Gradient riddle

[uniguide]

Hi all,

Here's my problem, check this out, iI BET it happened to you too...

I have a 30x40" image, drum scanned looks great and all... the gradients looks great, smooth transitions between colors.. yada yada...
BUTTTTTTT (bigger than J-lo's)
when i add a new layer, than add a gardient to it - it looks really bad,
the transition is not smooth at all, u can see the levels of tranparency, they look very rough and not-clean-lookin gradient.
I attached a sample, so you could see what im talking about
The enlarged box is a zoom so you could see how bad it looks.

Check it out, and let me know if it happened to you before, and how you bypassed this problem.

* the file size is 30x40" 300DPI.

Thanks a million for the genious who solve this riddle!!!
Z

[Ziaphra]

No help offered here...just wanted to say that is one gorgeous photo!

[Photo678]

try to apply a slight gaussian blur to the gradient, and then add a smidge of noise/grain to it to blend it in a bit better.

as a second option, the gradient tool in illustrator is far more advanced than in photoshop.....thus, as an option make one in illustrator save as eps to keep it vector based, and open in PS, and place as your BG

[Cameraken]

Hi Uniguide

Welcome to Retouch Pro

I think I ran into a similar problem here (post 45)

http://www.retouchpro.com/forums/sho...7&page=3&pp=15


The answer, supplied by Stroker on the next page, was to set smoothness to zero


If that does not help then you could always give the gradient a blur as Photo678 has suggested.

Ken

[Cameraken]

This is interesting

Attached are the histograms for black to white gradients

Setting smoothness to zero does help but it appears that Gaussian blur is making this worse.

Any ideas anyone?


Ken.

[recrisp]

It's actually a horizontal banding, not verticle, that is, if I am seeing what y'all are...

Anyway, "banding" has been the bane of the scanned or digital image since I can remember... The most common attack on it is to use Gaussian Blur, but like what has been said, it will make it even worse. The idea behind this is weird, but it works, and it's kind'a like 'fighting fire with fire'. Using the Noise is the best I have seen, and as far as I know, they still use that method in the professional world of retouching. Personally, each image is different, and although I will always use the Noise, I do sometimes use a little Gaussian Blur to smooth it out afterwards, but VERY LITTLE. Like I said, they're all different, so it may not work on every image.
One thing too, I know that it appears that putting noise into a sky or something will make it look worse, but the thought process on that is, it makes it 'appear' smoother, by filling in the sharp jumps from the stair-step look we already see, and when printed, the noise won't look nowhere near as bad as one might think, and isn't noticeable.

Randy

[Cameraken]

Hi Randy.

I tried adding noise but it did not help the histogram. (I do agree we are talking about horizontal banding though)

This is what I mean.
Attached is a gradient made with FilterMeister

Here is the simple code
%ffp
R, G, B: x
A: a

Take a look at the histogram. It is a perfect straight line, as expected. Why can’t Photoshop do this?

Ken.

[Littlecoo]

Yeah Ken it is a bit of a pain I agree, I often have to set up gradients and the like in Illustrator first as vector objects, if I go to print straight from Illustrator the gradients turn out well, but if I select-copy-paste to PS2 as a vector smart object... still get banding issues with gradients however...annoying!

[Doug Nelson]

Blurring will tend to make banding worse (it's counterintuitive, but excessive smoothness is what causes banding). Try adding noise before doing anything else.

Also, verify that the banding is in the file, not just on your screen. Zoom in and use the eyedropper and info palette to see if it's an actual jump or if it just displays as one.

[recrisp]

Ken,

I haven't checked this with a Histogram, and really, I never have. I always use my eye to get rid of the problem. I do see what you mean though. There have only been a couple of times that I wasn't satisfied using the Noise method, and since I am no longer involved in color-correction as my job, I am not in the know of new programs or maybe methods that can fix this.
99 times out of a 100 though, I have used Noise to fix it, and sometimes I will use a slight amount of Gaussian Blur to knock the harshness off. (Not enough to bring back the banding, of course)
I use Gaussian Noise, Not Uniform, if that would make a difference...

To clarify, I am talking about Photoshop, I don't use any other program to fix these types of things.

I don't know, I'd be interested in seeing how this comes out.

<Z Wrote>
"when i add a new layer, than add a gardient to it - it looks really bad,
the transition is not smooth at all, u can see the levels of tranparency, they look very rough and not-clean-lookin gradient."

One thing, and it's probably not this, but possibly "Z" changed the mode on the gradient, but didn't say.

Randy

[Cameraken]

Thanks for the replies Doug and Randy.

It does appear that adding noise is the accepted solution.
I have attached the histograms of a black to whites gradient (smoothness = 0)
The second one has 3% gaussian monochromatic noise added.

This histogram does not look that much better but it sure does help the banding.


Apologies to Uniguide for the hijack of your thread but I hope this has helped.

Ken.

[lkroll]

As long as the transistions ...

...are not abrupt, I've found that using Xero's fuzzifier adds just the right mix of noise and blur to blend gradients fantastic. I use this filter a lot for sky gradients.

[uniguide]

GUYS &amp; GRRLS - UR THE BEST

Adding noise solved most of the problem.
You guys are the best, its so good to know that there are people who are willing to contribute their knowledge to help others.
I am doing the same, aways willing to help others, if i can.
Together we make an awesome community.

LOVE YOU ALL!
XOXOXOXOXOXOXO
Zohar L.