8 bit height conversion to 16 bit height

[enetheru]

Hey all,

I was working on a re-build of an old map and wanted to solve the banding issue for 8bit height images.

I worked out a technique that is better than a straight gaussian blurr, or convolution.

Separate out the image into separate frequency layers

start at the bottom(lower frequencies).

colour select the neutral colour with little to no threshold, and a bit of feathering.
then blurr the frequency above.

repeat till you reach the top..

You will still lose data, but what it does is blurr any high frequencies that arent surrounded by lower frequencies.. so a large plane with a high frequency line running through it(banding) gets eliminated.

[Beherith]

In Photoshop, this is called surface blur. Works wonders.

[enetheru]

In Photoshop, this is called surface blur. Works wonders.

hmm after some googling it appears the gimp has a gmic plugin for "surface blurr" called bilateral blurr.. but i dont think that would work on 16bit images..

Ooh... Gimps back end GEGL has a bilateral blur filter that isnt exposed directly in the filters menu but is under GEGL operation.. ok testing ...

[enetheru]

the bilateral blur compares favourably to my custom method definitely takes less time. but the results didn't seem as nice on comparison when i tested it on a mesh. still 1000% better than gaussian blurr.

[PicassoCT]

protip for recreating details in photoshop- save the original picture as a grey pattern..

blur it up
use bevell and emboss - your greyscale detailtexture for recreating the surface detail.. (even more pro use colourdoge with a slight suncolour)

Hit Hard Light voila

[smoth]

never use the blur tool, it adds noise.