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banding in my gradients

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  #1  
Old 04-01-2010, 04:35 AM
kkamin kkamin is offline
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banding in my gradients

On my monitor, I can see banding in the radial gradient on the background. I created this in Photoshop. Why is this happening? Is there anyway to avoid this?
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Old 04-01-2010, 10:53 AM
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mistermonday mistermonday is offline
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Re: banding in my gradients

To avoid the banding, work in 16 bit mode. That will either completely or mostly prevent it from occurring. To mitigate its effects on an existing image, you can add a small amount of noise (Filter>Noise>Add Noise)
Regards, Murray
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Old 04-01-2010, 11:51 AM
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garibaldi garibaldi is offline
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Re: banding in my gradients

make sure dither is checked. 16 bit can help sometimes. it also depends where your putting the image, is it going on web, or print. also the quality of your display. try hard proofing it and see if the banding remains
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Old 04-01-2010, 12:18 PM
kkamin kkamin is offline
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Re: banding in my gradients

Quote:
Originally Posted by mistermonday View Post
To avoid the banding, work in 16 bit mode. That will either completely or mostly prevent it from occurring. To mitigate its effects on an existing image, you can add a small amount of noise (Filter>Noise>Add Noise)
Regards, Murray
But wouldn't it occur later when I convert from 16-bit to 8-bit?
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Old 04-01-2010, 02:36 PM
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garibaldi garibaldi is offline
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Re: banding in my gradients

I had an issue a while back with banding in my images. turned out to be a faulty monitor profile that was exaggerating the issue. None the less, Here was some tips I had gotten from NAPP help desk.


It's not unusual for a gradient or soft transition to result in banding. Here is an explanation of banding that should help you understand what's going on:

Banding results when too few variations in color are spread over too large an area. A gradient, glow, shadow, or other gentle transition in color actually consists of a number of very similar (but different) colors aligned next to each other. The differences in those colors, as you know, are due to differing amounts of the component colors. Each actual color in the gradient is referred to as a "step." How many steps you have over a given distance determines how large each step will be. 100 variations in color over 100 pixels makes each step one pixel wide. Spread that same gradient over a distance of 1,000 pixels and each step is 10 pixels wide.

Let's take the example of a gradient that goes from pale rose to white. If we define pink as RGB 255/216/236 and white as RGB 255/255/255, we have very few variations in color with which to work. There are no variations in red. There are 40 variations of green (216, 217, 218,...255.). There are 20 variations in blue (236, 237, 238,...255). The blue channel has 20 steps, the green channel has 40 steps. If we spread that gradient over 800 pixels, the steps for the channels are 20 and 40 pixels wide. The edge of each step is a transition between two shades of blue or two shades of green. And in this unfortunate example, every transition of blue coincides with a transition of green, making the line between those two steps even more apparent.


The best way to reduce the effect of banding is to add noise. Here is the method I recommend:
-Add a new blank layer above the other layer(s).
-Fill the new layer with 50% gray.
-Change the blend mode of the gray layer to Overlay. At this point the gray will not be visible.
-Make sure the gray layer is active in the Layers palette and go to Filter > Noise > Add Noise.
-In the Add Noise dialog, choose Gaussian for the Distribution and make sure the Monochromatic box is checked.
-Start with the slider all the way to the left. Move it in small increments to the right, just until the banding disappears. The noise should barely be noticeable on the rest of your image, but if you want to get rid of the noise in the non-banding areas, you can use a layer mask.

If that doesn't work, here are some things that can be done to minimize banding:
--Check the Dither box in the Options Bar before dragging the gradient.
--Shorten the gradient, keeping the same area. If the gradient goes from blue to red, consider dragging the gradient tool over only the middle third of the length. That gives you one-third blue, one-third transition (gradient), one-third red.
--Shorten the area, keeping the same gradient. Use the same gradient in a smaller area, leaving the rest of the area for another design element or as white.
--Check the number of steps for each component color and make sure that the edges of the steps don't coincide. In some cases, a slight change in one component color can stagger the steps enough to disguise the banding.

Hope that helps.

Thanks for your question, and best of luck!

Jeanne
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Old 04-02-2010, 03:24 AM
Quantum3 Quantum3 is offline
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Re: banding in my gradients

1) Banding is usually seen in the screen, only.
2) Banding is usually seen in 8 bits files, specially in monochromatic images.
3) Banding is usually seen when the image is not at 100% of its size.
4) Banding is usually seen in compressed files, such as JPEG.

1) Print the image and look for the banding, you will find an smooth transition instead banding, considering that an ink printer is not able to print nice transitions but it will work enough for this. Also, consider buying a 16 bits monitor.
2) Always work in 16 bits to avoid banding a little. Don't know too much about this but an 8 bits file has only 256 values per channel, resulting in the shadows, no more than 32 to 64 tones, which means that our eye is capable to see the lack of tones in the gradient.
3) Always check your image at its full size in order to see if there is banding. Usually, when the image is not at 100% happens that the image pixels doesn't match the screen pixels so perfectly like at 100%, and the image is quite degraded by the monitor.
4) Save JPEG quality 10-12 or avoid JPEG and save in PNG or PSD/TIFF.
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