help-smooth

Syntax_Smooth
Specify conditions for smoothing
HowTo Smooth Plain
HowTo Smooth Smart

NO SMOOTHING
- -smooth with a lowercase s..............Smoothing is disabled altogether
SMOOTHING
- -Smooth with an uppercase S.............Smoothing is enabled
  - Smooth_N................................Maximum radius N of smoothing kernel
  - N must be <==5
- -Smooth_ND............................ SmoothDeep=1
  - enable Smoothing of Optically_Deep_Waters_masked at 240
- Smooth_Nd.............................SmoothDeep=0
  - disable Smoothing of Optically_Deep_Waters_masked at 240
PLAIN SMOOTHING
- smart with a lowercase s, SmartSmoothing is disabled altogether
  - plain smoothing shall apply
SMART SMOOTHING
- Smart with a uppercase S...SmartSmoothing enabled
- Smart+............................Smart smoothing enabled, SmoothPlus=1:
  - Forces a minimum N=1 smoothing kernel for all bright shallow pixels
- Smart-.............................Smart smoothing disabled, SmoothPlus=0:
  - No smoothing of bright shallow pixels
Radiometric Noise (not compulsory, defaults to 1.00)
- Smart+1.25..........radiometric Noise is set at 1.25
- Smart+1.75..........radiometric Noise is set at 1.75
- noise must be set >=1.0
- for high noise level, increase from 1.00 up, see the results
- this is used in SmartSmoothing to specify the radius of the smart smoothing window

IMPORTANT NOTES

CUT LINE..........smoothing does not mix Flight_numbers: no smoothing across the mosaicking_cutline
WATER LINE.....smoothing does not mix shallow pixels and dryland pixels: no smoothing across the waterline
mSE....................smoothing does not mix mSE values of shallow pixels
- only pixels with same mSE values contribute to the smoothing of the current pixel

How to Smooh_Plain
Syntax Smooth

Plain smoothing applies a circular smoothing window
Radius of smoothing window is in the range from 1 to 5 pixels
- this achieves 3*3, 5*5, 7*7, 9*9 and 11*11 circular smoothing window
SmoothDeep
- enable argument D(d) to smooth optically deep waters if desired.
No smoothing across the waterline, No smoothing is applied over dry land
The radius of the smoothing window is written in image WR

How to Smooth_Smart
Syntax Smooth

Smart_Smoothing is needed over shallow areas
Dual purpose
- apply a wider smoothing geometric window to darker pixels, and vice versa in order to smooth more efficiently darker pixels
- select pixels within a limited radiance window for computing an averaged spectral radiance in an attempt to preserve edges
The Syntax_is -S(s)mooth_N/D(d)/S(s)mart+(-)
- S(s)mooth........enable(disable) Smoothing
- D(d)................. enable(disable) SmoothDeep to smooth optically deep waters if desired
- S(s)mart...........enable(disable) Smart_Smoothing
SmartPlus
- if SmartPlus is at +
  - above a certain brightness, all shallow pixels to be smoothed by a 3*3 window
- if SmartPlus is at -
  - no smoothing is applied to pixels above a certain brightness,
  - while smart-smoothing is applied to deeper/darker pixels
No smoothing across the waterline, No smoothing is applied over dry land

image_WR

Edge-preserving smoothing :

the N variable in -Smooth_N/D/Smart+ is used to customize the window radius for each shallow pixel as follows:

Can take values in the range of 1 to 5.
A rather complicated and confuse scheme, still under development: please experiment for yourself.
Within the resulting circular window, only pixels with a radiance inside a certain tolerance range shall contribute to the smoothing: others are bypassed.
- therefore, if a pixel is dark, only some dark pixels inside the circular smoothing window shall contribute to the computation of smoothed radiance for that pixel.
- therefore, if a pixel is bright, only some bright pixels inside the circular smoothing window shall contribute to the computation of smoothed radiance for that pixel.
As a result, sharp spatial contrast in the raw image shall hopefully remain sharp in the smoothed image.
It is necessary to experiment, in order to find a combination of the M and N variables that suits the image brightness and your particular expectations.