
Impressive JPEG Recompression - franze
http://www.jpegmini.com/main/shrink_photo
======
seats
I once worked somewhere where we had a need to store and transmit lots of
camera created jpegs in as efficient a manner as possible.

When working on this problem, I noticed that all digital cameras create jpeg
with 422 sampling. This might be a religious topic for some, but I cannot see
any visual difference between 4:2:2 and 4:2:0, even with high magnification or
on physical prints as large as 30 inch height. Simply sub-sampling to 4:2:0
along with subtle tweaks to quantization tables and with little effort we'd
bring a typical jpeg from 1-2MB down to 300-400KB.

We even did a series of experiments with people who look at photo prints all
day and they could not reliably pick the 'recompressed' images.

The only reason I think people really hold on to 422 or even 444 is that when
subsampling you can get nasty amplified errors if you are using two tools that
sampling with different algorithms or from different siting (i.e. imaging if
one tool picked odd lines and one picked even). Although the spec specifies
siting, I think there are still people who do it wrong, not to mention there
is still leeway for interpretation on how pixels are averaged for siting that
is not on a pixel boundary.

Bottom line is that if you know exactly what you are going to do with the
photo in the future you can compress a lot and quite easily with little risk.
If you have a lot of unknown processing in the future, things can get dicey.

~~~
andrewvc
For those wondering about the differences between 4:2:2 and 4:2:0, check out
<http://en.wikipedia.org/wiki/Chroma_subsampling#4:2:0>

------
brlewis
I started with this image: <http://c.ourdoings.net/td/kg/7cj8d5l.jpg>

It shrunk it 1.5x. I downloaded the _mini version and could see more artifacts
in the rendering of some of the smooth surfaces.

Then I re-uploaded the _mini version to jpegmini. _It shrunk it 1.3x._ This
shows that they are reducing quality, not just optimizing.

~~~
colanderman
Given that they claim to perform perceptual optimization, I would expect this.
Human perception wouldn't come into play if they were just optimizing the
image.

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yatsyk
I've successfully converted 99% quality image which became 4.4 times smaller
in size (identify shows 72% quality) after that I've converted same original
image to 72% quality with imagemagick and I've got similar compression.
Artifacts are look similar to jpegmini algorithm.

More interesting would be blind comparison experiment with with imagemagick
compressed images with similar compression ratio. I'd be surprised if they
could get 25-50% better compression with similar quality images.

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nraynaud
"So far, 14 patent applications have been submitted for various technologies
included in JPEGmini"

14 patents for one algorithm??? Somebody lost their mind, I worked on a camera
lens that had 10 elements and less patents than that. Craziness.

~~~
Udo
I suspect those patents are designed to serve as a deterrent for anyone to
enter the "JPEG optimization market".

Also, the service itself is underwhelming - it does next to nothing on JPEGs
that are already optimized.

~~~
brlewis
That will work. Even just the possibility of patents has served to keep people
out of that market:

<http://en.wikipedia.org/wiki/JPEG_2000#Legal_issues>

------
est
A comment from reddit:

<http://web_design.reddit.com/comments/jdo4v/_/c2balp2>

> barfolomew 13 points 20 days ago

> In my experience, one should stay away from Israeli tech startups. They're
> often very aggressive and fly-by-night operations. The culture clash between
> a north american firm is hard to deal with.

Is this really the case?

~~~
bradleyland
Fight generalization with generalization! When one encounters, "one should
stay away from <race or ethnic group>", always proceed with caution.

~~~
Dylan16807
While that is a reasonable policy, the statement in question is one of
_regional_ culture. Compare "silicon valley startups".

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ck2
Please add a non-flash alternative uploader.

I run as little flash as possible these days, security, tracking etc.

Aha! Look what I discovered:

<http://www.jpegmini.com/main/shrink_photo?no_flash=1>

There have been a dozen jpeg reduction attempts over the years, curious to
play with this one. Lossless jpeg cropping fascinates me more though.

~~~
palish
Is such sorcery possible?

~~~
ZeroGravitas
You can crop and rotate JPEGs losslessly:

<http://jpegclub.org/jpegtran/>

~~~
StavrosK
Doesn't cropping have to be within a certain size, though?

EDIT: Yep, looks like you can only crop it along the DCT block boundaries:

<http://www.ben.com/jpeg/>

------
DarkShikari
If you want recompression _without_ quality loss, try jpgcrush:
<http://akuvian.org/src/jpgcrush.tar.gz>

It does some quite evil things with progressive Huffman coding that most
people didn't even realize was possible.

~~~
anonova
I'd be interested in seeing how this works (source, docs, etc.), but
unfortunately I can neither get jpgcrush nor jpegrescan to output anything.

------
danbee
This introduces noticeable artifacting for me. jpegtran -- run via the
wonderful imgopt (<http://lyncd.com/2009/03/imgopt-lossless-optimize-png-
jpeg/>) script -- did a better job with the image I uploaded, with no quality
loss.

~~~
kilian
If you're looking for something similar but in GUI form, I made
<http://trimage.org> for that, installable in Ubuntu via _apt-get install
trimage_.

------
est
Another site from Sharon Carmel (the author based on WHOIS info)

<http://iloop.co.il/>

He/She is BeInSync founder and VP R&D

<http://iloop.co.il/main_page/2009/9/14/we-have-a-dream.html>

<http://www.israelinnovation20.com/tag/sharon-carmel/>

~~~
ZeroGravitas
Someone with that name posted to the WebP list about Jpegmini, they came
across as a bit of a kook (though it could have been a language issue I
suppose):

[https://groups.google.com/a/webmproject.org/group/webp-
discu...](https://groups.google.com/a/webmproject.org/group/webp-
discuss/browse_thread/thread/48f1ab16bd7af7e1)

------
vytis
Well the quality seems quite a bit worse for the picture I tried. Original:
<http://postimage.org/image/94ol50ck/>, compressed:
<http://postimage.org/image/14712qgjo/> The resulting image has way less
detail in higher frequencies.

~~~
est
Looks like the compressed version is a bit sharper to me.

~~~
eftpotrm
If the compressed version is apparently sharper than the original file, that's
an artifact surely? It might be pleasing in some contexts but it's not an
accurate representation of the original file in that aspect.

~~~
est
I mean, vytis claimed that

> The resulting image has way less detail in higher frequencies.

But the compressed version actually exposes more detail.

~~~
waitwhat
_But the compressed version actually exposes more detail._

No. It really doesn't.

It adds a couple of visual filters (brightening, sharpening) before
recompressing, but these don't "expose more detail", but rather all three
steps actually introduce additional errors. Errors that trick they eye into
seeing a "better" image, but errors nonetheless.

~~~
sharoncarmel10
JPEGmini does not apply any filters on the photo, no pre processing
whatsoever. JPEGmini went through BT.500 certification, the result was that
given 2 images 1. source 2. recompressed, the tester could not tell which is
the source and which is the recompressed. Enjoy.

~~~
CJefferson
I'm not sure what BT.500 certification is, but I can certainly tell the
difference on some (not all) images, when recomposed.

Are you attached to JPEGmini? If so, would you be willing to bet that I cannot
tell if a photo of my choice has gone through your system and been compressed?

------
leag
Custom quantization tables and chroma subsampling, with a bit of hype

------
biot
Wow, the Dropbox sample photo Costa Rican Frog was reduced 4.6x and actually
looks sharper than the original. The detail in the middle of the back appears
to have more contrast in the minified version. Other than some sharpness and
some minor artifacts in the eye, the before and after images look identical.
Except the original is 346KB and the JPEGmini version is 75KB.

~~~
CWuestefeld
_looks sharper than the original ... more contrast in the minified version_

That's not a good thing, to my way of thinking. When I'm processing my photos,
I'm choosing very carefully the amount of sharpness and especially contrast in
the image. I'd be very unhappy with a tool that alters these.

~~~
biot
It looks to be a per-image effect and not intentional. Most images I tried,
there was no apparent difference. Then again, most images had only about a 30%
savings. For an almost 80% savings, I'm not surprised if there's no free
lunch.

------
userulluipeste
It's impressive, indeed! I guess they use some feedback loop when
recompressing, because there doesn't appear to be no quality loss, even on the
smallest details. I've tried one file of 1.4MB of an Australian nature
landscape. Recompressed went under 400KB. I wonder if there isn't an offline
tool available. For free if possible :)

~~~
pyre

      > there doesn't appear to be no quality loss, even
      > on the smallest details
    

I do not think that means what you think it means.

~~~
azulum
inconceivable!

------
est
two relevant papers

<http://spie.org/x648.html?product_id=872231>

<http://spie.org/x648.html?product_id=872230>

from SPIE Electronic Imaging 2011 conference in San Francisco

------
artursapek
Wow it looks like they've caught on to something. I've tried a few ~1.2 MB
scans of film negatives and it shrunk the sizes 5x and 6x with no differences
that I can see. When I tried smaller files however the difference got down to
~1.5x with some more obvious noise removal so I think it's just exploiting
inefficiencies in how large jpg's are encoded.

I also love the sense of humor. _"SEEMS YOUR PHOTO LOST SOME WEIGHT!"_

------
cateye
I don't see the point. I upload a jpeg that is 51% progressive compressed in
Photoshop and Jpegmini can reduce the size 1.2x.

Isn't really worth the effort.

------
swatthatfly
This would be interesting if it was not web service. I would like to have an
executable with command line access, in order to run batch commands. I don't
want my images stored/processed on their server. Surely they can think of a
license price.

------
iaskwhy
A more web-ish example: a static jpg banner with 900x400 was 46KB and got
compressed into 35KB (reduction of 1.3x). Another similiar banner with 43KB
resulted in a compressed 29KB (1.5x smaller). This is very good!

------
rglover
Does what it says. Took a 1MB image and took it down to about 300kB. Only
complaint is that you have to sign in (using Facebook/Google) or create an
account to do batch uploads.

------
geuis
Every jpg image I try fails. This happening to anyone else?

~~~
Fast7
No. I tried Windows7 Chrysanthemum.jpg under Sample Pictures folder, it works,
impressively.

------
twidlit
Whoa! 1.15mb jpeg | 1.1mb imageoptim | 422 kb jpegmini

------
jmah
_So far, 14 patent applications have been submitted for various technologies
included in JPEGmini_

Must be a good chunk of change behind it.

~~~
ck2
I wonder if one could figure out the algorithm by making a specially crafted
image and recycling it through their service several times to see what it does
where.

------
TomGullen
This is great, shaved ~20% off my splash image, 100kb to 80kb with no
noticeable loss of quality.

Good job!

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silon
Ratio display needs to be fixed:

99k -> 71k is not usefully presented as 1.4x, but better as ~30%

~~~
sukuriant
Or 70% the size.

------
rorrr
Tried it. It just saves it with worse compression, resulting in more
artifacts. Not impressed.

All these posts "whoa I compressed my 1MB image to 400KB" are laughable. It's
not like it's lossless.

~~~
edrokov
You are very right, rorrr

