Guetzli Installation and Performance report

Guetzli, is a recently Open Sourced JPEG encoder from google. I gave it a whirl to test out the performance/timing for image compression. I’ve tried out PNG->JPG, and JPG only compression with the default quality.

Installation on Ubuntu:

Follow the instruction given on Github Repo:

  • Clone/Download the source code from Github Repo .
  • Install libpng and gflags, using apt-get install libpng-dev libgflags-dev.
  • Run make and expect the binary to be created in bin/Release/guetzli
  • The binary gets created in same directory inside bin/Release/
  • Run vim ~/.bashrc and go to the end of file, add export PATH=~/guetzli/bin/Release:$PATH  and save it, where guetzli is your root folder name.

Performance:

I’ve tested out 5 of each PNG and JPEGs for the conversion on a Digital Ocean single core Ubuntu droplet with 500MB RAM.

PNG Optimisation:

Image Link                      Original Size    Optimised Size  Time

bees.png                          177KB                    37KB              0 m 16.372 s
( Orig | Optimised )

Old_Jewish_man.png*  49KB                    195KB             16 m 5.397 s
( Orig | Optimised )

Render_Homer_8.png   218KB                  146KB             0 m  59.611 s
( Orig | Optimised )

Winter-Is-Coming.png  1.3 MB                 286KB             2 m  26.712 s
( Orig | Optimised )

Himalayas.png               546KB                265KB               4 m 52.428 s
( Orig | Optimised )

JPEG optimisation:

Image Link                                  Original Size    Optimised Size   Time

100_5478.jpg                            189KB                   168KB              2 m 14.152 s
( Orig | Optimised )

Eiffel_Tower_Black_White.jpg  250KB               132KB              0 m 45.584 s
( Orig | Optimised )

taj-mahal-H.jpeg                    473KB                    153KB            2 m 44.823 s
( Orig | Optimised )

Leopard Wallpaper.jpg            699KB                    596KB           11 m 35.742 s
( Orig | Optimised )

Kangaroo.jpg                          270KB                      237KB           3 m 42.517 s
( Orig | Optimised )

* For transparent PNGs, Guetzli automatically inserts a black background while converting them to JPGs, and the image size went 4x higher from 49KB to 195KB and it took 16 minutes for the conversion.

PNG to JPG optimisation is pretty damn good for images without alpha channel aka transparency. Though the time taken for a 177KB file size is 16s, which is way too slow considering if your site have got as low as 500 images, and out of which most of them would be at least above 500KB.

Same goes for JPG to JPG optimisation, a few images are reduced to half, where others got a savings of up to 100KBs. Though the time spent on optimisation is still very high for all of them.

Images for comparison:

PNG to JPG

bees.png original image
Original Image

 

bees.jpg optimised image
Optimised Image

JPG to JPG

taj-mahal-H.jpeg original image
Original Image

 

taj-mahal-H-optimised.jpeg optimised image
Optimised Image

Guetzli is quite time/resource consuming to be implemented in production. I was not able to optimise a 4MB image, as the process was killed every time.

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