Fix missing thumbnails in Nautilus

A Tech article with View Comments posted 6 February 2008.
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As I begin assembling the picture package for my J-term trip to Israel and Palestine, I’ve run into a problem: with high-end digital cameras, the JPEG-compressed image files are larger than 5 MB, and Nautilus (the default Ubuntu file manager) won’t create thumbnails for pictures that size.

The solution: a bit of configuration in gconf-editor. Navigate to key /apps/nautilus/preferences and increase the size of thumbnail_limit to something more reasonable for modern cameras.

UVB bulbs and Veiled Chameleons

A Family article with View Comments posted 4 February 2008.
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Thanks to a concerned reader of my last post about veiled chameleon light bulbs, we realized that a UVA-only was not sufficient to take care of Ezekiel. Jenni (the reader, not my wife Jennifer) was concerned that we had bought a basking bulb instead of a proper UV bulb, and she’s quite right: there is some evidence that without proper UVB irradiation, veiled chameleons may develop metabolic bone disease and die. There is at least one study that suggests that veileds don’t really need UVB if they are properly supplemented with vitamin powder on their food; nevertheless, we subscribe to the philosophy of “better safe than sorry.”

Thus, we replaced our ordinary UVA bulb with a UVA/B bulb to help encourage healthy vitamin D3 production. The bulbs are more expensive, but it’s definitely worthwhile. And good bulbs like the Reptisun line of bulbs are now available in compact fluorescent, so you can use your old reflector.

Two items to remember: UV bulbs are no substitute for a infrared bulb of some sort to allow for sunning and temperature self-regulation. Also, UVB bulbs will continue emitting visible light for a long time, but they run out of steam in the UV spectrum within 12 months, so replace your bulb(s) yearly.

Two simple ways to recover photos from a broken SD card

A Tech article with View Comments posted 1 February 2008.
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I just got back from a 18 day trip to Israel and Palestine, and my classmate Dave’s SD card for his digital camera gave out right at the end of the trip. He gave me the card to try to recover the pictures, and I was pretty successful. Here’s what I did.

I needed to grab a pristine copy of the SD card’s data without hardware errors getting in the way. So I used dd to take a snapshot of the card:

sudo dd if=/dev/mmcblk0 of=sdcard.img bs=512b skip=1 conv=noerror

The /dev/mmcblk0 should be replaced with the location of your SD card reader. The magic sauce is conv=noerror, which prevented me from getting an error with Dave’s card about 40% into a 1G card.

First I tried recoverjpeg, available from your friendly local ubuntu repository. Run this program like so:

recoverjpeg -v sdcard.img

Simple and straightforward. This program recovered 108 pictures, all with EXIF data intact (except for no date/timestamps – oh well).

I also tried photorec, which is part of the testdisk package in Ubuntu. Photorec is more complicated, but it recovers more kinds of data too. Fortunately, it’s menu driven and pretty self explanatory. Invoke that program with:

photorec sdcard.img

Not only did this program recover most of the pictures (106), but it also grabbed all sorts of interesting metadata in the form of txt and xml files. It also did a good job with the EXIF data, except for the date/timestamps.

Altogether, I got slightly better results with recoverjpeg, and it was easier to use. Your Mileage May Vary. I was surprised at how easy it was to recover these images!

Special thanks to Cédric Blancher, whose article “Digital Photos Recovery” was very useful as I prepared this article.