[Tiresias]

In September I posted a photograph on my blog of a monkey that had slipped out of its cage and was running around. The photograph was big, and the monkey small, so I photoshopped in a red arrow to save viewers the trouble of searching for it.

Today I was going through my archives and came across the photo. The red arrow has almost disintegrated. There are pixels bleeding everywhere. It's blotchy and mosaicked.

I didn't know that digital photographs decayed. What's up with that?

[starman]

JPEG quality level 1?

[peeb]

Every time you open and save a jpg, the quality deteriorates.

[starman]

Yeah, it's gotta be JPEG related. I have 20+ year old files that are fine.

[The Wolf]

ok, I'll bite...

PICS PLEASE!

[OldManMac]

Originally Posted by peeb 

Every time you open and save a jpg, the quality deteriorates.

Not true. If you open and change a file, even minutely, it deteriorates, as the algorithm changes the duplicate pixels it discards. Just opening and closing a jpeg does not change it.

[peeb]

Right - sorry - I meant changing it, since the op was talking about adding arrows.

[C.A.T.S. CEO]

Originally Posted by OldManMac 

Not true. If you open and change a file, even minutely, it deteriorates, as the algorithm changes the duplicate pixels it discards. Just opening and closing a jpeg does not change it.

I belive he said open and save, not open and close.

[turtle777]

Yeah, WTF did you not post a link to the pic ?

-t

[0157988944]

Ytf

[OldManMac]

Originally Posted by C.A.T.S. CEO 

I belive he said open and save, not open and close.

He did indeed. I stand humbled. (well, actually, I'm sitting)

[Railroader]

I have a few that have faded with time, yellowed and the corners chipped and folded. The worst is where the pic was folded and then a white line appeared.









C'mon, Is this a joke?

[turtle777]

Originally Posted by Railroader 

C'mon, Is this a joke?

Thank G*d

-t

[Tiresias]

Originally Posted by Railroader 

I have a few that have faded with time, yellowed and the corners chipped and folded. The worst is where the pic was folded and then a white line appeared.

C'mon, Is this a joke?

No, it's not a joke.

Here's the photo. The arrow was definitely not as crumbly when I uploaded the image.

[Visnaut]

Memory plays tricks on us.

When you photoshopped that image, the arrow naturally looked very crisp in Photoshop. And no matter how you saved the JPEG, either through "Save for Web" (which saves a copy) or just "Save As..." (which just saves the current image), the original document window will not reflect the effects of the compression. Rather, Photoshop keeps the original pixel data you edited, so that if you make further edits while the document is open and keep saving it, it doesn't have to recompress the image even further, and suffer generational loss with each additional save.

So when you saved it, you probably didn't pay much attention to the JPEG preview. What you remember is what you saw in the Photoshop document window.

To make matters worse, red visibly compresses more than other colours in JPEGs. The format is also not that great in handling sudden colour changes, unless you save at a very high quality. So the fact that the arrow is red on a dark background is another factor you should keep in mind.

Also, you mention you uploaded it to your blog. Are you sure your blog software doesn't resize images to a certain size, and therefore encode them as JPEG again? I find that server-side image utilities like ImageMagick or GD are not used to their full potential many times, and as such, produce shoddy images.

Digital files do not degrade, and if they did, you wouldn't be able to open them because the bitstream would be corrupt and thus the software wouldn't know what to do with it. It's just like the bullsh*t the sales people in AV stores spew about Monster cables having gold leads and maintaining a pure digital signal. Well no sh*t, it's just ones and zeroes going down a copper wire. If things were out of place, your tv or sound system would output static, not degraded content!

Anyway, that's all the insight I have.

[LegendaryPinkOx]

Ah hah ha! Look at the Monkey! I have no idea why, but primates are hilarious when in human environments.

[Tiresias]

Originally Posted by Visnaut 

Memory plays tricks on us.

When you photoshopped that image, the arrow naturally looked very crisp in Photoshop. And no matter how you saved the JPEG, either through "Save for Web" (which saves a copy) or just "Save As..." (which just saves the current image), the original document window will not reflect the effects of the compression. Rather, Photoshop keeps the original pixel data you edited, so that if you make further edits while the document is open and keep saving it, it doesn't have to recompress the image even further, and suffer generational loss with each additional save.

So when you saved it, you probably didn't pay much attention to the JPEG preview. What you remember is what you saw in the Photoshop document window.

To make matters worse, red visibly compresses more than other colours in JPEGs. The format is also not that great in handling sudden colour changes, unless you save at a very high quality. So the fact that the arrow is red on a dark background is another factor you should keep in mind.

Also, you mention you uploaded it to your blog. Are you sure your blog software doesn't resize images to a certain size, and therefore encode them as JPEG again? I find that server-side image utilities like ImageMagick or GD are not used to their full potential many times, and as such, produce shoddy images.

Digital files do not degrade, and if they did, you wouldn't be able to open them because the bitstream would be corrupt and thus the software wouldn't know what to do with it. It's just like the bullsh*t the sales people in AV stores spew about Monster cables having gold leads and maintaining a pure digital signal. Well no sh*t, it's just ones and zeroes going down a copper wire. If things were out of place, your tv or sound system would output static, not degraded content!

Anyway, that's all the insight I have.

I feel certain that the red arrow was crisp when I uploaded the image. But if you are right, and digital photo decay is impossible, then the explanation must be psychological.

How weird.

[turtle777]

Ok, so you got pwned by JPG compression. LULZ.

-t

[Railroader]

OP: "Digital photo decay" is not possible. You are not understanding JPG artifacts and image compression.

JPEG - Wikipedia, the free encyclopedia

[Railroader]

Dude, your picture is just falling apart!!! Your camera must be a piece of junk.

[James L]

Originally Posted by Railroader 

Dude, your picture is just falling apart!!! Your camera must be a piece of junk.

He didn't say he was using a Canon.

[ort888]

But what would happen if we put a digital photo on a conveyer belt?

[awaspaas]

Or the imagehost may recompress large images.

[Tiresias]

^ Blogger?

[Railroader]

Originally Posted by awaspaas 

Or the imagehost may recompress large images.

Or his ISP caches compressed images to "speed up" his web "experience".

[Teronzhul]

Originally Posted by ort888 

But what would happen if we put a digital photo on a conveyer belt?

Does the digital photo have wheels?

[RAILhead]

Originally Posted by ort888 

But what would happen if we put a digital photo on a conveyer belt?

That was an awesome MythBusters, wasn't it?

[RAILhead]

Originally Posted by Tiresias 

^ Blogger?

Blogger allows a pic to be up to 8MB -- and then I think it just won't let you upload. As far as I know, the only Blogger-sided compression is done when they make the preview -- but your full size is the same as the one you upload.

[AngelaBaby]

Originally Posted by James L 

He didn't say he was using a Canon.

Or a Kodak.

[Railroader]

Originally Posted by AngelaBaby 

Or a Kodak.

Or a Nikon.

We can play this game all day...

[Tiresias]

So what's good then? I've got a Sony. Works fine.

[Railroader]

Originally Posted by Tiresias 

So what's good then? I've got a Sony. Works fine.

Seriously? You don't get the sarcasm and joking that is going on here?

And if your Sony was working fine, why is your picture literally falling apart?!?! I mean sheesh, I can barely tell it is a picture of a lemur anymore.

[dav]

Originally Posted by Tiresias 

So what's good then? I've got a Sony. Works fine.

i think pentax has the DIDP* built in.

(* digital image decay protection.)