Information Technology Reference
In-Depth Information
Fig. 7.16
Image data
Height
Width
Bits per Pixel
hierarchy
2-D array
Height
Width
Bits per Pixel
Co-ordinate system
Time
2-D image
Height
Width
Bits per Pixel
Astronomical co-ordinate
system
Time -EPOCH
Bandpass
2-D
astronomical
image
Thus a 2-dimensional array is the most general; this can be specialised into a
2-dimanesional image with, for example, additional methods to get co-ordinate sys-
tems and the time the image was created. For the even more specialised astronomical
image one would add, for example the spectral bandpass of the instrument with
which the image was created.
7.8.2.1.2 Tables
A table consists of an ordered arrangement of rows and columns. This is a simplified
description of the most basic kind of table. Certain considerations follow from this
simplified description:
•
the term row has several common synonyms (e.g., record, k-tuple, n-tuple,
vector);
•
the term column has several common synonyms (e.g., field, parameter, property,
attribute);
•
column is usually identified by a name;
•
column name can consist of a word, phrase or a numerical index;
A hierarchy of table models is shown in Fig.
7.17
The elements of a table may be grouped, segmented, or arranged in many differ-
ent ways, and even nested recursively. Additionally, a table may include “metadata”
such as annotations, header, footer or other ancillary features.
