{"id":3421,"date":"2019-01-08T00:00:00","date_gmt":"2019-01-08T00:00:00","guid":{"rendered":"https:\/\/www.litmus.com\/blog\/understanding-retina-images-in-html-email\/"},"modified":"2023-07-11T15:58:39","modified_gmt":"2023-07-11T19:58:39","slug":"understanding-retina-images-in-html-email","status":"publish","type":"post","link":"https:\/\/www.litmus.com\/blog\/understanding-retina-images-in-html-email","title":{"rendered":"Understanding Retina Images in HTML Email"},"content":{"rendered":"<p>Apart from the onslaught of screen sizes, the mobile revolution introduces another interesting challenge for email designers: high-DPI displays. Often called Retina displays (a term coined by Apple), they can enhance any email campaign\u2014or give your subscribers a less-than-stellar email experience.<\/p>\n<p>In this post, learn exactly how high-DPI displays work and what that means for email designers and marketers.<\/p>\n<h2>When did Retina displays get introduced?<\/h2>\n<p>Back in 2010, Apple released the iPhone 4. Among other hardware improvements, the iPhone 4 featured what Apple called a Retina display. Apple\u2019s Retina display was one of the first high-DPI, or high dots per inch, displays mass-produced for consumers.<\/p>\n<p>On device screens, DPI refers to the number of pixels a manufacturer can fit into an inch of screen. The higher the DPI, the more detailed and clear images and text on that screen appear.<\/p>\n<div style=\"background-color: #d7f1ff; border: 1px solid #5babe3; border-radius: 3px; color: #5babe3; line-height: 1.5; margin: 0 0 30px 0; padding: 20px;\">Apple refers to their high-DPI displays as Retina displays since, in theory, the DPI is so high that the human eye can no longer distinguish between individual pixels on the screen. While \u2018Retina display\u2019 is an Apple brand name, the term \u2018retina\u2019 is often used to describe high-DPI displays from other manufacturers. Likewise, retina is commonly used to refer to images optimized for high-DPI displays, which you\u2019ll learn about below.<\/div>\n<p>Although Apple was the first to introduce the Retina display to a mainstream audience, it wasn\u2019t long before other device manufacturers hopped on board. While most companies started with smaller devices like phones, retina screens can now be found on tablets, laptops, and even desktop computers like Apple\u2019s massive 27-inch Retina 5k iMac.<\/p>\n<h2>Why does email need retina images?<\/h2>\n<p><a rel=\"noopener\" href=\"https:\/\/www.litmus.com\/blog\/subject-line-tests-and-tips\/\" target=\"_blank\" rel=\"noopener\">Subject lines<\/a>, copy, and cadence all play an important part in looking good to subscribers, but visuals draw people to an email campaign first. After opening an email, our eyes move to the design and imagery before we start reading any copy or tapping <a rel=\"noopener\" href=\"https:\/\/www.litmus.com\/blog\/email-cta-copy-tips\/\" target=\"_blank\" rel=\"noopener\">calls-to-action<\/a>.<\/p>\n<p>If you\u2019re not accounting for high-DPI displays, you run the risk of looking careless to subscribers. Because of the way high-DPI displays work, non-optimized images end up looking blurry and pixelated on retina screens. Here\u2019s an example:<\/p>\n<figure id=\"post-13372 media-13372\" class=\"aligncenter\"><img decoding=\"async\" class=\" shaded\" src=\"https:\/\/www.litmus.com\/wp-content\/uploads\/2020\/04\/retina-comparison.jpg\" alt=\"Non-Retina v. Retina Images\" \/>\n<figcaption>Non-Retina v. Retina Images<\/figcaption>\n<\/figure>\n<p>As users grow accustomed to retina screens, they expect text and images to appear crisp and clear. If you\u2019re not optimizing your images for high-DPI screens, those users see a degraded email design, which can lead to equally degraded trust in your brand.<\/p>\n<figure id=\"post-22540 media-22540\" class=\"aligncenter\"><\/figure>\n<h2>How to use retina images in email<\/h2>\n<p>How exactly can you optimize images for retina screens? Forturnately, it&#8217;s quite simple.<\/p>\n<p>Roughly speaking, high-DPI displays have twice as many pixels per inch than their traditional counterparts. For images to look good on those screens, they need to be twice as large. When they\u2019re scaled down in the email, there are more pixels for retina screens to display.<\/p>\n<p>Here&#8217;s an example.<\/p>\n<p>In our emails, we include the Litmus logo at the top. Using HTML, it\u2019s sized so that it displays at 130 by 48 pixels. If we created and saved the logo image at that size, subscribers would see a blurry mess on retina screens:<\/p>\n<figure id=\"post-13367 media-13367\" class=\"aligncenter\"><img decoding=\"async\" class=\" shaded alignnone\" src=\"https:\/\/www.litmus.com\/wp-content\/uploads\/2020\/04\/retina-images-logo-blurry.jpg\" alt=\"Retina Images in Email - Blurry\" width=\"753\" height=\"153\" \/><\/figure>\n<p>To keep the logo crisp, we simply create an image at a larger size. In this case, the image file is 276 pixels by 102 pixels, but anything that\u2019s at least double the intended display size works. Then, in our HTML, we use the original, intended display size in the width and height attributes to scale the larger image down:<\/p>\n<pre><code style=\"background: #333; color: #fff; margin: 20px 0 30px 0;\">&lt;img alt=\"Litmus\" src=\"logo@2x.png\" width=\"130\" height=\"48\" style=\"font-family: sans-serif; color: #ffffff; font-size: 20px; display: block; border: 0px;\" border=\"0\"&gt;<\/code><\/pre>\n<p>On high DPI displays, we get beautiful, crisp, retina images.<\/p>\n<figure id=\"post-13368 media-13368\" class=\"aligncenter\"><img decoding=\"async\" class=\" shaded alignnone\" src=\"https:\/\/www.litmus.com\/wp-content\/uploads\/2020\/04\/retina-images-logo-crisp.jpg\" alt=\"Using Retina Images in Email\" width=\"753\" height=\"153\" \/><\/figure>\n<h3>Using Retina Images in Outlook<\/h3>\n<p>Some versions of Microsoft Outlook still display the retina images at their full size, despite the explicit sizes set by the width and height attributes. To get around this, you can include a max-width rule in the style attribute of the image.<\/p>\n<p>In the example below, we use the width attribute (no height attribute) and the max-width to get retina images working across all email clients.<\/p>\n<pre><code style=\"background: #333; color: #fff; margin: 20px 0 30px 0;\">&lt;img alt=\"Litmus\" src=\"hero@2x.png\" width=\"600\" style=\"width: 100%; max-width: 600px; font-family: sans-serif; color: #ffffff; font-size: 20px; display: block; border: 0px;\" border=\"0\"&gt;<\/code><\/pre>\n<p>You&#8217;ll notice the inclusion of a width style set to 100%. This is a handy trick for making images responsive across different screen sizes. On larger screens, the max-width rule will kick in to constrain the image size, while on smaller screens they will fill 100% of the screen\u2014or container\u2014width.<\/p>\n<h3>Can background images be retina images?<\/h3>\n<p>You can use retina images as <a rel=\"noopener\" href=\"https:\/\/www.litmus.com\/blog\/the-ultimate-guide-to-background-images-in-email\/\" target=\"_blank\" rel=\"noopener\">background images<\/a>. The implementation is slightly more complex, but the principles are the same.<\/p>\n<p>But note that this approach won&#8217;t work everywhere. For retina background images, you should use the background CSS property instead of the background HTML attribute on something like a table cell.<\/p>\n<pre><code style=\"background: #333; color: #fff; margin: 20px 0 30px 0;\">&lt;td style=\"background:url(img-x2.jpg) center\/cover;background-image:url(img-x2.jpg);background-size:100%;background-size:cover;\"&gt;<\/code><\/pre>\n<p>The background is set using both the shorthand property and using individual CSS background properties to account for some quirks in Gmail and Android clients. T<a rel=\"noopener\" href=\"https:\/\/litmus.com\/community\/discussions\/4931-using-retina-images-as-background-images\">his Community discussion<\/a> has a great overview of the techniques available to designers looking for gorgeous background images on high-DPI displays.<\/p>\n<h2>Considerations before using retina images<\/h2>\n<p>Doubling the size of your images helps ensure that they display beautifully on retina screens, but this technique is not without its drawbacks.<\/p>\n<p>As we increase the dimensions of an image, the file size increases, too. That can cause <a rel=\"noopener\" href=\"https:\/\/www.litmus.com\/email-testing\/\" target=\"_blank\" rel=\"noopener\">an email to load slowly<\/a>.<\/p>\n<p>And, not every campaign needs retina images. If you&#8217;re using a lot of images in your campaign, or images that are really large, using standard, non-retina images may help provide a better user experience since the images will be quick to download and display in your campaign.<\/p>\n<p><strong>If you do need to use retina images, there are two techniques to help avoid bloated file sizes.<\/strong><\/p>\n<p>The first\u2014and more complicated\u2014is to use something called compressive images. These are images that are saved at huge dimensions, but very low quality settings.<\/p>\n<p>Most image editing programs allow you to set the quality at which images are saved. In Photoshop, for example, you can adjust the quality of a JPEG using a simple slider:<\/p>\n<figure id=\"post-13370 media-13370\" class=\"aligncenter\"><img decoding=\"async\" class=\" shaded alignnone\" src=\"https:\/\/www.litmus.com\/wp-content\/uploads\/2020\/04\/retina-images-quality-settings.png\" alt=\"retina images quality settings\" width=\"730\" height=\"249\" \/><\/figure>\n<p>To create a compressive image, design the image at something around four times the intended size and save it at an extremely low quality setting. While the image looks terrible when viewed at full-size, after it\u2019s scaled down to its intended size in an email, the artifacts shrink down and go unnoticed. And the low quality settings ensure that your file size is kept to a minimum.<\/p>\n<p>The second way to keep file sizes in check is to use a dedicated program to further compress your images after saving them. Applications\u2014many of them free\u2014exist for every operating system that allow you to process and compress images after they are created.<\/p>\n<p>Some of our favorites include <a rel=\"noopener\" target=\"_blank\" href=\"https:\/\/imageoptim.com\/\">ImageOptim<\/a>, <a rel=\"noopener\" target=\"_blank\" href=\"http:\/\/www.jpegmini.com\/\">JPEGmini<\/a>, <a rel=\"noopener\" target=\"_blank\" href=\"https:\/\/tinypng.com\/\">TinyPNG<\/a>, <a rel=\"noopener\" target=\"_blank\" href=\"https:\/\/compressor.io\/\">Compressor.io<\/a>, and <a rel=\"noopener\" target=\"_blank\" href=\"https:\/\/kraken.io\/\">Kraken<\/a>. In most cases, you simply drag and drop\u2014or upload\u2014your images to the program and they compress them. Then, you can upload those optimized images to your ESP or server to include in your retina-ready campaigns.<\/p>\n<h2>\u00a0<\/h2>\n<p>\u00a0<\/p>\n<div class=\"cta\">\n<table>\n<tbody>\n<tr>\n<td class=\"block-1\">\u00a0<\/td>\n<td class=\"block-2\">\u00a0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n\n\n\n\t<div id=\"simple-text-block-block_6245dfe972c00\" class=\"block-simple-text-block alignfull bg-texture \" style=\"background-color:\">\n  <div class=\"container\">\n  \t<div class=\"row\">\n  \t\t<div class=\"col\">\n  \t\t\t<div class=\"copy\">\n  \t\t\t\t  \t\t\t<\/div>\n  \t\t<\/div>\n  \t<\/div>\n  <\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>As high DPI displays become more common the need for retina images increases. Learn how to use retina images in email campaigns.<\/p>\n","protected":false},"author":3,"featured_media":3422,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"tags":[478,468],"blog_category":[53],"class_list":["post-3421","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","tag-design","tag-images","blog_category-tips-resources"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.5 (Yoast SEO v27.7) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>Understanding Retina Images in HTML Email - Litmus<\/title>\n<meta name=\"description\" content=\"As high DPI displays become more common the need for retina images increases. Learn how to use retina images in email campaigns. How to use retina images in email for screens with Retina displays (also known as high-DPI display).\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.litmus.com\/blog\/understanding-retina-images-in-html-email\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Understanding Retina Images in HTML Email\" \/>\n<meta property=\"og:description\" content=\"As high DPI displays become more common the need for retina images increases. Learn how to use retina images in email campaigns. 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