One of the most frustrating aspects of taking pictures with a Kodak 4800 is its poor low light performance. The camera performs great when lots of light is available, but the lack of an “AF Illuminator” light makes taking pictures at night a real nightmare. In this article, I discuss a few alternatives to the problem, and how I solved it.

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Do you have something to hide? Of course you do! From PINs to business trade secrets, chances are there’s always something you need to keep private. This article describes how to create an encrypted fileystem under Linux using the AES cipher.

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Most digital cameras bundle some kind of software to create panoramas; a collection of pictures stitched together to form a single, seamless picture.

I was quite disappointed with Canon’s “stitching” software (came bundled with my S50). The software simply pastes the pictures together, creating a very heavy and noticeable blur at the edges, in a lame attempt to hide the seams. Dissatisfied with this solution, I googled around a bit until I found Hugin, an excellent GUI for the Panorama Tools.

Hugin can stitch your pictures perfectly, even if you didn’t use a tripod or if took them at different camera tilt angles (a common situation if you’re holding the camera with your hands). Unlike most software in its category, it uses “control points” to “glue” the images together and compensate for the differences in tilt.

Hugin does not try to hide the seams that connect your pictures. To make a perfect panorama, you’ll also need Enblend, which takes care of making the seams in your panorama invisible.

The results are indeed impressive, and the seams are very hard to locate. I recently took some pictures of mountain bike trails in Ocala, Florida, and joined them using Hugin+enblend to create this panorama.

For further reading, try this page, which explains in detail how to use Hugin and Enblend to make create a panorama from a set of images.

Keywords: camera, panorama, hugin, pano-tools, enblend, autopano, picture, canon, stitch

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Retrieving the current time under Unix is easy. Just use the date command:

$ date
Fri Apr  1 16:27:14 EST 2005

You can also use date formats to output the date in a specific way (so it can be used in scripts, or to form filenames):

$ date '+%Y%m%d-%H%M%S'
20050401-162855

But what happens if you want to see the GMT time, not the localtime? Just manipulate the TZ variable to fool date into believing we’re sitting on the GMT line:

$ TZ=GMT0 date
Fri Apr  1 21:30:21 GMT 2005

Another very frequent problem in scripts (specially log rotation scripts) is how to get yesterday’s date. Again, we can solve the problem by cleverly manipulating the TZ variable:

$ TZ=GMT24 date '+%Y%m%d'
20050331

Keywords: date, time, linux, yesterday, GMT, timezone, TZ

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What good is a system clock if you can’t keep it synchronized to the rest of the world? Well, hopefully, this is an easy task using the NTP daemon.

You’ll first need to install the NTP or XNTP packages, depending on your Linux/Unix version. Then, just create a file named /etc/ntp.conf with the following contents:

driftfile /var/lib/ntp/ntp.drift
statsdir /var/log/ntpstats/

authenticate no

server time.nist.gov
server ntp-1.cso.uiuc.edu
server sundial.columbia.edu
server timex.cs.columbia.edu

This assumes you are connected to the internet.

Restart your NTP package and monitor the synchronization progress with the ntpq -p command:

$ ntpq -p

remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*time.nist.gov   .ACTS.           1 u  485  512  377   69.062  -43.727   1.954
+ntp-1.gw.uiuc.e truechimer.cso.  2 u  513  512  377   63.117  -49.113   1.767
+hickory.cc.colu navobs1.wustl.e  2 u   40  512  377   44.482  -47.185   2.675
-cs.columbia.edu clepsydra.dec.c  2 u   33  512  377   44.732  -51.191   3.245

Pay special attention to the “tally code”, the caracter to the left of the hostnames. You’ll want to see “*” and “+” there. No signs or minus signs only mean your system is not properly synchronized. Also, your system may not be too far from the “reference” clock. If that’s the case, ntpd will panic and exit. To prevent this, set your clock manually to something close to the reference time or use “ntpdate” to do it for you automatically.

Keywords: time sync, ntp, ntpd, linux, unix, example

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