imgets: Return the value of an image header parameter as a string

Package: imutil

Usage

imgets image param

Parameters

image

Name of the image to be accessed.

param

Name of the parameter whose value is to be returned.

value = ""

The value of the parameter, returned as a string.

Description

The value of the parameter param of the image image is returned as a string in the output parameter value. The CL type coercion functions int and real may be used to decode the returned value as an integer or floating point value. Both standard image header parameters and special application or instrument dependent parameters may be accessed. If the parameter cannot be found a warning message is printed and the value "0" is returned. Parameter names are case sensitive.

The following standard image header parameters may be accessed with imgets:

i_pixtype                       pixel type (short, real, etc.)
i_naxis                         number of dimensions
i_naxis[1-7]                    length of the axes (x=1,y=2)
i_minpixval                     minimum pixel value or INDEF
i_maxpixval                     maximum pixel value or INDEF
i_title                         image title string
i_pixfile                       pixel storage file name

This task is most useful for image parameter access from within CL scripts. The task imheader is more useful for just looking at the image header parameters.

Examples

1. Fetch the instrument parameter "HA" (hour angle) from the image header of the image "nite1.1001", and compute and print the hour angle in degrees:

cl> imgets nite1.1001 HA
cl> = real(imgets.value) * 15.0
42.79335

2. Print the number of pixels per line in the same image.

cl> imgets nite1.1001 i_naxis1
cl> = int(imgets.value)
1024

See also

imheader, hedit, hselect