



An alternative solution would be to convert the colors of the 8/16-bit document to the linearized color profile of the original 32-bit document.

Daniel