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Lossy compression for optimizing animated GIFs

How to optimize animated GIFs with lossy compression

Animated GIFs keep getting more and more popular, but they are generally very big files with slow loading times and high bandwidth costs, while the format itself is quite old and not optimized for modern video clips. As developers, you need to allow users to upload their animated GIF files, but you also need to deliver them optimized, which can be a complex, time consuming process.

One option is to convert animated GIFs to videos, another great feature available with Cloudinary which saves on file size and bandwidth (see this blog post for more details), but videos are still not as easy to embed in sites and apps compared to regular image tags, and some browsers and mobile devices still do not support auto playing video files. Another option is to convert animated GIFs to animated WebP files, but this format, introduced by Google and supported on Chrome, is unfortunately not supported by most of the other mobile devices and browsers. Likewise, GIF conversion tools seem to either create files that are too large and of high quality, or smaller files with a bad visual quality.

Another great solution is to perform GIF optimization using a lossy compression technique rather than the lossless nature of the GIF format, allowing you to optimize uploaded animated GIFs to be delivered as smaller files while still looking good. Lossy compression is actually a misnomer for GIFs as the compression algorithms used in GIFs are lossless, and there is no loss of data when compressing this palette-based format (although converting to GIF from other image formats does result in a loss of data due to the 8bit GIF limitation of 256 colors).

The lossiness comes in when the GIF is first filtered or altered so that the image can then compress more efficiently. The loss of data occurs in this filtering phase by increasing redundant patterns along scan lines to subsequently improve the actual compression.

Applying lossy GIF compression

The lossy compression feature is available using Cloudinary's on-the-fly dynamic manipulation URLs, with no need to install any software or to use any computational power on your side because the image manipulation takes place in the cloud. To leverage this capability, and tell Cloudinary to automatically use lossy compression, all you need to do is set the flag parameter to lossy (fl_lossy in URLs).

For example, the following animated GIF named kitten_fighting uploaded to Cloudinary has a file size of 6.3 MB.

Ruby:
cl_image_tag("kitten_fighting.gif")
PHP:
cl_image_tag("kitten_fighting.gif")
Python:
CloudinaryImage("kitten_fighting.gif").image()
Node.js:
cloudinary.image("kitten_fighting.gif")
Java:
cloudinary.url().imageTag("kitten_fighting.gif")
jQuery:
$.cloudinary.image("kitten_fighting.gif")
.Net:
cloudinary.Api.UrlImgUp.BuildImageTag("kitten_fighting.gif")
original non-optimized animated GIF

Enabling the lossy flag, which means adding the fl_lossy parameter to the delivery URL, optimizes the animated GIF to a file size of 2.5 MB. The file still looks good and is now 40% of the original size.

Ruby:
cl_image_tag("kitten_fighting.gif", :flags=>"lossy")
PHP:
cl_image_tag("kitten_fighting.gif", array("flags"=>"lossy"))
Python:
CloudinaryImage("kitten_fighting.gif").image(flags="lossy")
Node.js:
cloudinary.image("kitten_fighting.gif", {flags: "lossy"})
Java:
cloudinary.url().transformation(new Transformation().flags("lossy")).imageTag("kitten_fighting.gif")
jQuery:
$.cloudinary.image("kitten_fighting.gif", {flags: "lossy"})
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation().Flags("lossy")).BuildImageTag("kitten_fighting.gif")
Optimized animated GIF with lossy compression

You can further control the level of lossy compression in the resulting animated GIF by also adding the quality parameter (q in URLs), which has a default value of 80. For example, enabling lossy compression for the kitten_fighting GIF and also setting the quality parameter to 50 results in a file size of 2.1 MB, which means we saved almost 70% of the original file size.

Ruby:
cl_image_tag("kitten_fighting.gif", :flags=>"lossy", :quality=>50)
PHP:
cl_image_tag("kitten_fighting.gif", array("flags"=>"lossy", "quality"=>50))
Python:
CloudinaryImage("kitten_fighting.gif").image(flags="lossy", quality=50)
Node.js:
cloudinary.image("kitten_fighting.gif", {flags: "lossy", quality: 50})
Java:
cloudinary.url().transformation(new Transformation().flags("lossy").quality(50)).imageTag("kitten_fighting.gif")
jQuery:
$.cloudinary.image("kitten_fighting.gif", {flags: "lossy", quality: 50})
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation().Flags("lossy").Quality(50)).BuildImageTag("kitten_fighting.gif")
50% quality lossy animated GIF

Further animated GIF manipulations with lossy compression

The lossy compression feature can be mixed with any of Cloudinary's rich set of image manipulation capabilities to match any graphic design, any dimensions, different devices, different browsers, responsive layouts and more. Lossy compression can also optimize a generated image, so instead of optimizing the original large animated GIF, you can optimize each manipulated or cropped version you would like to display.

For example, the following code generates and delivers a version of the uploaded kitten_fighting animated GIF as follows: Crops the animated GIF to a width of 50% and a height of 80%. Adds another uploaded png image named cloudinary_icon as an overlay. The overlay is resized to a width of 40 pixels, positioned 5 pixels from the top right corner of the animated GIF and is made 40% semi transparent. Lossy compression is applied with a quantity value of 50%.

The size of the delivered file is 765 KB compared to 1.9 MB without using lossy compression (a reduction of 60% in file size).

Ruby:
cl_image_tag("kitten_fighting.gif", :transformation=>[
  {:width=>0.5, :height=>0.8, :crop=>"crop"},
  {:overlay=>"cloudinary_icon", :width=>40, :gravity=>"north_east", :opacity=>40, :x=>5, :y=>5, :crop=>"scale"},
  {:flags=>"lossy", :quality=>50}
  ])
PHP:
cl_image_tag("kitten_fighting.gif", array("transformation"=>array(
  array("width"=>0.5, "height"=>0.8, "crop"=>"crop"),
  array("overlay"=>"cloudinary_icon", "width"=>40, "gravity"=>"north_east", "opacity"=>40, "x"=>5, "y"=>5, "crop"=>"scale"),
  array("flags"=>"lossy", "quality"=>50)
  )))
Python:
CloudinaryImage("kitten_fighting.gif").image(transformation=[
  {"width": 0.5, "height": 0.8, "crop": "crop"},
  {"overlay": "cloudinary_icon", "width": 40, "gravity": "north_east", "opacity": 40, "x": 5, "y": 5, "crop": "scale"},
  {"flags": "lossy", "quality": 50}
  ])
Node.js:
cloudinary.image("kitten_fighting.gif", {transformation: [
  {width: 0.5, height: 0.8, crop: "crop"},
  {overlay: "cloudinary_icon", width: 40, gravity: "north_east", opacity: 40, x: 5, y: 5, crop: "scale"},
  {flags: "lossy", quality: 50}
  ]})
Java:
cloudinary.url().transformation(new Transformation()
  .width(0.5).height(0.8).crop("crop").chain()
  .overlay("cloudinary_icon").width(40).gravity("north_east").opacity(40).x(5).y(5).crop("scale").chain()
  .flags("lossy").quality(50)).imageTag("kitten_fighting.gif")
jQuery:
$.cloudinary.image("kitten_fighting.gif", {transformation: [
  {width: 0.5, height: 0.8, crop: "crop"},
  {overlay: "cloudinary_icon", width: 40, gravity: "north_east", opacity: 40, x: 5, y: 5, crop: "scale"},
  {flags: "lossy", quality: 50}
  ]})
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation()
  .Width(0.5).Height(0.8).Crop("crop").Chain()
  .Overlay("cloudinary_icon").Width(40).Gravity("north_east").Opacity(40).X(5).Y(5).Crop("scale").Chain()
  .Flags("lossy").Quality(50)).BuildImageTag("kitten_fighting.gif")
Animated GIF resized, with overlay added and 50% lossy GIF compression

Summary

Lossy compression for animated GIFs allows you to benefit from both worlds: support animated GIFs, enjoy their simplicity, and still deliver smaller files that look good. Improve your user's experience, save on bandwidth, and all that with zero effort in developing your web sites and apps.

If you need much smaller files and you are ready to embed video files, Cloudinary can auto convert GIFs to videos. Likewise, if you allow your users to upload video files and you want to display animated GIFs instead, you can use Cloudinary to dynamically convert videos to GIFs.

The lossy compression feature for animated GIFs is available to all our free and paid plans. If you don't have a Cloudinary account, you are welcome to sign up to our free account and try it out.

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