I have been using the HSV noise tool in Gimp to add noise to an image to simulate a grainy film-like effect. Mostly it's been working nicely but there are a few areas where it is coming out incredibly uneven and blotchy. I am altering the value and holdness sliders only as I do not want any hue or saturation noise. Holdness is generally left on the lowest setting. Increasing it obscures the ugly areas, but tones down the noise image-wide so I have to increase the value slider accordingly, bringing it back... Any idea how I can prevent this? I could create a second layer with less noise and painstakingly layer-mask the whole image if needed, but I was hoping someone would know a way to prevent the problem happening in the first place. A before-after example is shown below, value slider turned right up to highlight the effect.
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Problems adding noise
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ianp5a
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Hmm. Can't help with HSV noise. Did you try "Add film grain" on the Noise menu?
Also try the different "Noise types" (Gaussian/Poisson...) in G'MIC's "Degradations - Noise [additive]" feature.
(It's worth installing GMIC if you haven't already got it.)
Personally I'd go the separate layer overlay route. And with "Add film grain", it creates new layers, that you can mess with afterwards.
This was done with GMIC, Noise [additive]+ Gaussian + Value Channel, then a bit of slider.
View attachment 25908
Also try the different "Noise types" (Gaussian/Poisson...) in G'MIC's "Degradations - Noise [additive]" feature.
(It's worth installing GMIC if you haven't already got it.)
Personally I'd go the separate layer overlay route. And with "Add film grain", it creates new layers, that you can mess with afterwards.
This was done with GMIC, Noise [additive]+ Gaussian + Value Channel, then a bit of slider.
View attachment 25908
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swanseamale47
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I've not used the tool you are referring to, but does it have any options ? I use imagenomic realgrain for the odd occasion I need noise.
ianp5a
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You can also download a script called Film Grain that is similar to HSV noise. http://registry.gimp.org/node/8108 But with different options.
But you still should install G'MIC anyway for it's sheer variety of amazing options. Such as the foreground extraction interactive tool.
But you still should install G'MIC anyway for it's sheer variety of amazing options. Such as the foreground extraction interactive tool.
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My current version of gimp doesn't have a film grain function, so I might try G'MIC or the film grain plug in. Thanks.
Do either plug in give an option to make noise/grain bigger? I understand that HSV noise adjusts each pixel with a degree of randomness, but with a 16 megapixel image the effect is barely visible in a small image or print. Besides resizing the image before adding noise, is there another way I could go about it?
Do either plug in give an option to make noise/grain bigger? I understand that HSV noise adjusts each pixel with a degree of randomness, but with a 16 megapixel image the effect is barely visible in a small image or print. Besides resizing the image before adding noise, is there another way I could go about it?
ianp5a
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For a bigger grain size, if you created the effect on another layer, it would let you scale it independently.
If you haven't got the film grain command, I don't know why I do. I may have installed a general Package. If you install the latest version of Gimp, film grain might appear. Other than that G'MIC is your friend.
If you haven't got the film grain command, I don't know why I do. I may have installed a general Package. If you install the latest version of Gimp, film grain might appear. Other than that G'MIC is your friend.
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ianp5a
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I just realinsed I added the 'gimp-plugin-registry'. Which is a big set of plugins. Which is where I got Film Grain from. You should be able to add it directly from your app store/software manager. And here you can search for plugins such as film grain effects. "Heal selection" is another worthwhile plugin that cleverly replaces unwanted objects with the background.
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