Google Increases JPEG Compression by 35% Without Loss in Image Quality

cageymaru

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Google has developed a new compression algorithm for JPEG images that shrinks them 35% smaller than today's methods without image loss. According to the Google blog announcement post, "Guetzli is a JPEG encoder for digital images and web graphics that can enable faster online experiences by producing smaller JPEG files while still maintaining compatibility with existing browsers, image processing applications and the JPEG standard." Guetzli focuses on compression at the quantization stage as that is where more visual degeneration of the image occurs.

To accomplish this, Guetzli is using psychovisual research based on HVS or the human visual system model. HVS is the study of what humans perceive to be suitably, visually similar. This research worked for the advent of color television as a way to save on bandwidth, and now jpeg compression. This modelling takes longer to process than conventional methods, but in studies 75% of people preferred the Guetzli method over libjpeg even when libjpeg was allowed to use a larger file size. Pretty impressive!

It is our hope that webmasters and graphic designers will find Guetzli useful and apply it to their photographic content, making users’ experience smoother on image-heavy websites in addition to reducing load times and bandwidth costs for mobile users. Last, we hope that the new explicitly psychovisual approach in Guetzli will inspire further image and video compression research.
 

Nenu

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Yeah but how does it cope with a zoomed image?
Higher compression of this nature will result in more artefacts that might be ok 1:1, but larger?
 

Ultima99

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Interesting, but change is hard. I wonder what the realistic uptake potential on this is and over what time frame?
 

Gigus Fire

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There's another method to make pages load faster, block all the spam.
Block all ads is even better. Especially on mobile devices.
I've found that chrome is really popular on phones, but doesn't allow for plugins. Firefox allows for chrome plugins. No need to root and apply ad blocking software, just do it through firefox.
 

Jagger100

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Does this mean I can 'zoom and enhance'?

Anyway, its not clear if this is a 35% reduction without additional loss or is this a 35% reduction that is lossless or is this a 35% reduction that is perceptually lossless.
 

Spidey329

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Does this mean I can 'zoom and enhance'?

Anyway, its not clear if this is a 35% reduction without additional loss or is this a 35% reduction that is lossless or is this a 35% reduction that is perceptually lossless.

Pretty sure the quote explains this is based on perceptual loss as it discusses the testing methodology of comparing it to larger file sizes to see if the test subject perceived a degradation in image quality.

So the loss is there for there to be 35% efficiency gain, but the users it was tested against did not perceive it.
 

DocSavage

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So, in theory, they could split the difference and make images 20% smaller while increasing perceived quality.
 

prime2515102

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It's the 21st century and we still have bandwidth issues. The web should be filled with uncompressed images by now. :p
 

MrBonk

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Just what we need, more compression artifacts! (Joking)

If it can get visually similar to max quality JPEG currently though, it might not be so bad. (Which is nearly visually indistinct from lossless in a lot of ways. You'd be hard pressed to pick out the difference. It's not blatantly covered with artifacts as every level below max quality is)

Source Image: http://u.cubeupload.com/MrBonk/SG.png
Here's an image showing the difference between a lossless image and max quality JPEG (+3EV to make it more visible)
maxqualitydifference.png

And the same with two levels lower of compression
twolevelslowerJPGdif.png



In this day in age though, unless you are making a set of separate images strictly for mobile browsing. There is no excuse not to use Max quality JPGs.
Which just reminds me the 3DS eShop was rather horrible about this. Super compressed images for everything.


EDIT: I ran the same image through their new encoder and here is the difference file at 100% JPG.

newgoogleencodermaxq.png


Very impressive!

File size difference however is not as impressive. Either some kind of bug or perhaps the encoding is just that much higher quality at max quality.

PS-Max quality JPG -844kb (3-Scan)
PS-Level 10 quality JPG-393kb (3-scan)
Guetzli-quality 100 JPG- 1.25MB

Edit2: Actually I am not so sure.
Here's the same image run through Infranview's JPG encoder ((LibJpeg-Turbo))at 100 quality , similar file size as Guetzli 1.28mb
infranviewmax3ev.png
 
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sleepeeg3

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They only needed to do this about 20+ years ago... Probably more useful for digital camera photos.

Different programs have different .jpeg compression algorithms anyway. Photoshop always seems to store comparably worse picture quality for a larger photo size. Meanwhile, I have an old copy of PaintShopPro that results in substantially reduced .jpeg file sizes, for slightly improved .jpeg picture quality, when saving with maximum settings in both programs. FastStone Photo Resizer also results in reduced file sizes over PS.
 

Jagger100

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It's the 21st century and we still have bandwidth issues. The web should be filled with uncompressed images by now. :p
Tell that to people on data plans. Who don't really need a hi-res image along with the financial considerations.

The JPG is a way to keep images small but have the detail there for people who are using big boy computers instead of pocket computers.
 

Valset

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Still JPEG, still compatible with everything else out there.

Sure, why not. Hard to find anything bad here.
That depends on how fast it is. You could see it be an issue if it requires more horsepower
 

SvenBent

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Guetzli is no quite news. but nice seeing it gets mainstream attention now,

Guetzli uses a more more CPU power to improve the psychovisuel part of encoding the picture lossy. aka it actually tries to make things look "better"



They only needed to do this about 20+ years ago... Probably more useful for digital camera photos.

Different programs have different .jpeg compression algorithms anyway. Photoshop always seems to store comparably worse picture quality for a larger photo size. Meanwhile, I have an old copy of PaintShopPro that results in substantially reduced .jpeg file sizes, for slightly improved .jpeg picture quality, when saving with maximum settings in both programs. FastStone Photo Resizer also results in reduced file sizes over PS.
alot of that is the massive meta tags that photoshop puts into the pictures.
you shoudl try optiminzg the jpgs with somthing like mozjpeg. that strip out meta data and uptimisedsthe huffman compression stages.
you'll see a drop in size with no change in the pixel data.
 
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