Re: JPEG fading and Sensor size
- From: "dh" <dragonkoi@xxxxxxxx>
- Date: Mon, 13 Mar 2006 07:53:57 GMT
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"cjcampbell" <christophercampbell@xxxxxxxxxxx> wrote in message
news:1142231597.476607.93870@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
| Most people are surprised to discover that JPG photos have such a short
| shelf life. You can slow the process down somewhat by re-copying them
| every three months, but eventually they will fade to almost nothing
| anyway.
|
| This deterioration is caused by UV rays and magnetic fields emanating
| from your computer monitor and other peripherals -- even your disk
| drive -- and cosmic rays coming from the sun.
|
| Think of the constant bombardment of your storage media as a kind of
| rain. Obviously, larger media such as DVDs and 5.25 inch floppy disks
| will be struck by cosmic rays, UV, and other particles much more
| frequently than smaller forms of media. Each particle can irrecoverably
| destroy some of your data. Back in the old days when disk drives were
| 12 inch platters (or even larger), data often did not last more than a
| few weeks! You should therefore store your most important photos on
| storage devices that are as small as possible, and use only one device
| at a time, since putting your data on two different drives more than
| doubles the risk that your data will be damaged.
|
| Compressing the JPEG file as much as possible will also reduce the
| damage done by cosmic rays and UV light.
|
| Another problem with large storage devices also applies to camera
| sensors. A larger storage device or camera sensor must have the data
| "stretched" over a larger area, creating holes in your pictures. This
| is why photos taken with the Canon 5D appear thin and faded compared to
| pictures taken with a cell phone. The cell phone has a smaller sensor
| and is able to concentrate the picture better. The most advanced
| cameras all have smaller sensors for this reason, while primitive DSLRS
| must continue to have large sensors in order remain backwards
| compatible with lenses and other accessories. Some camera manufacturers
| have attempted to load the larger sensors up with more pixels in an
| attempt to fill the quantum holes created by stretching the picture too
|
| thinly, but it is obvious that the quantum limits on number of pixels
| that can be placed on a large sensor has been surpassed. This is also
| why manufacturers of DSLRS tend to use inexpensive CF memory instead of
| smaller SD cards. After all, even though the CF card is larger, it does
|
| not appreciably thin out the picture more than it already comes from
| the sensor. The Nikon D50 does use SD cards, which accounts for why its
| pictures are brighter and sharper than those taken with the nearly
| identical D70.
|
| Placing an already too thin picture from a Canon 5D on a giant CD-ROM
| will almost guarantee very rapid fading and loss of sharpness. It is
| the worst of both worlds.
|
| JPEG quality is also affected by picture size. Obviously, a photo that
| has fewer pixels will concentrate the data more and store it in a
| smaller area, leaving it less vulnerable to deterioration.
|
| So, if you want JPEG pictures that last a long time, follow these
| simple rules:
|
| 1) Use a pocket camera with a tiny sensor.
| 2) Use the highest compression possible.
| 3) Use the smallest picture size available for your camera.
| 4) Store it on the smallest memory card available.
| 5) Make sure there is only one copy.
|
Thank you.
-Dave
.
- References:
- JPEG fading and Sensor size
- From: cjcampbell
- JPEG fading and Sensor size
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