Vast experience in LESSA incorporation into the various image processing systems and in developing of new user required tools is obtained. During about 20 years of the LESSA technology application several computer generations changed. LESSA worked on PDP 11/34 and special image processing hardware, such as IIS, SVIT, OKTET and DataTranslation.

Now several LESSA versions are available.

AZ_LESSA - the DOS version.
It is the most compact (1M) and the most worked-out, base version. It has worked since 1993 and the last variant AZ_LESSA3 was developed up to 2001.

ER_LESSA - Erdas Imagine module (distributed by the "DATA +" company).
ERDAS environment gives vast possibilities in interactive analysis, hard coping and incorporating LESSA tools in other technologies. Since 1999 two versions were developed.
In comparison with AZ_LESSA3 version ER_LESSA 2.0 has the following advantages

- stripes contrast thresholding;
- pseudocoloring range setting;
- precision lineament calculation;
- show lineaments according to the validity order.

WinLESSA 01 2002

This is version with friendly Windows interface. In comparison with ER_LESSA 2.0 version WinLessa 01 has the following advantages:
- calculate lineaments of arbitrary length,
- show lineaments in the arbitrary directional range, not in the fixed sectors;
- calculate global rose-diagram;
- calculate rose-diagrams in the user defined regions;
- save the workspace settings;
- save calculation parameters description for all saved images.

WinLESSA 02 2004

New capabilities if compare with WinLESSA 01 2002

- save results not only in raster but also I n vector (DXF) format;
- change analysis scale (size of the detected stripes);
- divide image into regions and get rose-diagrams in this blocks;
- mask image parts such as clouds, noise e.t.c.,
- calculate isolines for digital fields;
- calculate transparent images of the given range or extremums for digital fields;
- draw colored polylines to mark detected features;
- analyze data under cursor;
- add - delete digital fields;
- turn prepared in LESSA lineament scheme into stripes for rose-diagrams and fields calculation;
- set color and width for all vector data;
- automatically changes vector width to fit the current zoom;
- change palette for digital fields (number of steps, steps size calculation algorithms);
- combine vector layers;
- calculate more rose-diagrams parameters.

WinLESSA 2.1 2005

New capabilities if compare with WinLESSA 2.0 2004
It is the last version with the following new possibilities

- set geographical coordinates and save LESSA results in those coordinates;
- measure direction and distance on the screen;
- change block rose-diagrams size;
- use global normalization for block rose-diagrams;
- calculate global rose-diagram for lineaments;
- set digital field range for colorization automatically;
- select contrast for the multicolor palette;
- use the duetone green-brown palette.

WinLESSA 2.2 2006

It is the last version with the following new possibilities

- input DTM data in the GRD ASCII format;
- input geographical coordinates for the RAW format image;
- output greytone LESSA results in the GRD ASCII format;
- stripes densities calculation (instead of the stripes sum length);
- automatic elongation lines threshold calculation;
- output lineament rose in the text file.
But the main changes are in the lineament and stripes detection. First of all stripes direction detection in the greytone image was changed. Now stripe rose-diagrams are almost the same after the input image rotation.

This version can get all users of the versions 2.0 and 2.1.

WinLESSA 3.0 2007

Much more accurate stripes direction detection.
More accurate stripes distribution among long lineaments.

WinLESSA 3.1 2008

It's possible to distinguish ridge and valley stripes.

WinLESSA 3.2 2009

Short stripes filtration.

WinLESSA 3.3 2010

Long lineaments that cross image square fragments could be detected.

WinLESSA 3.3.1 2011

Several but small corrections and developments.

This version is free for all users of the versions 3.3.

WinLESSA 3.3.2 2012

One can visualise and save elongation direction.

WinLESSA 3.3.3 2022

Refinement of the analysis of schemes with rare lines, for example, hydronet  lines of separate orders.

This version is free for all users of the versions 3.3.

A FREE short version for the primary acquaintance and full documentation is available here.