Get the LEAST from your images

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@deanohume Getting the LEAST from your images @rposbo

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Images are awesome

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But they aren’t great for web performance

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in fact....

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They are greedy Stylesheets, HTML, etc Images JavaScript

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Images are the biggest part of a web page Stylesheets, HTML, etc Images 60% JavaScript

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The average web page makes 56 image requests per page * Source: HttpArchive.org

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42% of all websites make over 50 image requests per page * Source: HttpArchive.org

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The Web wouldn’t be the same without images

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...So

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We need to Make more efficient use of requests

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We need to Make more efficient use of requests & Reduce the size of the images

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We will look at

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We will look at - Well known methods for reducing the size of your images and http requests

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We will look at - Well known methods for reducing the size of your images and http requests - Some lesser known methods

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We will look at - Well known methods for reducing the size of your images and http requests - Some lesser known methods - The future of images on the web

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The Basics

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Things everyone should be doing

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Things everyone should be doing

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Things everyone should be doing Image optimization

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Things everyone should be doing Image optimization Spriting images

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Things everyone should be doing Image optimization Spriting images Lazy loading

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Image Optimization tools

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Offline tools

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- Image Magick - Jpeg Optim - Jpeg Tran Jpeg

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- Image Magick - Jpeg Optim - Jpeg Tran Jpeg - Image Magick - Png Crush - Png Out Png

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- Image Magick - Jpeg Optim - Jpeg Tran Jpeg - Image Magick - Png Crush - Png Out Png - Image Magick - Gifsicle Gif

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Online tools

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Online tools smushit.com kraken.io

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Automate it!

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kraken.io Optimisation APIs

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kraken.io punypng.com/api Optimisation APIs

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kraken.io punypng.com/api webresizer.com Optimisation APIs

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The Baseline

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Sprites

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Take lots of little images

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..and combine into one image

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.norwegian_flag { width: 120px; height: 75px; background:url('/images/sprites/flag-sprite.png'); background-position: -240px -84px; }

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1 request

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1 request many images

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Recommendations - No whitespace

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Recommendations - No whitespace - Optimize & cache

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Recommendations - No whitespace - Optimize & cache - Aim for similar palettes

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Lazy Loading

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Lazy Loading - Only load what the user sees

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Lazy Loading - Only load what the user sees - Load images as the viewport moves

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Lazy Loading - Only load what the user sees - Load images as the viewport moves - Reduce unnecessary HTTP requests

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Loads every image

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12x Requests

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3x Requests

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Benefits Reduced HTTP requests

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Benefits Reduced HTTP requests A lot of users don’t scroll entire page

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Benefits Reduced HTTP requests A lot of users don’t scroll entire page Faster initial page load times

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Moving on..

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WebP Images

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WebP is a new image format

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WebP is a new image format newish

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They’re great because: 26% smaller than PNGs

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They’re great because: 26% smaller than PNGs 25-35% smaller than JPGs

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They’re great because: 26% smaller than PNGs 25-35% smaller than JPGs Image quality isn’t affected

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Which means smaller web pages!

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Jpg WebP

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48.9 KB ?

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48.9 KB 12.6 KB

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75%

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280 Kb ?

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280 Kb 50 Kb

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83%

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WebP has it’s downsides

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WebP has it’s downsides No IE support

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WebP has it’s downsides No IE support No FireFox support

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WebP has it’s downsides No IE support No FireFox support No iOS support

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Support is growing!

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How can I use it?

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Use it today https://developers.google.com/speed/webp/ WebP converter tool

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Use the WebP tool Specify compression

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Use the WebP tool Specify compression Specify sharpness & size

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Use the WebP tool Specify compression Specify sharpness & size Available for Win, Mac & Linux

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JavaScript Shim https://github.com/antimatter15/weppy

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JavaScript Shim https://github.com/antimatter15/weppy Client Side http://www.stucox.com/blog/using-webp-with-modernizr/

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JavaScript Shim https://github.com/antimatter15/weppy Client Side http://www.stucox.com/blog/using-webp-with-modernizr/ Server Side http://tinyurl.com/BlogWebP

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Give it a go! tinyurl.com/LeastWebP

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Compressive Images

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Compressive Concept..

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Compressive Concept..

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Compressive Concept..

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Compressive Concept..

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Compressive Concept..

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Compressive Concept..

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Compressive Concept..

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Compressive Concept..

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YDN says... “Don't Scale Images in HTML. Don't use a bigger image than you need just because you can set the width and height in HTML. If you need: My Cat

then your image (mycat.jpg) should be 100x100px rather than a scaled down 500x500px image.”

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Google says.. “Specify dimensions that match those of the images themselves. Don't use width and height specifications to scale images on the fly. If an image file is actually 60 x 60 pixels, don't set the dimensions to 30 x 30 in the HTML or CSS. If the image needs to be smaller, scale it in an image editor and set its dimensions to match”

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Rationale 1. You don't want to download more bytes than necessary

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Rationale 2. Browsers are bad at resizing images

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Don’t download more bytes

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Don’t download more bytes * From Daan Jobsis’ wonderful article @ http://tinyurl.com/retinarev

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Don’t download more bytes Big image low quality = GOOD Small image high quality = BAD

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Browsers are bad at resizing

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* From Roy Tanck’s interesting study @ http://tinyurl.com/browserscaling Browsers are bad at resizing 150 images: 50 x 24bit pngs 50 x jpeg 50 x 8bit gif One page: images displayed at 100%

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Browsers are bad at resizing 150 images: 50 x 24bit pngs 50 x jpeg 50 x 8bit gif * From Roy Tanck’s interesting study @ http://tinyurl.com/browserscaling One page: images displayed at 100% Duplicate page: images scaled to 61.5%

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* From Roy Tanck’s interesting study @ http://tinyurl.com/browserscaling No difference whatsoever Browsers are bad at resizing

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Is it good?

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Is it good?

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Support for Compressive Images

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Support for Compressive Images Chrome

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Support for Compressive Images Chrome All of them

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Support for Compressive Images Chrome All of them Opera

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Support for Compressive Images Chrome All of them Opera All of them

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Support for Compressive Images Chrome All of them Opera All of them Firefox

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Support for Compressive Images Chrome All of them Opera All of them Firefox All of them

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Support for Compressive Images Chrome All of them Opera All of them Firefox All of them IE

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Support for Compressive Images Chrome All of them Opera All of them Firefox All of them IE All of them

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Support for Compressive Images Chrome All of them Opera All of them Firefox All of them IE All of them

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Support for Compressive Images Chrome All of them Opera All of them Firefox All of them IE All of them* at least I think so...

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Got ? Got Compressive

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Give it a go! tinyurl.com/LeastCompressive

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Data URIs

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“The fastest HTTP request is the one not made.”

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Every image in a web page is a new HTTP request

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Data URIs are different

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Data URIs are embedded as a Base64 encoded string

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Data URIs Embedded in a web page

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Data URIs Embedded in a web page No HTTP request is made

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Data URIs Embedded in a web page No HTTP request is made Faster load times

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Data URIs Embedded in a web page No HTTP request is made Faster load times* *Sometimes

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Support is great So....what’s the catch?

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- Some browsers only support Data URIs up to a certain size

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- Some browsers only support Data URIs up to a certain size - Base64 encoded strings are actually around a third larger than the original image size

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- Some browsers only support Data URIs up to a certain size - Base64 encoded strings are actually around a third larger than the original image - Need to re-encode on every change

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- Some browsers only support Data URIs up to a certain size - Base64 encoded strings are actually around a third larger than the original image - Need to re-encode on every change - Consume battery and CPU on mobile devices

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Don’t worry!

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- Images less than 32K - Great for icons Use it for:

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Give it a go! tinyurl.com/LeastDataURI

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The Future?

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The Future?

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The right image for the user

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The right image for the user

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srcset HTML attribute

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picture HTML Element

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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picture + srcset

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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Lookit the cuuute kitty awwww

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HD SD Tiger & Cat: http://www.flickr.com/photos/doug88888/ Kitten: http://www.flickr. min-width: 45em tiger-HD.jpg 2x min-width: 18em cat-HD.jpg 2x min-width: 18em cat.jpg 1x kitten.jpg 1x kitten.jpg 2x min-width: 45em tiger.jpg 1x

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image-set() CSS4 function

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background-image: image-set( "cat.png" 1x, "cat-HD.png" 2x, "cat-print.png" 600dpi );

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background-image: image-set( "cat.png" 1x, "cat-HD.png" 2x, "cat-print.png" 600dpi );

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background-image: image-set( "cat.png" 1x, "cat-HD.png" 2x, "cat-print.png" 600dpi );

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background-image: image-set( "cat.png" 1x, "cat-HD.png" 2x, "cat-print.png" 600dpi );

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@media all{ #pictureElement{ background-image: image-set(kitten.jpg 1x, kitten-HD.jpg 2x); } } @media all and (min-width: 45em){ #pictureElement{ background-image: image-set(tiger.jpg 1x, tiger-HD.jpg 2x); } } @media all and (min-width: 18em){ #pictureElement{ background-image: image-set(cat.jpg 1x, cat.jpg 2x); } }

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Your favourite?

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Srcset Image-set Picture Element Multiple image dimensions Multiple image resolutions Reduces HTTP requests