Convert 32 Bit Displacement to 16 Bit In Photoshop For Use In ZBrush

nickz · July 3, 2019, 8:05am

So I was looking through an old project of mine and for some dumb reason I deleted my original ZTL sculpts. roll_eyescry:

But…there could be hope yet. I do have all of my base cage geo and 32 bit displacement maps that I am using to render the character with in Maya Menalray.

So I know that I can take displacement maps (16 bit) and import them into ZBrush as an alpha, then add them to the displacement map area of the tool, set my intensity and mode and output the geo and get my sculpts back.

The only problem is there is bad aliasing that is occurring on the model when I apply the displacement. I know this isn’t a ZBrush issue at all. I have made a 16bit displacement map in Photoshop (16 bit grayscale with no color information saved out in PSD format) with smooth gradients and everything works as expected.

The problem arises when I convert the 32 bit file to 16 in Photoshop. (I’m using CS5 by the way.) The banding is happening during the conversion process. For some reason when I convert over this HDR filter tool pops up and this is the only way I can convert over.

Has anyone had any success in converting a 32 bit displacement map to a 16 bit in Photoshop and avoid this banding issue in ZBrush? If so please let me in on your conversion process…I would love to get this model back into good standing!

Thanks! NickZ.

zber2 · July 4, 2019, 1:04am

I don’t have Photoshop so I can’t help you there. As a suggestion though, have you tried ImageJ (free app) to convert from 32 to 16 bit. You would open your 32 bit image then go to ‘Image > Type’ and select 16 bit then save your image as a TIF for ZBrush.

marcus_civis · July 4, 2019, 1:04am

In the HDR Toning dialog chose Equalize Histogram from the Method drop down. I think that should give you the best conversion.

The problem with converting from 32bit to 16bit is that 32 bit can hold many more values, so when these are squeezed into 16 bits some of the different values are bunched together in a single 16bit data ‘slot’ causing the stair-stepping. The best way to avoid this is to be sure the whole of the 16bit range is used. The Equalize Histogram setting should do that.

nickz · July 4, 2019, 1:04am

Thanks for the response guys. Marcus, I have used this method…it is giving me the best results…but it is still causing the banding. I am starting to understand this conversion is not a good thing.

Marcus, any word on 32 bit support for Zbrush alphas? Also, what about vector displacement maps. We can now bake these maps out in ZBrush but can we really view them in the program correctly?

Thanks again for the replies, I guess until things change I’ll make note to use 16 bit displacement maps from here on out!

Peace-NickZ.

P.S. Just an FYI for anyone that is going through this looking for an answer, the imageJ program listed above will do the same thing that Photoshop does and crush the values down and cause the stair stepping in your mesh…it was worth a try though!