Can I eliminate banding in transparency linear gradients?

[shokan]

I notice that all gradations, not just linear, show a regular banding pattern. In a linear transparency, I notice wide bands about 1/2" wide, with maybe 17 very small bands making up each of the wider ones. This banding would be difficult to get rid of by blurring in another program. By the time the fill was sufficiently evened by blurring, the edges'd be bad.

I want to use a Xara drawing as a heightfield model in a terrain application. These greyscale translations are very sensitive to even slight variations in shades, so that banding sure does show up in 3D the model.

[shokan]

I notice that all gradations, not just linear, show a regular banding pattern. In a linear transparency, I notice wide bands about 1/2" wide, with maybe 17 very small bands making up each of the wider ones. This banding would be difficult to get rid of by blurring in another program. By the time the fill was sufficiently evened by blurring, the edges'd be bad.

I want to use a Xara drawing as a heightfield model in a terrain application. These greyscale translations are very sensitive to even slight variations in shades, so that banding sure does show up in 3D the model.

[lau3]

Hi,

If you use a GIF, try setting the Dithering to "Error Difussion" (default is none). If you use PNG or BMP, bump yourself up to true color to eliminate the banding. Ig you keep PNG to 256 colors, the same as GIF, set Dithering to "Error Difussion". JPG does not have this but it chunks away data so it is "full of holes".

Milt

[shokan]

Do you mean set true color (highest setting) on my computer?

[Ross Macintosh]

Milt is refering to the settings when exporting (and not your graphics card settings although if it is set too low you'll see banding almost all the time).

I sure hope you'll post the results of your terrain generation Shokan. I like to play with Terragen but I've never tried importing a bitmap for use as the heightfield. I have wondered about what it would look like if that heightfield were just text -- I imagine a letter-shaped mountain could look pretty cool canyonized!

Regards, Ross

<a href=http://www.designstop.com/>DesignStop.Com</a>

[shokan]

I tried those things and the banding remains. But with blurring in P'shop and then using a type smooth tool in Amapi, I get a rounded off version. I will be working with Bryce 5 heightfield shortly. It should be better than Amapi, for several reasons.

[lau3]

Shokan,

A couple of questions:

1. Is your Palette set to "optimized"?

2. Also, how big a color gradient are you trying to create? That is, if you are trying a simple ramp from white to black over 1000 pixels, banding will probably happen regardless of dithering settings. That's because most bitmap are exported using 256 steps to create a gradient. If you do the math, you end up having to duplicate the same color over multiple pixels.

PNG or a full color bitmap should avoid this issue. Make sure your dpi settings are screen (96 dpi - Xara default) and your image is not huge (H x W). I've imported PNG's without banding into Bryce and 3D Studio Max without any issues.

Good Luck,

milt

[Squeaky]

I found I get banding when I export with CMYK preview turned on. Seems to work better when I turn it off though.

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