[X] My Assistant

[JohnVV]

--- Note to everyone ---
--- feel free to add your own favorite tool to "denoise"


On the Titan thread there is some discussion on "denoiseing "
machi commented that this program did not do well on the SAR data
http://bigwww.epfl.ch/algorithms/denoise/

as a few of you know by now i like a program called "G'Mic" ( was called GREYCstoration )

it works on floating point data natively this is very handy with ISIS3
cubeatt it to a raw with a detached header , clean it , and import it back into isis all in float format

machi was using the jpg'ed version of BIUQI03N158_D167_T044S01_V02.IMG with "PureDenoise"
to use the example on there page and the pds image

first the "example on the PureDenoise web site

the noisy one
http://bigwww.epfl.ch/algorithms/denoise/i...mple-noisy1.png
there "clean one
http://bigwww.epfl.ch/algorithms/denoise/i...xample-den1.png

first the " Hot pixel " removal
this is a good example for "salt and pepper" noise
--- from the "gmic -h ( help option )

-remove_hotpixels:
_mask_size>0, _threshold[%]>0

Remove hot pixels in selected images.
Default values: 'mask_size=3' and 'threshold=10%'.

CODE

gmic Example-noisy1.png -type float  -remove_hotpixels 3,3.0% -type uchar -o Example-less.png

the "-remove_hotpixels" tool needs a image to be in float format , hence the "-type float" BEFORE calling the tool
and setting the type to "uchar" ( 0 to 255 ) for saving to a 8 bit png

-- the gallery for the two above
http://imgbox.com/g/k6lYc1wU7l

the original is on the left and the hot pixel removed on the right

the image has a lot of dark area with very bright noise in it

---- the "denoise" option
-- from the "gmic -h " ( help option )

-denoise (+):
std_variation_s>=0,_std_variation_p>=0,_patch_size>=0,_lookup_size>=0,_smoothnes\
s,_fast_approx={ 0 | 1 }

Denoise selected images by non-local patch averaging.
Default values: 'std_variation_p=10', 'patch_size=5', 'lookup_size=6' and 'smoothness=1'.

contrasting this is the SAR t044 image
"BIUQI03N158_D167_T044S01_V02.IMG"

--- a crop to about the same area in the titan thread
this is in 32 bit float so Screen Shots --

CODE

pds2isis from=BIUQI03N158_D167_T044S01_V02.IMG to =BIUQI03N158_D167_T044S01_V02.cub
crop from=BIUQI03N158_D167_T044S01_V02.cub to=crop.cub sample=700 nsamples=1500 line=10000 nlines=3000
rotate from=crop.cub to=crop1.cub degrees=90
isis2raw from=crop1.cub to=crop1.raw omin=0.0

this is a bit better for the "denoise" filter
light gray on dark gray with a lot of noise in every tone range

CODE

gmic -type float crop1.raw,3000,1500  -denoise 9,9,3,4,1 -o crop1.denoise.tiff

the original is on the left and the denoised on the right

for a stronger denoise increase the lookup_size

CODE

gmic -type float crop1.raw,3000,1500  -denoise 9,9,3,9,1 -o crop1.denoise1.tiff

So 9 is a bit too much have a go with a look up size of 6

CODE

gmic -type float crop1.raw,3000,1500  -denoise 9,9,3,6,1 -o crop1.denoise1.tiff

for a bit more highs and lows drop the " std_variation_s and _std_variation_p"

CODE

gmic -type float crop1.raw,3000,1500  -denoise 3,3,3,6,1 -o crop1.denoise2.tiff

[Guest_alex_k_*]

A test of Fourier-based denoising - on an image that seems hopeless.

The source image is a damaged part of Luna 9 panorama 1:


After two-pass processing and wavelet denoising by GIMP we get the follows:


For verification I used appropriate part of Luna 9 panorama 3. The lander a little moved and tilted between panoramas, so I stretched the source image for comparison (maybe not very exact). The light source position is also changed between panoramas.

Details of the surface seem to be recovered properly.