I constantly get the Error Message: "OpenEXR "dwaa" compression has a bug for monochrome images, using "zip" instead"

[Anonymous]

Hey everyone.

I keep getting this error message when I hit the render in Arnold 4.0.1 (MtoA)

// Warning: [AiMakeTx] OpenEXR "dwaa" compression has a bug for monochrome images, using "zip" instead

Right now I have a simple scene: A plane and a lightdome with an HDRI from hdrmaps.com. Textures are from Poliigon.com (diffuse, glossy and displacement). I had that message before with other scenes but it never bothered me. Is this something I have to worry about? Renders come out fine, but the message is there all the time.

When I google the error message, Google is giving me a link: https://answers.arnoldrenderer.com/storage/attachments/5463-arnold.txt so I guess someone had the issue before, but all I get when clicking the link is an attached arnold.txt file (log file).

Maybe someone knows what it means and can explain?

[Stephen.Blair · Accepted solution]

It's a warning, not an error.

Arnold uses OpenImageIO to load textures, and OpenImageIO put in that warning to deal with

bugs with DWAA/DWAB compression of OpenEXR images in
the specific case of 1-channel images where tile size is either < 16 or not a power of 2.

https://github.com/OpenImageIO/oiio/pull/2378

[Anonymous]

I see. So there is nothing to worry about when Maya spits out the warning message?

[Stephen.Blair]

Right, you can ignore them

[jedwardsLR575]

Hey Stephen, I know this is a fairly old thread, but I did want to give you props for posting the reply. I recently swapped over to ACES and noticed the same issue happening to me. The XML file worked like a charm.

[tiziano.palumbo]

Hi Jared, which XLM file? Where i'll find it, and How it works? I would love to know. thanks 🙂

[sputknick]

Yes, I sure would like to fix this, not ignore it. Is there a way to get rid of this or change some setting in some texture somewhere? What is this XML file you are mentioning?

[thiago.ize]

The "compression has a bug for monochrome images" issue was fixed a couple years ago. Have you tried updating Arnold? https://www.arnoldrenderer.com/download/