Would it do a similar thing if you just kept re-encoding at the same compression? (I guess by converting to a bitmap in between jpg encodings. Maybe I should try...)

hadto, great idea—I think I'm going to have to make a version of something like this, too (obviously with a big credit to your awesomeness).

Question, though: are you increasing the compression during this, or are you just setting it at the same quality level (say, 50 or 60) and running it over and over?

Just curious! Thanks for this awesome study!

this is cool. i'm a painter who's been working with something very similar to this for the last year or so. check it out: williamherwig.com/2008.html

nice job, but why stop at 600? it was just getting interesting!

Wow, most impressive. Well dne!

RT
online-privacy.pro.tc

Similarly, what happens when you save a PNG image 600 times: vimeo.com/3822911

wow, I'm switching to RAW after seeing this!

i like it too

a digital jj murphy print generation

it would be more interesting to see what happens when you keep the same level of compression throughout the process: the repeated lossy compression will still cause quality degradation, even with a high quality setting.

Sorry to say it is really unuseful.

When using "slightly more compressio" with
compression = map(i, 0, 600, 1, 0)
you are deliberately smashing the picture.

Let me show you:

As iterations go on, "i" grows until 600, and the returned value from map call decreases towards "0".

So, as iterations go on, you are using a worse quality recompressing for an already an already degraded image. On the last step you save as quality 0 from an image wich has already been smashed out by previous low quality compresions.

You are deliberately lossing quality on every step, but you are even loosing more quality on each step than in previous one. What did you spect to get from that process ?

php:

$file = 'chicago_hdr_west02_1280.jpg';
$im = imagecreatefromjpeg($file);
$i = 0;
for ($q=100; $q>0; $q--) imagejpeg($im, "out_".(++$i).".jpg", $q);


then to make a movie:
ffmpeg -r 10 -b 180000 -i out_%d.jpg test.mp4

Reminds me of this: rhizome.org/object.php?47761

Sorry to say then itis a crazy idea. Of course you are going to break the image if compresing at ZERO quality !

I think most of people wide the internet mis-understood your point as being demostrating jpeg degradation effect when saving once and again, like
Brad Miller did:
"wow, I'm switching to RAW after seeing this!"
Brad, you'd better use RAW, but not because of this test.

Also, hadto, as far as you apply more compresión over already compressed images, you are exponentially degrading the image. Brian More was right.

What you have here is the "photocopy of a photocopy of a photocopy..." effect compounded by using a different (cheaper) copying machine each time.

The quality level parameter would indeed be linear if you applied it to the *original* image at each iteration, i.e. q_i = (1 - i/600). By applying it to the *previous* image, you have something else.

Regardless, what people are really interested is in seeing the effect of saving a jpg repeatedly at a *fixed* quality level (say 0.8).

Care to put together a small video on *that?*

Thanks for doing this! Nothing happened to image, huh? Are you sure you are performing the recompression each time? The effect should be greatly diminished, but you should start to see some tiny effects as the iterations increase. Perhaps 600 were not enough...

See the comments at reddit.com/r/technology/comments/86v2z/see_what_happen_when_saving_600_times_a_jpg_image
From what I understand, the JPEG algorithm cuts some frequencies in the image, so once they are cut there is nothing else to do. In practice, it does stabilize after a few steps (there are some rounding effets possibly), check with the md5 scripts on that page.

After a little digging around, it has become clear that the steps in the JPEG algorithm reach a fixed point after the second and subsequent iterations. Most implementations are configured to recognize this situation and basically leave the image untouched.

So, the new video is correct. "Nothing happens," indeed.

Boring, isn't it? ;-)

Here's a short film I made in 2005 using the photocopy-of-a-photocopy idea. 4,600 copies, 12 copiers - lumeneclipse.com/gallery/26/stewart/

It's incredibly scary. Let's make .tifs !

HI i love this stuff!!!!

Here´s a video made with a code error provocated
vimeo.com/5014465

greetings!