Retinex algorithm

iarga · **Posted:** Tue Sep 13, 2016 10:43 am **(#1)**

David just made the Retinex-algorithm available in G'MIC: :clap

Retinex-algorithm

G'MIC>Colors>Retinex

So, refresh your filters in G'MIC please.

Ronounours · **Joined:** Jan 03, 2011 **Posts:** 1656

Thanks for the info iarga

Rod · **Joined:** May 16, 2010 **Posts:** 14730 **Location:** USA

Cool! Thanks folks.

lylejk · **Joined:** Sep 24, 2010 **Posts:** 12536

Nice; seems to give cleaner results than GIMP's Retinex preset too (not showing). Thanks for the heads up, iarga and thanks for the new preset, David.

Issabella · **Posted:** Tue Sep 13, 2016 2:32 pm **(#5)**

Thank you so much David. It'll help me a lot to get good results. Iarga, nice you saw it so quick. :tyspin

dinasset · **Posted:** Tue Sep 13, 2016 11:11 pm **(#6)**

thanks!
first test:

source:

Attachment:

pexels-photo-119974-large.jpeg.jpg [ 97.33 KiB | Viewed 3228 times ]

- created a new layer using GMIC retinex
- set mode to Dodge

outcome:

Attachment:

pexels-photo-119974.GMICretinexDODGE.jpg [ 192.78 KiB | Viewed 3228 times ]

Issabella · **Posted:** Wed Sep 14, 2016 2:26 am **(#7)**

I like that result, Dinasset. Did you apply default settings?

dinasset · **Posted:** Wed Sep 14, 2016 3:26 am **(#8)**

yes, defaults

Ronounours · **Joined:** Jan 03, 2011 **Posts:** 1656

I've added a new slider Regularization to be able to get rid of bloc artefacts appearing sometimes after applying the Retinex filter (usually in very dark & quantized regions). The regularization is based on guided-image filtering, and it seems to work quite well ! (see animation below).

Attachment:

anim.gif [ 572.84 KiB | Viewed 3194 times ]

dinasset · **Posted:** Wed Sep 14, 2016 4:59 am **(#10)**

many thanks, David, useful addition indeed

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