Re: Question re jpeg compression

On Sun, 25 May 2008 19:37:31 +1200, Peter in New Zealand wrote:

David J Taylor wrote:
Peter in New Zealand wrote:
[]
If anyone has any thoughts as to why converting and storing in png
format might not be such a bright idea (apart from the size issue) I
would appreciate your comments. I feel such a beginner with all this,
and the knowledge and experience of many others in this group is quite
self evident. My grateful thanks.

Peter,

Unless you have the uncompressed originals (i.e. not compressed JPEGs),
you will gain nothing by saving what you already have in PNG format.
The JPEG loss has already happened. Next time you scan or take a
photo, you can ensure it's lossless, and save /that/ in PNG if you
wish.

Actually, I find that a low-compression JPEG is actually good enough
for me. I don't have time to mess with processing "RAW" format images,
and I believe in getting the exposure correct in the camera at the time
of taking (if possible) rather than fixing it later in post-processing.
Perhaps that what comes from decades of taking slides!

Cheers,
David


Thank you David. I might be getting just a little narrow minded on this
one. Maybe I need to step back a little and get a more relaxed point of
view. If I understand what you are saying it means that, because my
little camera *only* saves in jpeg format, there's not too much point in
converting once they are on the computer. In fact I used jpeg quite
happily for about four years until I learnt about the issue of lossy
compression. Maybe it's a case of a little knowledge being a dangerous
thing (smile).

Being a type A personality I tend to be a fiddler, and I find it hard to
leave something alone when it's not yet perfect, but *good enough* for
its intended purpose. I'll just trundle on with jpeg for now, and keep
the issue in the back of my mind so I don't go mad on the hack and save
business. I absolutely agree with you that it's best to get it as right
as possible in the camera, and so minimise post shooting processing.
This is a bad habit I picked up years ago when I had my own darkroom. I
would take multiple shots of a subject, shortlist them from the negs,
and then settle on just one, which I would spend hours and hours on
until I had it just as I liked. Trouble is it tends to make one lazy
when shooting I think. Just blast off heaps on the understanding that at
least one will be in there somewhere that does what you want.

I should try to be more like Cartier Bresson who pioneered the concept
of the decisive moment in a scene. He became almost psychic in his
ability to anticipate it and hit the shutter release on his ancient and
(to us) primitive equipment.

Now I am rambling - please forgive me, and once again, thank you David
for your valuable comments.

No real reason to convert everything. Simply make it a rule and a habit
never to edit the original - work with a copy - then you can always go
back and start over.
.

Relevant Pages

  • Re: Question re jpeg compression
    ... David J Taylor wrote: ... Unless you have the uncompressed originals, you will gain nothing by saving what you already have in PNG format. ... I find that a low-compression JPEG is actually good enough for me. ... I don't have time to mess with processing "RAW" format images, and I believe in getting the exposure correct in the camera at the time of taking rather than fixing it later in post-processing. ...
    (rec.photo.digital)
  • Re: Question re jpeg compression
    ... you will gain nothing by saving what you already have in PNG format. ... The JPEG loss has already happened. ... and I believe in getting the exposure correct in the camera at the time ... Simply make it a rule and a habit never to edit the original - work with a copy - then you can always go back and start over. ...
    (rec.photo.digital)
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    ... I discovered that this format is prone to progressive quality loss over ... my camera only produces JPGs. ... tool and then once you make any changes saving as tiff would be fine, ... open them make a global change and resave as JPEG. ...
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