No Support for Single Channel OpenEXR?

[Steffen Dünner]

Hi!

I just noticed that V-Ray for MODO doesn't seem to recognize single channel OpenEXRs (e.g. coming from MODO using the Save As... command).
RGB and RGBA ones work, but not single channel (i.e. GREY) images.

I also noticed that img2tiledexr.exe also converts single channel LDR images like e.g. PNGs to multichannel EXRs which is just eating up texture memory for no reason.
I always thought that the "Automatic" option automatically recognizes scalar / single channel images and converted them to single channel EXRs.

Cheers
Steffen

[vladimir.nedev]

About the first issue - I think it is fixed in our master development branch, once I merge the latest changes from it, it should work in V-Ray for MODO too.
I will write back here when that happens.

Greetings,
Vladimir Nedev

[Steffen Dünner]

Thanks!

[vladimir.nedev]

So I merged the changes from the master branch and single channel EXRs seems to work now. The change will be in the 2015-01-21 nightly build, as well as the official 3.00.05 open beta build.

The img2tiledexr tool also has a new option to let you specify a grayscale output EXR file (or grayscale with alpha).

Greetings,
Vladimir Nedev

[Steffen Dünner]

Wow, this sounds nice!

Will the img2tiledexr.exe in "Automatic" mode also automatically convert single-channel LDR files in single-channel EXRs or will I have to tell it before I start a conversion?

Cheers
Steffen

[vladimir.nedev]

I think it does automatically decide whether to output grayscale or color EXRs. The option just overrides the automatic behavior.
I haven't tested it though. You will have to check for your particular files.

Greetings,
Vladimir Nedev

[vladimir.nedev]

The UI actually has a new drop-down control called "Color mode:", which can be set to "Auto", "RGB" or "Grayscale".

In my previous posts I was talking about the command line options to the img2tiledexr executable.

Greetings,
Vladimir Nedev

[Steffen Dünner]

Thanks for adding support for greyscale EXRs.

In my first test it looks like it automatically generates single-channel EXRs from greyscale LDRs with both, the commandline and the GUI version.
The only problem so far is that I can't use DWA compression with greyscale images. The conversion process ends with a "Unknown error occurred. Unable to convert file "***.PNG"
Is that a limitation with DWA compression or a bug?

Cheers
Steffen

[vladimir.nedev]

It seems it is a bug in the OpenEXR library itself, this error is printed after a crash in OpenEXR.
Or maybe this compression is not supposed to be used with single channel EXRs at all.
Our guy is still investigating.

Greetings,
Vladimir Nedev

[Steffen Dünner]

Cool, thx!