Banding on gradients

[shellby]

Does anyone have any other ideas for combating banding. Often I have to recreate backgrounds for product shots. Usually there would be a solid colour with a white glow created on top of this using a radial gradient.

Another way of creating the glow is to draw a circle, then feather it at about 200 and full with white.

Adding noise on a 50% grey layer set to soflight helps a bit, but if you look through the channels you can still see banding. I usually add noise to the softlight layer at about 6 and then lower the opacity of the layer and apply the noise only to the glow.

I don't really want to be adding more and more noise because this starts looking ugly on the print.

The printer is an Epsom Sherper Agfa.

Thanks

[Cameraken]

Hi Shellby.

This thread may help.
http://www.retouchpro.com/forums/inp...nt-riddle.html


Ken.

[Jerryb]

hi,
First I am literally novice with photoshop and just a little above knowing about graphics... smile..

on banding I think it's important to know what causes and then be able if possible prevent them occurring...

I have found what causes banding with me, and lot of time it depends on the photograph how many shades and colors and areas of smooth color....
1. scanning..... especially if I scan at 24/32 bit and then display at 16 bit, the dithering action and alogrythems
2. when i change color modes... let say rgb>cymk I sometimes will see it
3. When using jpeg format, it lossy format to begin with and important shades and other data is lost, if compress too much I will defintitely see banding occur...

As far as repair once you have them I am not that good... this link address much better than i can what banding is and how to repair with photoshop.... and the repair is similar to what has been mentioned....
http://www.graphics.com/modules.php?...icle&artid=371

Originally Posted by shellby

Does anyone have any other ideas for combating banding. Often I have to recreate backgrounds for product shots. Usually there would be a solid colour with a white glow created on top of this using a radial gradient.

Another way of creating the glow is to draw a circle, then feather it at about 200 and full with white.

Adding noise on a 50% grey layer set to soflight helps a bit, but if you look through the channels you can still see banding. I usually add noise to the softlight layer at about 6 and then lower the opacity of the layer and apply the noise only to the glow.

I don't really want to be adding more and more noise because this starts looking ugly on the print.

The printer is an Epsom Sherper Agfa.

Thanks

[shellby]

I am not actually talking about banding in a jpg image.

I am creating a fresh background in Photoshop 300 dpi PSD
Solid colour with a white "glow" on top

[chromaticstyle]

i found a great way to combat banding. i had to recreate some laptop screens on an 8-bit 50MB TIFF. here is what i came up with.

convert the file to 16 bit. i know, it sounds crazy.

make your gradient as you plan on a new layer. add noise directly onto the layer, usually a large amount like 10%.

hit edit > fade noise, and knock it down to 0%. increment it in steps of 1% until the banding disappears, like magic! the noise should be almost invisible. you can convert back to 8 bit mode.

worked like a charm for me. good luck.

[Littlecoo]

I have noticed this alot in photoshop (gradient banding that is) if you have the means, you may want to try out vector gradients in Illustrator or the like...I am not certain how they turn out in print for you, but I had success with this, other than that I have only used the add gauss noise then blur trick and that was for large format output.

[OnAir]

Originally Posted by shellby

I am not actually talking about banding in a jpg image.

I am creating a fresh background in Photoshop 300 dpi PSD
Solid colour with a white "glow" on top

CMYK from the beginning, if your output is 4 color print, I think?

[shellby]

Yes I am working with CMYK images and outputting to a Sherper digital printer.

I will try the 16 bit conversion. Thanks.

Illustrator idea is a good one too, will need to test that to see how it prints.

Thanks guys!

[KR1156]

noise is usually the only thing that works for me,

we do offset printing mostly, some digital...and unless i add a ridiculous anmount of noise, it doesn't show up on the print. you never notice it.

[cricket1961]

Hey Shelby

I make all of my new gradients on a adjustment layer with dither on. I seem to have better luck than when using any kind of a feather or blur.
Also, when really desperate and I feel that I haven't worked hard enough I usually create a crazy curve to reveal where the banding is in the image and use the softlight method to take out the banding.

Chris

[dvaught]

Create your gradation in an alpha channel. Add 2 pixel noise. Apply a curve to the channel pushing your lower left point to the right 2 and your upper right point to the left 2 (input 2 and 98 respecively) Make the channel into a selection. Create a new layer and fill selection with the color you want. No banding what so ever.

This is also the best way to create shadows that won't band. I start by creating my shadow in layers using only black. When it is how I like it I turn off all layers except my shadow layers. Duplicate my black channel and follow instructions above.

To check for banding you can add a solar curve as Chris pointed out. See attached PSD file. Turn on the solar curve to reveal banding. I did a simple gradation and a drop shadow for reference. If you want to change the color of the gradation or shadow, simply pixel lock the layer and fill with new color or paint in where desired.

Sample.
http://www.dvaught.com/downloads/Gradations.psd
If it downloads as "Gradations.psd.txt" just delete the ".txt" file extension and open with PS.