Gardients in PS7.0 printing with stripes

[Craig Dumesny]

Hi all,

I have a small problem with gradients in PS7.0 that some of you may be able to help me with.

I had been running my laptop PC with a TFT screen at 1400x1050(?) resolution and working in PS with no apparent problems. I had designed a digital wedding album with some of the layouts having gradients around the edge or on one page in particular I ran a left to right grey gradient down the whole page as a background with one small image on that page. All looked absolutely fabulous on the screen but when they were printed/outputted from Pegasus the gradients are 'stripy' and not seamless as they appear on screen.

I rang the lab and they say that this is a problem with Pegasus, however I have seen other's work from interstate who use gradients all the time and they don't have this problem, but they don't know why.

After reducing the screen res on the laptop to 1024x768 the problem with the gradients appears as it does when outputted to the Pegasus machines.

To give you further info I am working on TIFF files at 250dpi.

Can anyone help?

Thanking you in advance.

[Doug Nelson]

It sounds like "banding". Try adding a tiny bit of noise to the gradient. Also, make sure 'diffusion' is turned on when you make them (an option bar checkbox).

It's ironic that this is more of a problem with better printers.

[Craig Dumesny]

Thanks Doug,

I have put in a bit of noise in and this does fix the problem per se, however I was wondering if there was an easier answer. And yes, it is banding that I am getting.

[Stephen M]

More info than you probably want is in this archive, on why grads band and how to fix it, among other things:

http://www.ledet.com/margulis/ACT_postings/ACT-Banding-16%20bit-8-bit.html

Are you editing the gradient after it's creation with a level or curve?

Is this a custom printer profile, stock OEM profile for the ink/stock or no ICC CM and the numbers sent raw to the printer with or without printer settings?


Stephen Marsh.

[Craig Dumesny]

Hi Stephen,

Phew...lot's to get through but it is making me understand what's going on much better.

I am not editing the gradient with a level/curve adjustment - should I try this?

"Is this a custom printer profile, stock OEM profile for the ink/stock or no ICC CM and the numbers sent raw to the printer with or without printer settings?" Just using sRGB, but after ready the archive stuff I might just try different ICC profiles.

Thanks.

[Stephen M]

No do not edit the perfect CG gradient with levels or curves - that usually adds more banding (it is explained somewhere in the archive, there are only a limited amount of tones available, and a computer grad is perfect, so any edits may add to the problems as the original perfect values will now be less and there will not be the even space between steps and thus bands).

The reason profiles were mentioned is that they can have a big effect on the output - if using a poor profile banding may be apparent when another profile may not.


Stephen Marsh.

[Stephen M]

Craig - I recommended that no levels/curves moves be made to the gradient, which is often good advice - but who knows, it could help in this case? But I would not bet on it, with luck this could work in some cases.

What I would recommend is the equalize command on a gradient, but if this is a perfect computer generated gradation with no edits to the gradient after creation (including blending modes on upper layers which affect the gradient) - then equalize should not have much or any effect, but again - you never know until you try.

The condensed version of the archive I sent goes like: Gradients can be hard to reproduce without bands. Vector grads often have more issues than raster grads. Try not to edit grads. Keep in mind that printer driver or colour management settings will often use a behind the scene tone curve and grads may be affected anyway - even if you are not doing this to the actual file as you work. Adding dither in the grad or more heavy noise are recommened (smart noise may be needed to protect highlights/shadows from gaining noise).


Stephen Marsh.

[Craig Dumesny]

Thanks all. Adding noise is working well...I will experiment more with adding noise only to the worst affected channels. I never realised that a simple thing such as a grad would cause me so much grief! And, it was a grey grad that caused me most grief; the coloured grads are not as affected (on screen and printing).

Thanks again...you have been a big help.

Craig.