Sent: 2010-07-28 08:02:21 UTC (over 1 year ago)

From: bobdobbs

Banding in gradient creation

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Hey guys.

I created an A4 sized canvas and made a black background layer.

On a new layer I wanted to create a large lighting effect that would use most
of the area of the canvas:

new transparent layer -> select fg to transparent radial gradient...

But I got banding.

I selected dithering, and still got banding.
I used a large, circular self-created circular fuzzy "lighting brush", and
tried to create the same target effect. Still got banding.

What's the solution to this?

--
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Sent: 2010-07-28 08:57:20 UTC (over 1 year ago)

From: Olivier Lecarme

Banding in gradient creation

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bobdobbs wrote:

> Hey guys.
>
> I created an A4 sized canvas and made a black background layer.
>
> On a new layer I wanted to create a large lighting effect that would use most
> of the area of the canvas:
>
> new transparent layer -> select fg to transparent radial gradient...
>
> But I got banding.
>
> I selected dithering, and still got banding.
> I used a large, circular self-created circular fuzzy "lighting brush", and
> tried to create the same target effect. Still got banding.
>
> What's the solution to this?

Is your image in indexed or RGB mode? Is your gradient monochrome? What
is its size?

Say you draw a monochrome gradient from back to white along 2560 pixels.
You only have 256 different colors, thus you get bands 10 pixels wide.
And dithering does not have a real effect in such a case.

--

Olivier Lecarme

Sent: 2010-07-28 09:14:52 UTC (over 1 year ago)

From: bobdobbs

Banding in gradient creation

permalink

>Say you draw a monochrome gradient from back to white along 2560 pixels.
>You only have 256 different colors, thus you get bands 10 pixels wide.
>And dithering does not have a real effect in such a case.

I'm in RGB mode. The image is 2480px wide and 2794px high.

Is there a way that I can create a smooth gradient?
Will switching to another colour mode help?

How can I work this out for myself in the future?

--
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Sent: 2010-07-28 10:00:50 UTC (over 1 year ago)

From: T?kés Ábel

Banding in gradient creation

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7/28/2010 9:14 AM keltezéssel, bob írta:
>> Say you draw a monochrome gradient from back to white along 2560 pixels.
>> You only have 256 different colors, thus you get bands 10 pixels wide.
>> And dithering does not have a real effect in such a case.
> I'm in RGB mode. The image is 2480px wide and 2794px high.
>
> Is there a way that I can create a smooth gradient?
> Will switching to another colour mode help?
>
> How can I work this out for myself in the future?
>
Hi,
I experience that a slight HSV or RGB noise can get rid of the bands. In
case of RGB noise, I see nice results with settings: Correlated noise
and Independent RGB switched off, and all channels set to 0.04.

However, of course, this adds a noise to your picture, so it can not
strictly be called smooth, but at least you don't have bands.

Abel

Sent: 2010-07-28 11:19:28 UTC (over 1 year ago)

From: Olivier Lecarme

Banding in gradient creation

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bob wrote:

> >Say you draw a monochrome gradient from black to white along 2560 pixels.
> >You only have 256 different colors, thus you get bands 10 pixels wide.
> >And dithering does not have a real effect in such a case.
>
> I'm in RGB mode. The image is 2480px wide and 2794px high.

I tried the same size with a gradient from black to white, and another
from red to green. In my opinion, the banding effect is not really
obvious, but maybe my sight is not as sharp as yours. Anyway, it is
still less obvious in the polychrome gradient.

> Is there a way that I can create a smooth gradient?
> Will switching to another colour mode help?

No, it would be worse.

> How can I work this out for myself in the future?

The only possible improvement would be to have 16-bit depth colors.
You'll have to wait for GIMP 3.0...

--

Olivier Lecarme

Sent: 2010-07-28 12:52:58 UTC (over 1 year ago)

From: waltonm@vqme.com

Banding in gradient creation

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If you've got banding, sometimes you can reduce it by applying a Gaussian
blur.

When I apply a simple light to dark gradient to a large area, my
experience is that some banding in inevitable. Blurring, noise, high or
low resolution, duplicate layers (moved, with blending modes and opacity)
. . . to some degree, it's always present. On the other hand, what appears
on the monitor may not be what you get in print, often prints show less
banding (I use an Epson 7600), and changing papers can make a slight
difference.

Walton

> I created an A4 sized canvas and made a black background layer.
>
> On a new layer I wanted to create a large lighting effect that would use
> most
> of the area of the canvas:
>
> new transparent layer -> select fg to transparent radial gradient...
>
> But I got banding.
>
> I selected dithering, and still got banding.
> I used a large, circular self-created circular fuzzy "lighting brush", and
> tried to create the same target effect. Still got banding.
>
> What's the solution to this?
>
>
> --
> bobdobbs (via www.gimpusers.com)
>

_______________________________________________
> Gimp-user mailing list
> Gimp-user@lists.XCF.Berkeley.EDU
> https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
>

Sent: 2010-07-29 00:49:42 UTC (over 1 year ago)

From: GSR - FR

Banding in gradient creation

permalink

Hi,
forums@gimpusers.com (2010-07-28 at 0914.52 +0200):
> >Say you draw a monochrome gradient from back to white along 2560 pixels.
> >You only have 256 different colors, thus you get bands 10 pixels wide.
> >And dithering does not have a real effect in such a case.
> I'm in RGB mode. The image is 2480px wide and 2794px high.

Really big image... if dithering is not helping, and some passes of
Spread filter are not hidding the problem, not much you can do
currently.

Also, are you sure your monitor is not the one giving you some extra
banding? Some are sold as 24 bit color, but are "18 plus tricks".

> Is there a way that I can create a smooth gradient?

Higher bit depth, which is not possible in GIMP for now.

GSR

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Sent: 2010-07-29 10:37:48 UTC (over 1 year ago)

From: bktheman34

Banding in gradient creation

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I think your problem may be more to do with your computer display settings.
Mines is on 32 bit - and I get no banding at all.

--
Bill (via www.gimpusers.com)
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Sent: 2010-07-30 08:26:04 UTC (over 1 year ago)

From: Miles Bader

Banding in gradient creation

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GSR - FR writes:
> Also, are you sure your monitor is not the one giving you some extra
> banding? Some are sold as 24 bit color, but are "18 plus tricks".

Probably _most_ monitors sold these days are "18 plus tricks"
(though the "tricks" these days seem to be a lot better than in the
past), with dodgy wording in the specs used to hide that fact from
all but the most determined buyers.

-Miles

--
The automobile has not merely taken over the street, it has dissolved the
living tissue of the city. Its appetite for space is absolutely insatiable;
moving and parked, it devours urban land, leaving the buildings as mere
islands of habitable space in a sea of dangerous and ugly traffic.
[James Marston Fitch, New York Times, 1 May 1960]

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Sent: 2010-08-25 08:35:05 UTC (over 1 year ago)

From: bobdobbs

Banding in gradient creation

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Hi Miles.

I'm afraid the technical details of bit-depths and monitor hardware are beyond
me.

However, when playing with inkscape I can create gradients that don't have
bands.

Also, when I'm viewing other peoples artwork online I don't get the bands.

I'm guessing that this might mean that the problem might not be my monitor,
but is more likely to be the technique that I'm using in gimp.
Could this be the case?

--
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Sent: 2010-08-25 17:16:57 UTC (over 1 year ago)

From: Josh Bialkowski

Banding in gradient creation

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You might want to check the color depth of your document. If it's
indexed color then the document may not be able to create smooth
gradients because their aren't enough colors in the pallet. You can tell
if this is the problem (on 2.6.8) by going through the menus to
image->mode->... If image->mode->indexed is selected then the document
is indexed color, and you should change it to image->mode->RGB.

On 08/25/2010 02:35 AM, bob wrote:
> Hi Miles.
>
> I'm afraid the technical details of bit-depths and monitor hardware are beyond
> me.
>
> However, when playing with inkscape I can create gradients that don't have
> bands.
>
> Also, when I'm viewing other peoples artwork online I don't get the bands.
>
> I'm guessing that this might mean that the problem might not be my monitor,
> but is more likely to be the technique that I'm using in gimp.
> Could this be the case?
>
>

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Sent: 2010-08-30 18:25:24 UTC (over 1 year ago)

From: Joerg Bergmann

Banding in gradient creation

permalink

Am 25.08.2010 08:35, schrieb bob:
> Hi Miles.
>
> I'm afraid the technical details of bit-depths and monitor hardware are beyond
> me.
>
> However, when playing with inkscape I can create gradients that don't have
> bands.
>
> Also, when I'm viewing other peoples artwork online I don't get the bands.
>
> I'm guessing that this might mean that the problem might not be my monitor,
> but is more likely to be the technique that I'm using in gimp.
> Could this be the case?
Here my two cents to that topic: photographic images don't show bands,
even with low bit-depths.
The reason is the noise within each photo. Bands can be avoided by
introducing controlled noise:
chose the least significant bit of each pixel's channels randomly
depending on the exact color of
the gradient at that point. But probably this must be a new feature
within GIMP...

Joerg