Monday, June 06, 2011

Photoshop tip #32 - Good gradations:

Ever been working in photoshop and had the dreaded banding issue show up while doing gradations - especially visible when using multiply layers? Well, your bandwidth (BITS) per color may be on the low side and that's what breaking up your gradations. So how do you solve this strange banding gradation problem?

Answer (and it took me a long time to figure this on out):

Bump up your Bits per channel in PHOTOSHOP from 8bit per channel (default) to 16 bits per channel: Image=>mode=> 16Bits/Channel.
Here is a GREAT article on this very topic:
http://www.artemis-design.com/difference-between-8-and-16-bit-per-channel.html

The down side of 16 bits per channel?
1) Massive file sizes. Simply put, the memory/file size of your image size will double.
2) Slow big or tricked out (complex) brushes. In the case of photoshop's new brushes - read that as REALLY SLOW big brushes.

Real world:

A lot of my layered production work gets well into the 700meg+ range and the thought of saving multiple 1.4+ gig PSD files is simply impractical for a lot of the Production Design work I do. BUT, 16 bit is much nicer when doing high end illustrations (with decent multiply-gradations) so...

My current rule of thumb: If it's not banding, stay 8bit. If you need higher fidelity and can afford the huge storage/memory/speed hit - go for 16 bit as the extended range is a beautiful thing.

/Ken H.

5 comments:

DSK said...

Introducing a small amount of noise can also help alleviate banding. If it's occurring due to multiplying layers, try adding noise to a 50% gray layer set to Soft Light.

Ken H. said...

Hi DSK,
thanks for the tip!
-I gave your method a try and It does indeed work to hid the perception of banding, but the price you pay in image degradation is pretty heavy.

This banding of gradations issue was such a problem with a production I was art directing ("Boom Blox") that we went to doing manual (hand painted) gradations instead of using the out of the box tool.

I did some simple tests tonight -black gradation-multiply layer- corner toward center sweep- over a field of bright blue- at 16bit/channel. There is still perceptive color banding issue but it was tolerable... It's not quite as pronounced as the 8bit/channel test but it's still there.

Then I kicked it up to a stupid heavy 32 bit/channel, did the same test, and that looked pretty darned good. ...BUT the darkness of the gradation in 32 shifted radically when I dumbed back down to 16 bit/channel and the image size got ridiculously big (4x 8bit/channel image). So I'm not going down that road in the near future.

There are definite limitations on the gradation tool in photoshop. For critical work I think I'll still end up using a large soft round brush with the hardness turned way down.

-Ken h

canvas artwork said...

amazing work, well done

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