Bin, Block, Zoom

ds9 works with both FITS binary tables, ie Event files, as well as images.

When ds9 reads an event file, it automatically bins the table into an image based on the Bin parameters.

Users can Zoom or Block images.


Data

ACT J0102-4915, OBS_ID 14022

download_chandra_obsid 14022 evt2
In [1]:
cd Basics; 
ds9 acisf14022N001_evt2.fits -scale log -pan to 3760 4290 physical -bin factor 2 & 
sleep 5
[1] 26218

Bin

Only applies to Event files (tables).

In [2]:
xpaset -p ds9 bin factor 8 

import -window "SAOImage ds9" ds9_02_bbz_01.png 
display < ds9_02_bbz_01.png

In [3]:
xpaset -p ds9 bin factor 0.5

import -window "SAOImage ds9" ds9_02_bbz_02.png 
display < ds9_02_bbz_02.png


Zoom

Applies to image or table. Resamples image array, ie Zoom by 2, displays each row & column twice. Zoom by 0.5 only displays every other row and column.

In [4]:
xpaset -p ds9 bin factor 1
xpaset -p ds9 zoom to 8

import -window "SAOImage ds9" ds9_02_bbz_03.png 
display < ds9_02_bbz_03.png

In [5]:
xpaset -p ds9 zoom to 0.5

import -window "SAOImage ds9" ds9_02_bbz_04.png 

display < ds9_02_bbz_04.png


Block

Applies to images & tables. Combines pixel pixel values.

Block by 2, sums (or averages) pixels in 2x2 grid. Block by 0.5 leaves 1-pixel gap between pixels.

In [6]:
xpaset -p ds9 zoom to 1
xpaset -p ds9 block to 8

import -window "SAOImage ds9"  ds9_02_bbz_05.png 
display < ds9_02_bbz_05.png

In [7]:
xpaset -p ds9 block to 0.5

import -window "SAOImage ds9" ds9_02_bbz_06.png 
display < ds9_02_bbz_06.png

In [8]:
xpaset -p ds9 quit
[1]+  Done                    ds9 acisf14022N001_evt2.fits -scale log -pan to 3760 4290 physical -bin factor 2
In [ ]: