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Mar 27th, 2004, 11:27 AM
#1
Thread Starter
Fanatic Member
JPEG viewing loses info?
I just had an interesting conversation with a photographer. She said that JPEGs lose bits of information everytime you open/close them (wether or not you save). I was skeptical but she's been using them more than me...
Anyone have any information on this? (I would assume JPEGs only lose info if you modify them, due to compression)
Don't pay attention to this signature, it's contradictory.
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Mar 27th, 2004, 12:39 PM
#2
I havn't studied lossless compression that much...but it sounds werid....if you open up a file and then don't save it...it will be the exact same information you are reading the next time you open it up....so I guess she is wrong....
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Mar 27th, 2004, 02:07 PM
#3
Re: JPEG viewing loses info?
Originally posted by alkatran
I just had an interesting conversation with a photographer. She said that JPEGs lose bits of information everytime you open/close them (wether or not you save). I was skeptical but she's been using them more than me...
Anyone have any information on this? (I would assume JPEGs only lose info if you modify them, due to compression)
I'll bet she'll also tell you that the more data you add, the heavier a laptop gets. 
Btw, is she blonde?
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Mar 27th, 2004, 02:09 PM
#4
Thread Starter
Fanatic Member
Apparently she heard it at some meeting for something. So there's a group of people who believe this now..!!!
Don't pay attention to this signature, it's contradictory.
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Mar 27th, 2004, 03:49 PM
#5
Frenzied Member
A lot of web site banners are jpegs, and they get thousands of views per day, and not much loss of data there. sounds like a bunch of bull 
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Mar 27th, 2004, 04:03 PM
#6
Maybe that is why they have started to use flash here at this site..
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Mar 27th, 2004, 04:08 PM
#7
transcendental analytic
Originally posted by NoteMe
I havn't studied lossless compression that much...but it sounds werid....if you open up a file and then don't save it...it will be the exact same information you are reading the next time you open it up....so I guess she is wrong....
thats lossy compression note, not lossless 
Use  
writing software in C++ is like driving rivets into steel beam with a toothpick.
writing haskell makes your life easier:
reverse (p (6*9)) where p x|x==0=""|True=chr (48+z): p y where (y,z)=divMod x 13
To throw away OOP for low level languages is myopia, to keep OOP is hyperopia. To throw away OOP for a high level language is insight.
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Mar 27th, 2004, 04:16 PM
#8
Din lille snørrunge........
PS: I am glad I looked that one up...
After creating the JPEG standard described above, the committee started to look at some of the criticisms of the existing standard. High amongst these was the poor quality (and lack of integration) of lossless coding in the standard. With this in mind, the committee developed the JPEG-LS standard - ISO/IEC IS 14495-1 | ITU-T Recommendation T.87.
from the JPEG.org site...
http://www.jpeg.org/jpeg/index.html
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Mar 27th, 2004, 04:33 PM
#9
Re: JPEG viewing loses info?
Originally posted by alkatran
I just had an interesting conversation with a photographer. She said that JPEGs lose bits of information everytime you open/close them (wether or not you save). I was skeptical but she's been using them more than me...
Anyone have any information on this? (I would assume JPEGs only lose info if you modify them, due to compression)
What happens if the JPEG is on a CD
I've heard that opening a JPEG and saving it (even if no changes made) cuases the compression algorithm to be run on the file each time thereby compressing an aleardy compressed file and hence the loss of detail.
This is why you should edit and save your image in TIFF format or similar and then only save it as a jpeg when you are done. Keeping a copy of tthe old TIFF image of course.
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Mar 27th, 2004, 04:35 PM
#10
Thats true...that I can agree on...but if you have more then one layer TIFF won't do....use the file format of the image application you are using...that one will save it all, but not be very portable...
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Mar 27th, 2004, 05:27 PM
#11
transcendental analytic
Re: Re: JPEG viewing loses info?
Originally posted by visualAd
What happens if the JPEG is on a CD
I've heard that opening a JPEG and saving it (even if no changes made) cuases the compression algorithm to be run on the file each time thereby compressing an aleardy compressed file and hence the loss of detail.
This is why you should edit and save your image in TIFF format or similar and then only save it as a jpeg when you are done. Keeping a copy of tthe old TIFF image of course.
that depensd on the application. PSP for instance allows you to save the image to disk leaving the image intact in memory. Nevertheless if you want to do changes later on, its better to use a lossless format.
Use
writing software in C++ is like driving rivets into steel beam with a toothpick.
writing haskell makes your life easier:
reverse (p (6*9)) where p x|x==0=""|True=chr (48+z): p y where (y,z)=divMod x 13
To throw away OOP for low level languages is myopia, to keep OOP is hyperopia. To throw away OOP for a high level language is insight.
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Mar 27th, 2004, 05:31 PM
#12
transcendental analytic
whatever we were talking about lossy compression here, not lossless, even though jpeg has both
Use
writing software in C++ is like driving rivets into steel beam with a toothpick.
writing haskell makes your life easier:
reverse (p (6*9)) where p x|x==0=""|True=chr (48+z): p y where (y,z)=divMod x 13
To throw away OOP for low level languages is myopia, to keep OOP is hyperopia. To throw away OOP for a high level language is insight.
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Mar 27th, 2004, 06:01 PM
#13
:shuts up:
:and will now stop pretending he knows what these guys are talking about:
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Mar 27th, 2004, 07:05 PM
#14
Hehe...to both of you...
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