Getting Rid of JPEG Artifacts

[pmaric]

Hello,

 

I am rendering an interior scene in Maya using global illumination and final gathering. My final images are being rendered at 1800px x 1200px, 300dpi. When I save my images and open them up in an external photo editing program (photoshop), all my images contain a ton of jpeg artifacts. Does anyone know how to get a clean render without these artifacts appearing in the final images?

 

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[DanGrover]

This might sound insultingly simple, but don't save them at JPEGs? If there's still some artifacts even if you save them as something lossless, like a .tif or a .tga, then it must be your textures themselves which contain the jpeg artifact.

[pmaric]

Thanks Dan!

 

I will try saving the renders as .tif and see if the artifacts still show up.

 

Is the jpeg file format not recommended for rendered stills?

[SandmanNinja]

JPG files are compressed, so data IS lost.

You should try an uncompressed format - BMP, TIF, etc

If you have the PSD plug-in, you can render straight to an Adobe Photoshop PSD file.

[pmaric]

Thanks SandmanNinja!

[DanGrover]

Quite! You should always aim to never compress any element of your production until the final part. So in this case, try and use uncompressed textures (though this is often impossible if photo sourcing them), and never compress the layers (except lossless compression, such as RLE or ZIP) that comprise the final composite. This means that for animated projects, you can end up with crazzzy file sizes. A short, 2.5 minute animation I worked on last year ended up being almost 500gb in file size, because of all the uncompressed image sequences and passes.

 

Then, finally, before putting it on the internet, compress in Jpeg (but try to keep the settings high). If you're not putting it on the internet, and so file size is less of a problem (say, a client is printing it) then never compress it, even at the end.

[pmaric]

well that was a very simple fix, thanks guys for your file format suggestions. I exported the still renders as .psd, .tif, and .bmp, and they all look much better than the jpeg version.

[SandmanNinja]

No worries, Pete. Welcome to the forums.

[Peter M. Gruhn]

> JPG files are compressed, so data IS lost.

 

Compression by itself is not a guarantee of loss. JPG is generally lossy compression (there is a lossless flavour that I don't really know anything about).

 

The field gets worse - a legal TIFF can be essentially a TIFF wrapper around a JPEG. Some applications ask before saving as a TIFF if you want compression and offer lossless options such as LZW and ZIP.

 

The advice to not save as JPEG is, of course, excellent. Note though that if you want to or have to or something, there should be an option to set the quality. Most applications ask about quality right in the save as process. I have seen some which hide it away in a separate options location. You can always turn the quality up. 3d renderings tend to have characteristics that don't take well to JPEG. These characteristics tend to lessen as the quality of the work increases.

 

A further caveat on JPEG is that each time you open and save a JPEG the image is freshly abused so quality decreases over time.

 

One nice thing about living in 2009 is that disk is cheap and bandwidth is pretty wide.

 

I don't mean this to sound like a dis on JPEG. It's a fine format and you should use it. But until you are more familiar with it keep a good copy of your images around and only use JPEGs when you are done or need to ship something out across the net. Turn quality up. I tend to the 7 to 9 in Photoshop or the 75% to 85% in ThumbsPlus. Spend a little time watching the size of files created and looking at the quality. You'll get a feel for it.