
|

Card Safety
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
Yardley, Pennsylvania
|
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 Adminis- tration 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?
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
|
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?
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?
|
George Wharton
La Crescenta, California
|
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
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?
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
[email protected].Visit
our Website at www.pcphotomag.com
for past HelpLine columns.
|

|