Airport Security And Digital Files
* Card Safety
* Why Not JPEG For Everything?
* Will My Pixels Be Alive In 2525?
* Increasing File Sizes
Q) I purchased a digital camera and 1 GB card. I took my camera with me on a trip that required travel via airplane; I then noticed that my card wasn’t operating properly. The problem continued, so I contacted the manufacturer who was very supportive; they exchanged the card. When the new card arrived, it came in a sealed static shield bag that read: “Do not ship or store near strong electrostatic, electromagnetic, magnetic or radioactive fields.” Can the X-ray devices used in airport security affect the cards like they can affect film?
Jeffrey S. Fecher
A) It’s difficult to determine what caused your card to fail, but it probably wasn’t from the security devices at the airport. In recent testing by the International Imaging Industry Association, the U.S. Transportation Security Administration and SanDisk, there was no evidence of X-ray scanner damage to digital camera media cards.
The tests involved media cards and devices from a range of manufacturers that were loaded with a series of images. The cards were subjected to multiple passes through scanners currently used at airports throughout the U.S. After scanning, the image files showed no signs of damage.
In addition, separate tests were conducted using the walk-through metal detectors. Like the X-ray test, no damage to media or images was observed (that goes for handheld metal detectors as well). More information on the testing can be found at www.i3a.org/itip.html.
Why Not JPEG For Everything?
Q) The February 2005 issue featured an article on using the JPEG file format, “The Power Of JPEG.” My confusion is that after reading all the good info regarding JPEGs, it’s recommended that after opening a JPEG file, never resave it as a JPEG, but convert the image to TIFF. If JPEG is so good, why convert? I have hundreds of photos in JPEG folders and have never had a problem. TIFFs take up a lot of space; I’d need a new hard drive just to save converted JPEGs.
Frank P. Kennedy
North Branch, Minnesota
A) The short answer is that while JPEG is a great file format, it’s a compressed format. When you view (or open) a JPEG in an image editor, you’re converting a compressed file to an uncompressed display file. If, after making adjustments, you resave the file into a JPEG file format, you’re recompressing the file. Every time you compress, you’re throwing away data and adding artifacts-this can affect the quality of your image, especially in fine details and color gradations. Therefore, after making adjustments save your file as an uncompressed TIFF file.
If you’re only viewing the photo, you can keep the files in the JPEG format—just be sure you don’t resave the image. Closing it doesn’t change the file and isn’t saving it. Since the image already is on your hard drive, it’s saved—resaving means saving changes or telling the program to save it rather than just close it. This is an important distinction, closing vs. saving.
Here’s my workflow: After shooting, I download my files from the memory cards to my computer. After deleting any images that I don’t want and batch-renaming them to something more meaningful than DSC10001.jpg, I immediately archive them in their native format (some are JPEG, some are RAW) to an optical disc (CD or DVD, depending on the number of images). Then I begin any adjustments to the files that are on my computer, resaving the edited images in the native format of the image-editing application that I’m using. When I’m satisfied with my adjustments, I also save a copy of the file in TIFF format.
In The Year 2525, Will My Pixels Be Alive?
Q) If I record a bunch of pictures, say, on a DVD-R, as a way of archiving a large number of pictures, will I be able to retrieve and view the pictures 20 to 30 years from now?
La Crescenta, California
A) I can’t promise you’ll be able to view these files in 2035, but I can suggest ways to limit any future problems. There are three reasons that you might not be able to retrieve images decades from now:
1. The media on which the images have been stored has failed.
2. Hardware that can read your media no longer exists.
3. The file format of the images on the disc is no longer supported in existing operating systems or image-editing software.
Let’s tackle each problem individually.
1. As I’ve mentioned before, use good-quality media. Also, stay away from rewriteable disc formats. While rewriteables are okay for temporary storage, they’re not for archiving. Be sure to handle and store your media according to the manufacturer’s directions. Handling the disc by the edge, paying attention to proper labeling and storing discs vertically in a protective case can go a long way to safeguarding your data.
2. As far as hardware no longer being available, this is something about which you’ll need to be vigilant. So far, manufacturers have been diligent about supporting older optical media, such as CDs, with newer disc systems, like DVD. When new technology comes out, pay attention to how it supports your current technology. It may be the case that in 15 years, you’ll have to convert your discs to another format; however, because so much material is on the current type of media (CD and DVD), I don’t think a changeover will happen quietly, if at all. In other words, you’ll get plenty of notice.
3. Store your images in a file format that’s fairly well known. Using something like TIFF or JPEG will help future-proof your images. I’ve received letters from people who can’t open images that are only four years old because they stored the files in a proprietary image format no longer supported by any manufacturer.
There are some who would argue that you could use a file format that’s supported by a large company across several markets (consumer, semi-pro and professional), like Photoshop’s PSD file format. If we’re talking 30 years, you still might want to consider saving a TIFF right next to the PSD, just in case.
Increasing File Sizes
Q) I optimized an 11.1 MB photo to e-mail in Photoshop and the resulting size was 256 KB; Photoshop showed both files to have 11.1 MB total pixels. Why didn’t the total pixels reduce?
A) Photoshop is showing the uncompressed or pixel-for-pixel representation of the image, regardless of whether the file has been compressed. Here’s a simplified example. Let’s say you have an original image that’s comprised of all white pixels. A compressed file format could define the color of the first pixel as R=255, G=255 and B=255 (for the red, green and blue values of the pixel, with 0 being no intensity and 255 being maximum intensity).
Take that file into your image editor and use the software to compress the file so you can e-mail it. The software could look at your image and say, “Hey! The pixel in the upper-left corner of the image repeats for the rest of the image. Let’s just store the RGB values for the first pixel and put a note that says to repeat this pixel for the rest of the image.”
You can see that this instruction would save a lot of space; it would allow for a very small file to hold all the needed information to re-create the full-size image. (This is an oversimplification of the compression algorithms in image-editing software, but hopefully you’ll get the idea.)
If you were to take the “compressed” file and open it up in your image editor, the software will look at the instruction “repeat for 1 million pixels” and do what it says. In other words, it reconstitutes the image back to its original size. That’s what’s going on with your files.
If you have any questions, please send them to HelpLine, PCPhoto Magazine, 12121 Wilshire Blvd., Ste. 1200, Los Angeles, CA 90025 or firstname.lastname@example.org.