Normal map PNG artifacts?

ArasTM

Hey! 
Comparison:
I've always used PNG as the normal map format in my assets. I always thought that most of the artifacts and banding came from using 8bit maps rather than 16bit.
Recently when I baked 16bit PNG and it still had banding and such,  I tried 16bit TIF format and I was really pleasantly surprised.
What's really bugging me is that PNG is lossless, so why would it act like this? Also if I resave the PNG as TIF the artifacts disappear again. The comparison is done in Marmoset Toolbag. 

Thanks!

mod edit: deleted cute colours.

AlecMoody

One of two things are happening. Either the baker isn't correctly outputting  to png48 or marmoset isn't loading the full bit depth from the file. Try baking a 16 bit per channel png in another software and see if the problem still occurs.

Mark Dygert

Maybe I'm super old school but why would you use a compressed, lossy format at all? Especially when an engine is going to compress it further. You might as well feed it the highest quality image, uncompressed format you can.

TGA and TIF can be saved with no compression they are lossless, so you get a pixel perfect image for the engine to operate on. 

PNG is lossy, not lossless. It compresses and you lose detail in favor of a few bytes. The handful of mb's you save aren't worth the headache and loss of data.

Also PNG isn't a singular format, there are a few different ways to build and compress a PNG and it can be a nightmare to straighten out if the apps are building, interpreting, compressing and encoding them in different ways.

The way different apps handle PNG alpha is enough to send most people screaming for a more stable format. The way 3dsmax and Maya save PNGs aren't the same way Photoshop saves them. You can have a pipeline working just fine from 3dsmax/Maya to your engine but if you open and save it your png in PS, it could bork everything. 

Stick to the rock solid formats, stay away from compression, you have enough headaches to worry about =P

Bek

Mark Dygert said:

PNG is lossy, not lossless. It compresses and you lose detail in favor of a few bytes. The handful of mb's you save aren't worth the headache and loss of data.

Developed as a patent-free alternative to GIF, Portable Network Graphics (PNG) format is used for lossless compression and for display of images on the web.

Of course if you check reduce file format on save you're in trouble... but PNG is capable of lossless; it's not inherently a lossy format.

(edit: see below)

ArasTM

Mark Dygert said:

Maybe I'm super old school but why would you use a compressed, lossy format at all? 

Default PNG is lossless. The compression it offers only affects how the file is saved, not the actual information in it, it's like a zip file, not a color reduction. 

AlecMoody said:

One of two things are happening. Either the baker isn't correctly outputting  to png48 or marmoset isn't loading the full bit depth from the file. Try baking a 16 bit per channel png in another software and see if the problem still occurs.

The normal map is definitely baked well, because when I resave the PNG file as TIF it shows correctly again, I think you might be right about marmoset not loading the full bit depth, but why would this happen?

lorenzo_di_pietro

Although it's from 2014, this thread might help. 

ArasTM

@lorenzo_di_pietro it's a different issue, in my case TIFF solves the problem, but I'm trying to find out what's wrong with PNG / Marmoset.

ArasTM

@perna is there any option besides the one in the save dialog to change the color profile? Messing with the mode could very easily mess up the normal even further. 

lorenzo_di_pietro

ArasTM said:

@lorenzo_di_pietro it's a different issue, in my case TIFF solves the problem, but I'm trying to find out what's wrong with PNG / Marmoset.

Oh, I see. However, if it's Marmoset related you can always post your issue in the Marmoset section or call @EarthQuake 's attention directly.