Bit depth for Rhino's built in renderer

After running a few quick tests in v7 it appears 8 bits per channel is the limit regardless of what format is used.

So for example using EXR format and saving a Distance pass is only 8 bits.

Am I missing something … is 8 bits per channel still the limit or is there a way to specify 16 bits per channel?

I don’t see any way to completely turn off some sort of clamping or toning that will kill the high dynamic range, no…the extended data is there, but apparently no way to get it out.

It is curious … including OpenEXR as an export format would appear to indicate higher bit depth is possible, but if all that can be exported is 24 bit RGB color (8 bits per channel) there really would not be any benefit.

Well it’s to allow you to adjust exposure after rendering, it dates back to Flamingo…but I at least don’t see any way to just turn that stuff off and get the HDR output.

Bit depth is independent of exposure, at least in other apps.
I don’t know the history, so maybe there is an 8 bit per channel limit.

Rhino Render in v7 internally renders to float channels, so 32 bits per channel is definitely possible.

We’ll have to ask @johnc for info on how many bits are saved to EXR and TIFF.

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A 16bit support for png output would be great too.

@cdordoni I just saved out an EXR with the depth channel. Opening it up in Blender tells me it is RGBA float, not 8 bit. How do you determine the EXR is saved as 8 bit?



Thanks for looking into this.

After doing a test again, I do find the EXR is saving 16 bits per channel but PNG and TIFF are not.

You will need Photoshop or an application that can use the Photoshop filter format for this because a specific plugin is required.
Use Count Colors at Telegraphics - Free plugins for Photoshop & Illustrator...and other software

Count Colors does not work with the full bit depth of the EXR image so I had to convert it to 16 bits per channel in Photoshop

The Telegraphics plugin is the ONLY way I have found to count unique colors in images with 16 bits per channel. GIMP, Irfanview, Faststone may show the wrapping format is higher bit depth but the reported unique colors indicate the data is only 8 bits per channel when the image does contain 16 bits per channel data.

For this I logged RH-64094 Support higher-bit channels for PNG and TIFF

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Great …Thanks!