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Archive for October, 2007

A Temporary PC Speedup for Graphics Work

Wednesday, October 31st, 2007

Laptop
There are times when I have my laptop disconnected from the network and I want to do some serious graphics work. Because graphics software is very CPU intensive, I want my graphics program to have as little CPU competition as possible. This is especially true when I am working on very large images in Photoshop or running a render using one of my 3D applications, be it Lightwave, Mojoworld, or Bryce.

Now I could use the Windows Task Manager to go in and one by one shut down processes that I know aren’t needed. Or I could use the Windows XP System Services tool services.msc to accomplish the same thing.

There are a few problems with this approach. First I need to remember what processes to shut down each time. Being disconnected from the network allows me to shut down quite a few additional processes like antivirus, firewall, and other internet-related processes. On a typical Windows PC, this can be a rather lengthy list. And once I know what I want to shut down, I have to find each process in the list of processes and manually shut them down one by one. What a pain.

My solution was to automate the process. I had previously created a directory on my laptop called a_Utils which contained a variety of DOS batch programs I had written. One thing I did when I created this directory was to make sure that it was in the Windows Path environment variable – a variable that tells Windows where to look for programs. This variable can be set on Windows XP as follows:

  1. Right click the My Computer icon and select Properties
  2. Click on the tab labeled Advanced
  3. Click on the Environment Variables button
  4. In the System variables window, locate the variable Path and select it by clicking it once.
  5. With Path selected, click on the Edit button at the bottom of the window.
  6. In the Variable value field, go to the end of the field, add a semicolon if one is not already there and type in the full path to the directory that contains your batch file.
  7. Click the trail of OK buttons back to the System Properties window
  8. Click the OK button

In my directory a_Utils I created a DOS batch program file named !KillTasks.bat. This file consists of a list of taskkill commands. Taskkill is a Windows command line program that is used to terminate one or more tasks or processes which are identified by either their process ID or image name. I use the command in the following form:

taskkill /f /im ImageName

The parameters I specify are:

  • /f which tells Windows to “forcefully” terminate the process. In other words, don’t take no for an answer.
  • /im tells Taskkill that I am specifying the image name of the process to be terminated.
  • ImageName gives Taskkill the name of the process to terminate.

So far this has all been rather straight forward. Now the trick is in identifying what tasks or processes you can safely terminate. My method of doing this was to open Windows Task Manager and go to the Processes tab. Looking over the list of processes, the function of several was obvious and I knew whether or not it was a process that must run or a process I could kill. For others, I plugged the Image Name into a Google search in order to determine what the process does and whether or not I could kill it.

Following is an extract of what my !KillTasks.bat looks like. In this extract I am only including the commands for terminating my Nikon camera monitor and Copernic desktop search tool. The actual list is much longer.

taskkill /f /im NkbMonitor.exe
taskkill /f /im CopernicDesktopSearch.exe
pause

I close my program with the PAUSE command. This prevents the DOS window from closing until I press the Enter key, giving me the opportunity to look over the command output. This is just a personal preference on my part.

Now whenever I want to disconnect from the network and do some serious graphics work all I have to do is run my batch program. To make it really easy I created a shortcut to the program on my desktop. One double-click and my laptop is ready for some heavy duty graphics work.

Ad Astra, Jim

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Astronomers: Take the Sharing the Universe Survey

Wednesday, October 3rd, 2007
Are the Stars Out Tonight
Are the Stars Out Tonight?

I just got an e-mail in my JPL Solar System Ambassador Inbox about a new survey that is underway for amateur astronomers. Note that the survey must be done by Monday October 8. What is the survey about? To quote from the e-mail:

“Through funding from the National Science Foundation, the Astronomical Society of the Pacific (ASP) and the Institute for Learning Innovation (ILI) are conducting a national study to better understand the amateur astronomy community and the activities and mechanisms that promote astronomy education to the public… By completing this survey, you are eligible to enter into a drawing for one of five $50 gift certificates to Sky and Telescope’s online store.”

The survey is a part of a program titled “Sharing the Universe”. I just completed the survey myself. It is straight forward and there were no questions that anyone could consider an invasion of privacy. If before taking the survey you would like to know more, then visit the Astronomical Society of the Pacific’s Sharing the Universe page.

Again, the deadline is Monday October 8. The survey only takes a few minutes so why not take the survey right now. Take me to the Survey.

About the Picture

The picture used to illustrate this post, titled Are the Stars Out Tonight? is a small section of a starfield that I am working on in Photoshop. The starfield will serve as a background for an as yet to be determined foreground scene.

Ad Astra, Jim

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NASAView Limitations

Tuesday, October 2nd, 2007
NASAView JPEG vs GIF Comparison of a Mars Reconnaissance Orbiter HiRise image
NASAView JPEG vs GIF of a Mars Reconnaissance Orbiter HiRISE image

For those wanting to work with the raw data files returned by various NASA planetary missions the first order of business is to convert the data from its native PDS (Planetary Data System) IMG format into something usable by standard image processing software, like Adobe Photoshop. The NASA PDS Software Download site provides a variety of software packages for use in processing various NASA data products. For Windows users the only program available there for converting IMG files is NASAView. The most recent version of NASAView is 2.14 and was released in June 2007. Earlier versions of NASAView supported saving IMG files only as GIFs. Recent versions have included the option to save to JPEGs.

By design, GIF files are limited to 8 bits of color information per pixel. In the case of PDS IMG files, this means that each image is limited to a palette of 256 gray levels with 0 representing black and 255 representing white. Because the PDS IMG files from earlier missions contained only 8 bits of information per pixel, there was no data lost in the translation from IMG to GIF.

But what about when saving the IMG file as a JPEG. I do not know what the rationale was for adding the ability to save JPEGs. Perhaps so people could easily have an image that was more web friendly in terms of the file’s size. I strongly advise against ever saving an IMG file as a JPEG in NASAView. The reason is because of the JPEG compression. Unfortunately NASAView does not give the user any control over the level of compression. From what testing I have done, it appears that NASAView defaults to a quality setting of 75%. While this may be fine for dumping an image on the web, it fails when it comes to producing quality print images, especially if you want to enlarge the image.

To illustrate the impact of JPEG compression in NASAView take a look at the image at the top of this article. This is a 300% magnified view of a segment of a Mars Reconnaissance Orbiter HiRISE image. On the left is the JPEG version and on the right is the GIF version of the same area, only mirrored. The JPEG artifacts are obvious and take the form of square blocks. Of course there is a significant difference in file size. Whereas the GIF version is just about 7 megabytes, the JPEG version is just over 1 megabyte. Another differences between the JPEG and GIF versions are that the JPEG version is brighter than the GIF version.

In closing, my advice is that if you are using NASAView to convert IMG files to a standard graphic format file, never ever use the “Save JPEG” or “Save JPEG AS” options. If you need a JPEG version, then save your file as a GIF and use another pieces of software to do the conversion to JPEG so that you can control the amount of image compression used. Hopefully in the future a more robust version of NASAView will be released which offers Window’s users greater control on output file format and quality.
Ad Astra, Jim

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