Rendering artifacts when using a filter

I’m experiencing rendering artifacts when using the Gimp’s filter ‘Lighting Effects…’. Is there a workaround, or will this be improved in 3.0 (or further releases)?



In Gimp terms it is an ancient plugin, well past its sell-by-date. The artefacts come from the bumpmapping using its own layer. For a flat-ish bevel try making your own bump-map something like shown in inset and then play with the material sliders.

Gimp 3 ? Lighting Effects might be improved, but as far as I can tell, the bump-map option is not working with 2.99.19

Try putting your image in 32-bit FP precision. This avoids round-off errors and makes bump-maps(*) cleaner:

Created with a 32-bit FP workflow:


Created with a 8-bit gamma workflow, note the circular artefacts that pop up


(*) And some other filters that require a lot of precision such as a displace map

This is one of the best examples I’ve seen so clearly demonstrating why using images in high bit-depth mode is beneficial. One can always reduce to 8-bit for final output if needed, but for the application of some filters high bit-depth is necessary (and if you’re a heavy G’Mic user, it uses high bit-depth).

Thanks Ofnuts!!

– “Happiness is the meaning and the purpose of life, the whole aim and end of human existence.” ― Aristotle

Great advice. Unfortunately, old plugins like lighting effects do not always work in high precision.


This filter is not working properly in the first place. When I try to run the filter, the bump map is not being recognized. I get an error message and have to press [Ctrl]+[Z], and then run the filter again [Ctrl]+[F]. Then the bump map is there alright. I think it’s a bug in 2.10.30. But I will try what you suggested.

Well, best of luck, as previously the plugin is in Gimp terms prehistoric. From the plugin browser, Authors: Tom Bech & Federico Mena Quintero Version 0.2.0, March 15 1998 and that was when a large image was 640x480 pix. Parts of the plugin have not really worked since Gimp 2.6. the environmental map ? and the bump-map function is sort of working but does bring up those error messages.

You asked about Gimp 3 I think some of those old plug-in/functions like lighting-effects and gfig will be consigned to the deprecated bin. IMHO a full-blown 3.0 release is still some time away but some functions can give a similar effect and also edited in-place.

As an example, you do not say what OS you use, this is a linux Gimp 2.99.19 appimage.

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I agree. This is a great example. I wonder what would have happened with 16-bit?