Banding with gradient in spot colour

[K***@adobeforums.com]

I am using a Pantone colour to produce a two-colour job, with a gradient
from Reflex Blue down to paper. Banding is noticeable on screen in InDesign
and in the PDF. If I switch the stop colour from the Pantone to a CMYK
colour I can see the banding disappear.

I'm not used to working with spot colours. Is there anything I should have
taken into consideration for use with gradients?

k

[unknown]

How far does the gradient stretch? You've got to have enough room for
the color to change without going too far.

In short...I avoid doing this with spots because a lot of the tricks for
gradient smoothing can't be used.

Bob

[K***@adobeforums.com]

Thanks Bob. It's hard to say how far the gradient stretches because I
pulled, pushed and twisted the shape, and stroked it with the gradient tool
to get it to look as I want it.

Could it be that using a CMYK as a stop colour the gradient colour change
can be cheated visually by variations in the component colours, while with a
spot you've only got one colour to play with?

If that's it, then I'm going to have to go back and reassess how I use this
gradient - or print an extra colour and use the C and M mix.

k

[unknown]

You could try doing it in Photoshop as a grayscale TIF. Add some noise
there and try coloring in ID.

Worth a try.

Bob

[K***@adobeforums.com]

I'll have a fiddle. Thanks for help Bob.

k

[L***@adobeforums.com]

If you are dealing with only one spot color in your gradient, using a spot
should not present a problem. It should RIP and reproduce on paper exactly
the same as black. It is odd that you can actually see this on screen. I
can't recall ever seeing banding on screen in a non rastered image.

Larry

[G***@adobeforums.com]

I just tried this on my powerbook (i.e. LCD): three rectangles A4 high each having a gradient from paper to
25% HKS7
25% Cyan
14-7-0-0 CMYK

The last showed the worst banding in InDesign, all three showed comparable banding in Acrobat. I have no CRT around at the moment to check if this is just an LCD thing.

If you print on a PostScript 3 device you need not worry though. The banding should not be visible there.

[K***@adobeforums.com]

I am using LCDs, so perhaps that's a factor.

When using the spot colour the banding was obvious in the PDF at whole page
view. Zooming in, it remained.

If I used a zoomed in view in InDesign I could see the banding. When I
changed the stop colour in the gradient from Reflex blue to a CM mix the
banding instantly disappeared.

In the end I cheated. I wanted to keep the job down to two inks for economy,
but the colour of the blue wasn't critical. So I used 100C 25K which is a
long way from Reflex blue, but still met the spec for a 'bright blue'.

Switching to this mix as a stop colour instead of the Pantone killed the
banding, and I got a two-colour job with a bright blue and black, which was
the target.

As you say Gerald, if the banding was unlikely to be seen in print I had no
worries. But this way I took out some doubt.

I am guessing that the more inks you have in a gradient, the less obvious
banding is likely to be because superimposing gradients would blur the
banding effect.

Earlier Bob suggested making the gradient in Photoshop and colouring it. I
tried that with a 2400 ppi image but when I coloured it it looked just the
same as the InDesign gradient using the Pantone. That said, uncoloured in
just the black gradient I could still see banding, so maybe it's an LCD
thing more than anything else.

Thanks for your input gentlemen.

k

[Peggy]

I have a CRT and an LCD side-by-side, so if you'd like to send me the file,
I'd sure be interested in checking it out! Send the indd file to peggy at
pcdesktopdesign com. You can zip it if you're concerned about file
corruption.