isoimap: Plot ellipses superposed over the gray-scale image display.

Package: isophote

Usage

isoimap image table

Description

The 'isoimap' task displays the original image in the gray-scale image display, and superposes ellipses on it. Ellipse data is taken from a table created by the 'ellipse' task.

This task is a script which calls the tasks 'tsort' and 'trebin' in the 'ttools' package. These tasks create a temporary table with an interpolated version of the original input table. This temporary table is then fed to the hidden task 'map', which creates a set of temporary files containing coordinates of ellipse points. The 'images.tv.display' task is then invoked to load the image display with the original image, and finally the 'stplot.sgraph' task uses the temporary ellipse point files to draw the ellipses.

The semi-major axis length interval to be plotted is specified by the parameters 'minsma' and 'maxsma'. If the 'fulltable' parameter is set to 'yes', the full range of semi-major axis lengths available in the table is used instead. Care must be taken with parameters 'minsma' and 'maxsma', because the 'trebin' task can also extrapolate from the original data, and meaningless results could be generated in some cases. Linear interpolation is used. The 'nlevels' parameter specifies the number of ellipses to be plotted, up to 10.

Parameters available in the 'display' task can be set before running this task so that gray-scale manipulation can be controlled. There are, however, limitations in the graphics interface so the task assumes that the 'fill' parameter is set to "yes". This also works only when the image display is square (i.e., it has an aspect ratio of 1.0).

Packages 'ttools', 'stplot', 'plot', 'images' and 'tv' must be loaded before using this task.

Parameters

image [file name]: Input image to be displayed.

table [file name]: Table containing the results of isophotometry analysis (i.e., the table produced by 'ellipse').

(fulltable = "yes") [boolean]: Use full range of semi-major axis from table?

(minsma = 1.0) [real, min=0.0]: Minimum semi-major axis to be plotted.

(maxsma = 1.0) [real, min=1.0]: Maximum semi-major axis to be plotted.

(nlevels = 3) [integer, min=2, max=10]: Number of ellipses.

(color = "r") [string, allowed values: r | g | b | w | y]: Graphics overlay color (colors are red, green, blue, white, or yellow).

(frame = 1) [int, min=1, max=4]: Display frame to be loaded.

Examples

1. Draw three ellipses taken from an image called 'image' and a table 'table'. Minimum and maximum are 10.0 and 100.0, respectively.

st> isoimap  image table fulltable=no amin=10. amax=100. nlevels=3

Bugs

Graphics overlay may lack precision when using image sections with stepping, due to numerical truncation effects.

References

This task was written by I.Busko