Is it possible to have 32bit EXR Smart Objects inside 16bit files?

[csscms]

Hi There, probably using incorrect search terms so sorry if this is easy.

I have 3D rendered 32bit HDR exr files I'd like to tone map in Photoshop.

Currently I'm...

• Opening the 32bit EXR in Photoshop
• Converting to 16bit via Exposure & Gamma (Local Adaptation looks weid as a starting point)
• Then converting to a smart object
• Adding the Camera Raw effect
• Adjusting then exporting images to various formats

Questions

1. Is there a way of doing this while keeping the 32bit image editable?
2. And is there a way of tweaking the 32bit while seeing the 16bit output?

I don't have experience with 32bit images so keen to hear how others do this.

Cheers, Ben

[rayek.elfin]

Why not convert the EXR to a smart object first, then convert the image to 16bit while retaining the layers (and avoid flattening the 32bit smart object layer)? Followed by assigning the Camera Raw effect as a live plugin to the smart object.

If need be, add the exposure and gamma to the 32bit version in the smart object.

Sidenote: Be aware that Photoshop doesn't convert to a full range 16 bit file. It converts (silently) to a 15bit +1bit range instead which means you will lose half the potential values of a full range 16 bit conversion.

Strictly speaking: 0-32767 + 1 = 0 - 32768 values. Any other image editor with 16bit support supports a range of 0-65535 values.

Photoshop turns a full range 0-1-2-3-4-5-6-7-8-9--etc to 0-0-2-2-4-4-6-6-8-8---, which can be an issue depending on what the file is supposed to be used for.

For photographic renders generally not an issue, but for HDR work, medical imaging work, and displacement mapping (for example) it could turn ugly.

If you need a full range 16bit file the 32bit conversion will need to be done outside of Photoshop.

[csscms]

@rayek.elfin 

Why not convert the EXR to a smart object first, then convert the image to 16bit while retaining the layers (and avoid flattening the 32bit smart object layer)? Followed by assigning the Camera Raw effect as a live plugin to the smart object.

That's what I tried first but when I edited the smart object using the camera raw effect, the preview in camera raw was no longer HDR, so I assumed it was no longer 32bit? Or is HDR something different?

Or is all the 32bit data there, it just previews as 16bit?

Sorry, haven't done this before so not sure what to expect. Cheers, Ben

[D Fosse]

I would assume you can just Place Embedded directly. Don't do anything to the 32 bit EXR, just leave it as-is. 

When you double-click the smart object thumbnail in the Layers panel, the embedded file opens in its host application for editing. Save and Close, and you're back in the updated master file. If the master file is 32 bit, HDR should be available.

I don't have an .exr plugin, or any other application that opens .exr, so I can't test. But this is how smart objects work with all other formats.

[csscms]

Thanks for that but when I double-click, it opens the original HDR version but on my HDR display, that doesn't help me decide how to map the HDR to a lower bit rate because I can't see how my adjustments will translate.

Can anyone confirm that if a file containing a 32bit smart object is converted to 16bit, that any adjustments made using the Camera Raw filter are being made in 32bit - while previewing in 16bit?

If you understand how this all works, then you can tell I do not! Cheers

[rayek.elfin · Accepted solution]

Camera Raw's output is 8bit or 16bit (which can be set in the preferences-->File Handling-->Camera Raw Preferences.

This means an automatic conversion to 16bit (or in Photoshop's case: effective 15bit). Which isn't an issue if your master file is also 16bit with the 32bit file placed as a smart object. (That is: if we do not care about Photoshop's limited 16bit image mode...)

Here is the result with me opening a 32bit rendered EXR scene from Blender directly in Photoshop, converting the layer as a smart object, switching the main file to 16bit image mode, and finally applying the Camera Raw plugin:

Full HDR support, as you can see.

And here the same file but placed as an embedded smart object:

No HDR support. It is deactivated. The quality sharply degrades, and it is no longer possible to edit in HDR mode. It is impossible to colour grade this properly as it (seemingly) only works in 8bit.

Based on my testing here, I wouldn't place it directly as an embedded smart object via File-->Open As Smart Object.

By the way, if I may ask: why use Photoshop at all for this work? I avoid Photoshop for jobs like these, because it adds another layer of potential mismatch and conversion issues as well as Photoshop's limitations in regard to 32bit files and in particular 16bit files. 

Instead, I use Blender's compositor to take care of this, and it also allows me to keep the pipeline a closed loop in regards to colour management and colour grading. For example, here is the above scene composited and edited in Blender's compositor:

This avoids the conversion step in Photoshop, and allows me to output a higher grade 16bit PNG. And tonemapping in Blender happens in full 32bit and supports Filmic, ACES, and AgX out of the box with various transforms. 

Of course, I am unsure which 3D software or rendering process was used to generate your @csscms EXR images. But even if you do not work in Blender for 3D rendering, you can still open the EXR files directly in the compositor. 

Ideally we want to stick to a 32bit workflow until the very end when we output the final 16bit PNG file - something that isn't possible in Photoshop. Davinci Resolve can also be used for this, but is a tad overkill for still images perhaps.

[csscms]

Ahh OK, never used Blender's compositor - will check that out. And you answered the question re 32bit smart objects in a 16bit file. Thank you - cheers

[rayek.elfin]

The about to be released R5 version of Blender has a number of quality of life improvements in the compositor. Recommended.

[csscms]

And v5 seems to improve the working colour spaces as well.

[rayek.elfin]

Yes, ACES 1.3 and 2.0 were added as defaults. I still prefer AgX myself - there are still issues with ACES that are resolved better in AgX (and even in Filmic). I work on a wide gamut P3 monitor, and R5 adds that option to select P3 compatible displays too. HDR screens are supported as well.

I find that a nodal compositing approach, while initially more complex looking, is preferable to a layer-based workflow for this type of work.