Deb wrote:
> I am relatively new to Legacy and computers in general. I have recently
been scanning a box of old
> documents and pictures onto a CD. Now I am trying to learn how to put
them into my Legacy
> program. The pictures are easy. But I noticed on Geoff's beginner video
that he has old family Bible
> sheets, land doc. signatures, etc. as jpg. I scanned all my documents in
PDF and all my pix in jpg. Will
> I have to go back to RI (over 1000 miles away) and rescan them to jpg if I
want to put them in
> Legacy? Or does anyone know how I convert them? I thought I had heard
that JPG files deteriorate
> in quality over time and usage, which is why I used PDF. I have Legacy 5
Standard Ed.
JPEG files don't "deteriorate in quality" over time and usage.
The commonly used JPEG formats are what are considered to be lossy,
but there are other JPEG formats defined by the JPEG committee which
are not lossy or very nearly not lossy. Also even the commonly used
formats can use a range of algorithims which trade off compression for
data loss. That is, parameters can be set to compress more and lose
more data or to compress less and lose less data.
So what do I mean by the term lossy? Lossy is a term used to mean that
the JPEG encoding algorithms can and usually do cause some loss of detail
in a picture. This loss of detail is usually very minor. Many digital
cameras
can only save files as JPEG files. Yet many of these images are quite fine.
You would have to look very carefully at greatly enlarged areas of the
picture
to see the loss of detail. The losses only get worse if you open the
image, modify it and save it as a jpeg file again. If you repeatedly read
the same file and don't modify it, it will not lose quality. How can it if
the original file remains unchanged?
One of the advantages of digital file storage is that the bits which make
up the file are protected by various encoding schemes from degradation,
so that when a file is read in, the lost bits can often be restored. There
are many ways to do this and books have been written about how this
works. It works very well. That's why banks and other financial
institutions
trust their accounting records to computers. So files don't degrade over
time, if they are properly maintained. The media can fail, but there are
electronic techniques to recover the data and rewrite it on new media.
One way to avoid JPEG's loss of detail is to save files in a Lossless
format,
such as .tif which Geoff mentions. Others are PNG and bitmap formats.
There are also lossless formats used by Paint Shop Pro and Photoshop,
but these are "proprietary" to those programs. I do think Geoff overstates
the case when he writes that "later if you want to modify it [.jpg file] or
use it for a high-quality publication, you cannot". You certainly can
modify
a .jpg file and save it several times. I know, I've done it. And I've
compared the quality of the file after 10 generations of doing this.
I did see small losses in quality, but not much. Perhaps it would not
be suitable for high-quality publication, but perhaps it would be, just
not perhaps as an 8x10 image.
Also, JPEG files don't lose data over time, just sitting on a disk or tape
somewhere, unless of course you write data to tape say and leave
the tape alone for say 100 years so that all the iron oxide (rust)
demagnitizes and you are just left with a pile of rust and tape backing.
If ya wanna know more details, write me off list and we can discuss.
jr
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