Java Image Preview Application V1.2

M. Dolensky, ST-ECF, Nov. 98

Follow this link for a NEWER version of JIPA!

How to use JIPA
How to install JIPA as an Application
New Features of JIPA V1.2
List of tested Environments
Web Browsers and Java Support
Related Publications
Feedback

How to use JIPA

There are several possibilities:

As an Applet (works with Netscape 4.04 or later, Internet Explorer 4, Hotjava).
For instance, JIPA is used to access preview FITS images of the HST archive.
Click here for an example.

This is how to include JIPA into your own web pages:



<APPLET codebase="/Your/Installation/Directory/" 

  code="JIPA.class" 

  name="JIPA" 

  archive="JIPAStartUp.jar,JIPABody.jar" 

  width=420

  height=406 

  align="middle">

<param name=cabbase value="JIPAStartUp.cab,JIPABody.cab">

<param name=fitsurl value="http://Your.Web.Server/Your/Data/Dir/jipa.dat">

<param name=mag value="1.0">

<param name=fliptb value="true">

<param name=eqflag value="true">

<param name=wantframe value="false">

<P>This page can only be viewed with a Java enabled browser.</P>

</APPLET>

As an Application.
Usage: java JIPA [wantframe fliptb eqflag mag [fitsurl]]
Click here for more about installing JIPA.

Command line arguments recognized by JIPA:

Parameter	Valid Range	Meaning
wantframe	True or False	Run appl. in separate frame
fliptb	True or False	Whether to flip the image top/bottom
eqflag	True or False	Turns histogram equalization on/off
mag	Real Number	Initial magnification
fitsurl	URL	file: or http: pointer to FITS file

On a UNIX terminal this translates into a command like this (assuming that file $HOME/tmp/jipa.dat does exist):
java JIPA true true true 1.0 file:$HOME/tmp/jipa.dat

As a Module of another Java Application.
Check out the publications for details about JIPA interfaces.

How to install JIPA as an Application

Install a JDK 1.1.x or JDK 1.2.x compliant Java Virtual Machine (JVM) if needed. Unfortunately, it is beyond the scope of this document to describe how to setup a JVM for a specific platform. In the ESO/ECF domain the Java environment is setup by issuing the following command on a Unix terminal (or adding it to the .tcshrc):
source /ecfsoft/java/aliases; jdk116
Download the JAR archives listed below. The Microsoft CABinet files are not required unless you plan to run your local installation through IE (Internet Explorer).

File Size

JIPAStartUp.jar 16 KB

JIPABody.jar 70 KB

Only when used with Internet Explorer

JIPAStartUp.cab 13 KB

JIPABody.cab 63 KB

Test Image (gziped FITS)

jipa.dat 74 KB
Let's assume the JAR files now reside in $HOME/bin/ on your local machine. Then the CLASSPATH needs to be set like this (again, for UNIX):
setenv CLASSPATH $HOME/bin/JIPAStartUp.jar:$HOME/bin/JIPABody.jar:$JAVA_HOME/lib/classes.zip
Test JIPA: Click here for help on running JIPA.

File	Size
JIPAStartUp.jar	16 KB
JIPABody.jar	70 KB
Only when used with Internet Explorer
JIPAStartUp.cab	13 KB
JIPABody.cab	63 KB
Test Image (gziped FITS)
jipa.dat	74 KB

New Features of JIPA V1.2

Panel for LUT manipulations.
Methods for inverting as well as flipping image in X and Y.
File loader dialog (in application context only).
Support for CABinet files for faster download with IE (Internet Explorer).
Automatic detection and support for gziped FITS as well as plain FITS files.
Enhanced GUI:
- Status bar to keep user informed.
- Merged zoom-, contrast- and color-widget.
- Work around for Scrollbar confusion among various JVMs.
- Scrollbars only appear on demand.
- Image is centered on display when it's smaller than canvas.
- Sculptured borders around panels.
- Option for immediate image update (without pressing Apply button).
'javadoc' manpage for all source modules with automatized update.
Handle multiple images in a row via StarView II interface.
Support for all standard FITS image formats, i.e. BITPIX is out of {8, 16, 32, -32, -64}.
Minor modifications to make JIPA JDK 1.2 compliant.
Introdcution of hotkeys for some menu items.

List of tested Environments

Platform/Environment	Java Virtual Machine or Java Component
Linux, Suse 5.1
Browser	NS 4.04, AppletViewer
MacOS
Browser	NS 4
Solaris 2.5
Browser	NS 4.04, NS 4.08, NS 4.5, IE 4, HotJava 1.1, AppletViewer
Stand-alone	JDK 1.1.4, JDK 1.1.6, JDK 1.2beta4
Instantiated	Starview II
Windows95
Browser	NS 4.04, IE 4
Stand-alone	JRE 1.1.4
Windows NT 4
Browser	NS 4

Web Browsers and Java Support

JVMs of Web Browsers often only support a subset of the standard Java classes and methods. Below is a list of features that NS 4.04 on Solaris is missing and for which a work around had to be found in each individual case:

Missing Entity	Work Around
Class java.awt.ScrollPane	Re-implement scrollable canvas class (>1000 lines of code!)
Method drawImage(10 args) in class java.awt.Graphics	Using simpler method drawImage(6 args) together with more complicated clipping strategy.
Method setSize in class java.awt.Component	Use deprecated method resize.
Method setLocation in class java.awt.Component	Catch exception and skip code when JVM doesn't support it.
Method setCursor in class java.awt.Component	Catch exception and skip code when JVM doesn't support it.
Method setCaretPosition in class java.awt.TextComponent	Catch exception and skip code when JVM doesn't support it.
Method setBlockIncrement in class java.awt.Scrollbar	Use deprecated method setPageIncrement.
Methods setHgap and setVgap in java.awt.GridLayout	Using layout manager GridBagLayout instead.
Method setEnabled in java.awt.MenuItem	Use deprecated methods enable and disable.
Constructor Checkbox(String, boolean) in class java.awt.Checkbox	Use Constructor Checkbox(0 args) and call methods setLabel and setState.
Constructor TextArea(String, int, int, int) in class java.awt.TextArea	Catch exception and use constructor TextArea(String, int, int) in that case.

IE 4 didn't support the 16-bit custom ColorModel for image display. Therefore pixel values are now mapped to 8-bit LUTs using class IndexColorModel.
Another problem concernes method getContentType in class java.net.URLConnection:
Method getContentType seems to determine the MIME type by looking at the file extension! This is clearly an unacceptable simplification. The method works, however, when the data are accessed through a CGI script that sets the mime type correctly.
Work Around: JIPA tries to find a match with a format specific magic number at the beginning of the input stream.

Related Publications

Reference	Download Article	Download Poster or Slides
Dolensky, M., Micol, A., Pirenne, 1998, HST Archive Services Implemented in Java, The ESO Messenger, 93, 23	HTML PostScript (1.6 M) Word97 (595 K)	-
Dolensky, M., 1998, Java Components and Design Patterns for Astronomy, Poster at Workshop on Observing Tools at Univ. of Maryland Conf. Center	-	HTML PostScript (6.0 M) PPT (377 K)
Dolensky, M., Mayhew, B., Kennedy, B., 1998, Design Study about Integration of Starview II and JIPA using advanced Java Mechanisms, ASP Conf. Ser., in press	-	HTML PostScript (6.7 M) PPT (1.0 M)

Feedback

We'd like to hear from you!
Although ST-ECF is lacking the resources for full featured user support we are constantly trying to accommodate with user requirements and to learn about software problems.

Send comments to <catalog@eso.org>.