scale_image_crate

Synopsis

Scale the pixel values in an IMAGE crate.

scale_image_crate(crate, scaling="arcsinh")

Description

This routines applies a scaling function to the pixel values stored in an image crate.

Scaling routines

WARNING

This routine modifies the data in the crate; it does not return a modified copy. There is no way to undo the changes made by this routine other than to use read_file() to re-read in the original data.

Loading the routine

The routine can be loaded into Python by saying:

from crates_contrib.utils import *

Writing the data out to file

The write_file() command can be used to write the scaled data out to a new file.

Examples

Example 1

>>> cr = read_file("img.fits")
>>> scale_image_crate(cr)

Here we use the default scaling method (arcsinh) to scale the data.

Example 2

>>> r = read_file("evt2.fits[energy=500:1500][bin sky=::4]")
>>> g = read_file("evt2.fits[energy=1500:3500][bin sky=::4]")
>>> b = read_file("evt2.fits[energy=3500:7000][bin sky=::4]")
>>> scale_image_crate(r)
>>> scale_image_crate(g)
>>> scale_image_crate(b)

Here we use the default scaling method (arcsinh) to scale the "soft", "medium", and "hard" bands (these energy ranges are aribtrarily chosen for this example).

Example 3

>>> cr = read_file("img.fits")
>>> scale_image_crate(cr, "log")
>>> write_file(cr, "img.scaled.fits")

A new file is created - called img.scaled.fits - which contains the natural logarithm of the pixel values.

Bugs

See the bug pages on the CIAO website for an up-to-date listing of known bugs.

Refer to the CIAO bug pages for an up-to-date listing of known issues.

See Also

contrib

make_image_crate, make_table_crate, smooth_image_crate, write_arrays, write_columns

crates

add_col, add_key, add_piximg, delete_col, delete_key, delete_piximg, read_file, read_pha, read_rmf, write_file, write_pha, write_rmf