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2 Messages

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134 Points

Sun, Jul 11, 2021 9:58 AM

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Gradient Tool "Dither" Introduces Saturation with Greyscale Values

When turning "dither" on for the gradient tool, I would expect the dither to use various values of the colour that I am using, rather than introducing other colours. I work a lot with just 0% Saturation Values, and I was colour-picking odd 1% saturation colours from my canvas. I eventually figured out that it was the dithering for the gradient tool causing this.

Totally understandable if some people want the option of having colour noise dithered throughout their gradients, but this should be a separate option. I should be able to use the gradient tool, with dithering, and retain 100% purity in whatever colour I am using right? Dithering can work just as well using value only. If I'm mistaken, that's all right, this just seems like a bug, oversight, or missing checkbox.

Accepted Solution

Champion

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1.9K Messages

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28K Points

5 m ago

I still don't understand why this noise isn't simply applied to the "lightness" of each pixel but rather the saturation and hue as well.

There is no Lightness Channel in RGB images, so the Dither (effectively Noise) cannot be applied to that but is applied to all three Channels. 

As there are workarounds by which one can achieve the »neutral« result it would appear to be possible to add it it in the Gradient functionality but it would increase complexity (at least a little) and could adversely affect effectiveness. 

Champion

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1.9K Messages

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28K Points

5 m ago

I should be able to use the gradient tool, with dithering, and retain 100% purity in whatever colour I am using right?

It seems perfectly reasonable for the noise in RGB or CMYK files to affect all channels.

Please post screenshots (taken at least at View > 100%) to illustrate your claim. 

You may want to start using Gradient Layers instead of the Gradient Tool. 

That way you could just add a Clipping Masked Adjustment Layer to eliminate the Saturation variance. 

Or use a Pattern Layer with an appropriate Blend Mode (Linear Light for example) and don’t apply Noise to the Gradient itself. 

2 Messages

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134 Points

5 m ago

Hi Christoph, I'm not 100% sure I'm following. I never applied any noise, it seems the dithering IS the noise. And yes, I'm sure there are plenty of workarounds, and to be frank, I don't even need dithering for most of what I do. I simply noticed that this option was bringing in saturation even on greyscale values, which I find odd. The way I use my gradient tool to paint I can simply turn this off (now that I know about it) and never have this issue again.

Here's an example. White background, I grabbed a 50% grey with no saturation whatsoever, and then I made two gradients next to each other, one with dithering, one without. The banding is slightly noticeable in the non-dithered version, but not a big deal. Then I added an adjustment layer simply bringing the saturation of both gradients up. You can see, the left gradient is not greyscale, it has a colour noise applied, I assume to act as dithering. Since desaturating this gradient all the way keeps the smooth "dithered" gradient, that means that the colour variation is unnecessary to achieve this blending, it's purely based on the value variation. This was causing me issues while colour-picking since I was no longer getting greyscale values, but odd 1% saturation colours. If this is the intended effect, then I have learned something today, I just didn't realize that dithering would "pollute" my values/colours. I still don't understand why this noise isn't simply applied to the "lightness" of each pixel but rather the saturation and hue as well. No big deal, just noticed it and wanted to point it out in case it can be remedied. :-)