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Will jpg lose quality if open and not saved ?

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Edymagno

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Hi all !

I have 2 fellow photographers that believe that a jpg file from the hard-drive lose quality every time you open it in PS, even if you do nothing and close it.

1.- I believe that if I open the file and close it, actually the file was never touched, (it didn´t lose quality)

2.- I believe that if I open a jpg file and perform one or several modifications but close without saving changes, the file in my hard drive was never touched (it didn´t lose quality)

3.- I believe that if I perform 1000 times the action described in No. 2, the jpg will remain unaltered.

Who is right ?

Am I right or wrong in my 3 statements ?

Thanks everybody

Eduardo

PS: This post will be cross-posted in Mac Talk
 
Its just like a Word document. If you open it and then shut down Word without changing a document then the file is exactly as it was before you opened it. Even if you make changes, but dont save it nothing changes on the drive. Photos are the same no matter the format. If you dont save it how can whats stored on the drive change. The only time jpgs loose quality is when you save them.

Jason
Edymagno said:
Hi all !
I have 2 fellow photographers that believe that a jpg file from the
hard-drive lose quality every time you open it in PS, even if you
do nothing and close it.

1.- I believe that if I open the file and close it, actually the
file was never touched, (it didn´t lose quality)

2.- I believe that if I open a jpg file and perform one or several
modifications but close without saving changes, the file in my
hard drive was never touched (it didn´t lose quality)

3.- I believe that if I perform 1000 times the action described in
No. 2, the jpg will remain unaltered.

Who is right ?

Am I right or wrong in my 3 statements ?

Thanks everybody

Eduardo

PS: This post will be cross-posted in Mac Talk
Click to expand...
 
Thanks Jason for your response.

See, this friend argues that even when not saving any change, Photoshop will perform a new compression.
He says the catch is in the compression.

I am not computer literate really, but just common sense dictates me that if everytime I close a jpg without saving, it just disappears intantanoulsy from the PS interface, and on the contary, if I save it, it takes a while for PS to close the file. This indicates me the unsaved file remains untouched.
Best
Eduardo
Jason Edwards said:
Its just like a Word document. If you open it and then shut down
Word without changing a document then the file is exactly as it was
before you opened it. Even if you make changes, but dont save it
nothing changes on the drive. Photos are the same no matter the
format. If you dont save it how can whats stored on the drive
change. The only time jpgs loose quality is when you save them.

Jason
Click to expand...
 
When you open a picture, it's copied into RAM and opened in whatever program you're using (which has also been copied into RAM to run). If you close a picture without saving, the RAM copy just goes "poof." The file on your hard drive doesn't change unless you save again using the same file name.
 
nt
Ed
 
I advise that you take no computer advice from this "friend."
--

'] http://img20.imageshack.us/my.php?image=p10000032wo.jpg]
p10000032wo.th.jpg
[/URL] [/URL]
 
Unfortunately this is an urban myth that seems to be getting more widely spread. Even Bryan Peterson, in his book 'Understanding Digital Photography' says that a jpeg will degrade each time it's open/closed.

--
Frank Hollis
Mass Spectroscopist in the UK
Can0n 2oD
 
hollis_f said:
Unfortunately this is an urban myth that seems to be getting more
widely spread. Even Bryan Peterson, in his book 'Understanding
Digital Photography' says that a jpeg will degrade each time it's
open/closed.

--
Frank Hollis
Mass Spectroscopist in the UK
Can0n 2oD
Click to expand...
I just had a similar argument with a friend who thinks it happens with video files too. Of course, he had heard it from a friend who had heard it from a friend...

The level of ignorance in the world never ceases to amaze me. :-)

----------------
http://www.pbase.com/tmalcom/
 
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