jpeg format losing info

[swedeheart]

Question about .jpg and .png image formats. I am familiar with the basic differences between them. My question concerns a statement I've only come across once and I'm wondering whether it is correct or not. It said jpeg images lose information not only every time you save them down anew but also every time the internet page they're located on IS VIEWED. Really??

[scotman]

Hi Kit

Long time no hear from you.
I am not an expert on image storage formats but I can think of no reason why the image should degrade with repeated viewing. I would not worry about this.

[swedeheart]

Hi John, good to see you still oot an' aboot:) I haven't forgotten my old AnswerBank buddies, I'm just not fluent enough to be on ChatterBank. ~ I can't think of any reason either but that's why I'm asking. Why do men on AB always tell me not to worry, lol...! ...when I'm just interested to learn:) /Kit

[mjwman]

A .jpg is a compressed file. It looses info each time it is SAVED.
It says "oh sky, lots of blue, can do without some of that" sort of thing.
You choose the level of compression.
I think viewing on internet is therefore immune from degrading the original image.

[scotman]

Sorry if I sounded patronising - not intended. I believe the info you have been given about degrading image quality is just wrong.

[swedeheart]

Yes that is what one would assume isn't it mjwman. I should have saved the link to where I read it - I think you would all have agreed it had a trustworthy ring to it. But it makes no sense...

Aww scotman I know you're not patronising xx

[Buenchico]

Accessing a file on a computer or server doesn't change the data within that file. (If it did, you'd find the text in Microsoft Word documents changing whenever you accessed them on your PC!).

As others have said, it's only saving a JPEG file that results in data loss.

A relevant link:
http://www.pcuser.com...156A5CA256EA300834001

Chris

[swedeheart]

Thanks Chris. Yes it would have been weird had it been true...!

[Hard@it]

Just thought it was only me, but I have lost lots of jpg photos within my Imago storage. not to be found again

[swedeheart]

Lol H@i, are you taking the proverbial...? :) I didn't lose any photos - read again:) If indeed you've lost yours, do post a question about it here on AB - seems to me there are often ways of recovering at least some of the data even when you think all is lost.

[VHG]

I always save my master pictures as downloaded from the camera on a CD or DVD or external hard drive before making any changes to copies of them.

I believe even rotating a jpeg image loses some information.

[swedeheart]

I'm confused now as I'm no longer sure who's talking to whom about what, ha ha... Sounds like a good call at any rate, VHG. (But that wasn't what my question was about, you see, hence my confusion here. Thanks anyway. Perhaps you were answering H@i :)

[beso]

Data can be lost from a jpg when saved. However decent programs that handle jpg format allow the compression level to be controlled. If the quality is set at 100 percent when saved it won't drop any further detail.

If the program does not allow the quality/compression to be controlled then saving in that program should be avoided.

[swedeheart]

Hi beso. That wasn't what I was asking about but thanks anyway:) I've had my answer way up north in this thread so no more replies really necessary unless somebody begs to differ with the unanimous opinion stating that a jpeg image located ON A WEB SITE* will not lose info however many times the page that it's located on is viewed. (It would have been very odd had it been so. But that was, at any rate, what I was asking.) Thanks all!

*Spare, can we have italics soon do you think? ^^I sound rude:(