Responsive Images: How they Almost Worked and What We Need

by Mat Marquis

77 Reader Comments

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  1. Mat’s essay mentions that the work-around hacks by his team and others fails when ‘newer’ (and unmentioned) browsers may, upon parsing a link or via markup, proactively download things.

    Work-arounds that rely on cookies and/or script-replacement may see issues, as the Boston Globe does now.

    A semantic note: a pre-_fetch_ is, at present, a request to pre-load resources, on an individual basis. One HTML file, one image, etc. I do not believe any browsers parse said HTML and load its referenced resources when in this mode. A pre-_render_, on the other hand, loads a page and all its content, but keeps it hidden. At the moment, “it only happens on Chrome”: . These are different from a DNS-pre-fetch, which simply resolves IP addresses for faster browser-to-server first-contact.

    When Firefox pre-fetches content (at the behest of the referrer page’s markup), it sends the following header with the request: X-moz: prefetch

    Safari does similarly, using: X-Purpose: preview. According to “this ticket”: , Chrome does, too.

    For pre-rendering, Chrome does not send any header whatsoever to the client. Instead, one must use the “Page Visibility API”:, in JS.

    What to do

    In most circumstances, a pre-fetch ought not to be initiated on a mobile browser without a lot of forethought. If you think said mobile browsers will hold to that idea (and I hope you’re right), you can watch for the HTTP pre-fetch headers, and make sure to load the full-size image for that request.

    The various browsers need to be lobbied for an opt-out, too. While at the time, I thought the “effectively-mandated”: IE-8 X-UA-Compatible header was horrendous, at least it put the capacity for control in the hands of an individual site. As browser-makers add whiz-bang features to their products, we as site builders need mechanisms to deliberately opt-out of those that would negatively affect user experience.

    The DNS-prefetch implementors did this right. The X-DNS-Prefetch-Control header allows a site-owner to opt-out gracefully.

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  2. Remember the early days of the web, watching interlaced GIFs load, bit by bit, as though looking through a window whose blinds were being slowly opened? No? Get off my lawn.

    Through a different methods, progressive image loading is supported by PNG and JPEG, as well. I don’t see anything regarding the new kid, WebP.

    Imagine, for a moment, a single image file that would look correct on browsers of any size and connectivity. In theory, this is possible when interlaced images are handled properly.

    A 800×800px image has four times as many pixels as its imaginary mobile-sized counterpart, which clocks in at 400×400px. Now imagine this larger image is a progressive image. In order to display this image well at the smaller, mobile size, one could theoretically load only one-quarter of the original image.

    (Yes, I know there are overheads to progressive images. An image file, when saved progressively, is usually slightly larger than a non-progressive file. “There can be no progress, no achievement without sacrifice…“ -James Allen)

    That sounds like a good future, doesn’t it? Because the browser understands the rendering intention (size), it can load only as much of the image as it needs to display it well. A really intelligent browser would consider this a partial download, and remember the file offset in case it wanted an even bigger image and decided to resume download.

    The best of all worlds, without new markup.

    Now if only someone would support JPEG2000, which is supposed to do an even better job at interlacing.

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  3. wessman: Oh dude, that is some serious knowledge you’ve just dropped. It’s very possible this means our original responsive images script is still viable. Granted it’s still a workaround for a pretty fundamental issue—and in no way changes my upcoming letter to Santa/the WHATWG—but this is absolute gold.

    If you should ever find yourself in Boston, sir, I owe you a beer.

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  4. It seems to me that any technique that requires web developers to implement additional complex markup is only ever going to have a low takeup.  If a device can only render a low res image it should probably make that clear in the headers of its request, and then web servers can scale images before sending them.  This kind of approach can be implemented transparently and would work with existing sites and markup.

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  5. Detective work is not an easy thing to accomplish, but the image element replaced with an audio/video like approach is brilliant. Not only do we need to detect for resolution/screen size for imagery, but also scripts and libraries that are not needed for certain devices.

    The Filament Group implemented EnhanceJS which is brilliant and totally useful for detection, but as of today there isn’t a ton of interest on their google code page. Also currently Modernizr also wont detect the max-device-width media query for its load property.

    Too bad these options and solutions are not bringing in attraction as we seemed to be concerned with image sizes rather than the whole ball of wax. Thanks for the deep thoughts and share :)p

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  6. In keeping with new media tags, why not just “<image>”?

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  7. Hey Mat, really good article on image options for mobile first development. I was very curious on how we, as designers and developers, could get in on the conversations with WHATWG and the like about implementing better options for images in HTML markup.

    Is there an easy way to join the conversation and would it be helpful to have more people in on it?


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  8. jkane001: We thought about that, actually—it turns out <image> can be used interchangeably with <img> in some older browsers.

    Like I mention in “this comment”: , I’m not 100% in love with “picture” for the new element—but, y’know, it’s a theoretical work in progress.

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  9. Guys, thank you very much for all the feedback! This is the only way to get this topic in the right direction and to get a working code.

    As a result I’ve spend some hours reading, analyzing the comments and sorted out. This is what is valuable feedback (sorry, I sorted out all the duplicates of code-element-names etc.): “See my updated article”:

    @Mat: What do you plan on the WHATWG list? I’d recommend moving the topic forward in W3C’s “public-html”-list where the topic is already in list here: “[whatwg] add html-attribute for responsive images”:
    So please don’t open up a new duplicate while another topic has already run through the WHATWG lists and moved to W3C’s list. Thanks!
    If you have questions, please don’t hesitate to contact me.


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  10. I haven’t read all of the responses here but I’ve been thinking over this. I would love to see a ‘path’ option that could be included as part of the CSS and be a distinction in the media query. So for a normal 960 or larger view you could have img path:fullsize; and that could switch for tablets and mobile depending on the media query to be path:tablet; or path:mobile; as needed which would pull the appropriate image source from the folder that is being called. It is a bit of work easily solved through resizing actions. Much less work than what is currently needed with video and the various formats that are needed to degrade properly.

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  11. @my ad: As far as I understood you’re talking about a solution to solve the responsive image problem inside CSS, too. This is something you can read in my proposal here: “see blog article”:
    I like the idea of being responsive in either way — informational elements in HTML, non-informational/styling-elements in CSS.

    Is that what you’ve been thinking of? If not, please clarify so we can sort this out.

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  12. @anselmh Yes, I would like to see the solution come through CSS as I think it is the best way to approach it for the long term. Adding in javascript workarounds seems messy to me as we look into the future and think it only serves as a crutch to the bigger issues.

    Thinking this through over the morning I’ve found various issues with my original thought and what could be solutions or could lead to complications. Below is a breakdown of how it could work changing around how a few things are currently structured.

    Through the img tag you would nolonger specify an full path to the asset as it is currently structured. ie, img src=“folder/logo.jpg”

    This would be handled through the CSS file using ‘path’ or some other specifier. So the document would now look as follows.


    img src=“logo.jpg”


    img { path: desktop; }

    This would lead the logo.jpg to be pulled from an image folder named ‘desktop’ and retrieve the full size asset.

    This can be changed using media queries to pull the different size assets from a different source folder as follows.

    @media screen and (max-width: 480px) {
      img { path: mobile; }

    If a person doesn’t like to have all images coming out of one directory you could pull images out of various folders through a class element. { path: company; }
    img.products { path: products; }

    resulting in – img class“company” src=“logo.jpg”

    and so on.

    You could specify where the assets are coming from depending on the different scenarios that are being designed for. As we look ahead screen sizes and resolutions are going to keep multiplying and we’ll very soon be taking into account televisions adding more complexities.

    Using this approach front end devs that are not concerned with responsive design can still use the traditional path structure without specifying path: ; in the CSS – img src=“folder/logo.jpg” and it would work as expected.

    The part that I’m not fond about is having to create various sizes of the same image however this also opens up a number of design opportunities as you can customize images depending on which display it is being viewed on.

    I see this providing designers a lot of potential to customize how a page would look and deliver images to that specific device instead of needing to use the same image for every instance and simply scaling it.

    This approach keeps the current responsive principles and allows for additional customization but my favorite part of this solution is it only adds one piece of code and leaves the rest of the styled elements via CSS as is.

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  13. I should clarify when I say ‘I would like to see the solution come through CSS’. Ideally the best solution would be native HTML enhanced by CSS. The HTML would be a fall back to an enhanced CSS solution.

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  14. I still think that that there should be an all emcompassing <media> tag that would allow the browser to gracefully degrade from <video> to <img> to any other element you could use for that area (and dependent on a standard media attribute). It seems like the video tag is only scratching the surface of the power of graceful degradation via HTML, why stop there? What about using a shorter headline or paragraph text if the viewport is smaller? Why not give us the option of giving a html alternative for an image versus relying on basic text in an alt tag?

    Too many tags, not enough scalability.

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  15. As our mobile-large screen responsive evolution presses on at warp speed… those on the crest of the wave are held back by seemingly simple technological hurdles.  We have to remember the large screen in the equation as brand channels will begin to immerge with one feed -> mobile-large screen. 

    Our frustrations are but a small slice in time.  What may seem like a solution today, may be an obstacle in only a matter of months.

    I so love your suggested solution.  It absolutely makes sense – today… and is evolution enabled.

    Well said and good luck in persuading the powers that be to enable these markup improvements.

    Responsive image nirvana.

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  16. Commenter #11 asked about this but I didn’t see a response from Mat. Any thoughts on this approach?

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  17. This is excellent article in the way it expresses what developers go through in battling how things change and evolve on the web and whereby most designers don’t ever really get the intricacies that developers have to deal with.

    I think it’s not enough for designers to just study design, they need to study structure and code as well. The reverse is equally important but I think there’s plenty of momentum lately for developers to understand the importance of great design. Full disclosure, as a former developer, I may be biased in who I think needs to work harder. :)  Nevertheless, nice article!

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  18. I’d like to propose a new tag: IMG


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  19. I think it’s a good method. Not all people can think of ideas as great as the ones mentioned above.

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  20. fantasy, coins, gold, silver, copper, D&D, role, playing, currency, money, campaign

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  21. All these approaches put to much of a burden on developers! They’re clunky, prone to breakage and force the use of more markup. But maybe worst of all they force you to define fixed dimensions where you switch the image and to maintain multiple versions of the image!
    I’m really quite astonished that no one so far has mentioned that JPEG 2000 together with the JPIP protocol handles this use case already… Store the image on the server in the maximum resolution you want to offer, but just download a size appropriate for the user’s display. Open source JPIP servers are available… (Djatoka for instance can serve ‘regular’ formats from a jp2 file, providing a fallback.) Better native support for JPEG 2000 in browsers would be nice of course.

    Some experiments need to be done on how best to use inline JPEG 2000 for responsive images. I suppose one approach could be sending a scaling factor (or max size) with a cookie and do some URI rewriting on the server side to get the desired image size. CSS can still be used to downscale the image for a perfect fit. It’s not optimal, but the main point is to just work with one image and let the server handle the scaling.

    Yes, JPEG 2000 requires encoders/decoders that are complex and more computationally ‘demanding’. But there has to be a tradeoff somewhere.

    And let’s not forget that JPEG 2000 offers many other useful features.

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  22. I wrote the comment above in a hurry and forgot to clarify that of course no browser currently implements the JPIP protocol. However I still think using a JPEG 2000 server over HTTP could be a very interesting method towards solving the problem of responsive images. And it would certainly help push native implementations of the JPEG 2000 standard.

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  23. What about an approach of using the CSS media type to control the image source? No JavaScript involved, but it does assume that mobile devices come up with a media type of handheld. You probably can’t use the img tag, but maybe a div tag. Then again it changes the function of the div tag and is not semantically correct. A change to the markup to support images like videos would still be the best option.

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  24. I’ve been experimenting with this, . I watched the resources as I expanded the window and the different image for the widest display isn’t requested until that CSS is triggered by the window reaching each specified width.  (I cused different images so I could see the change easily).

    No Javascript at all.


    @media screen and (orientation:landscape)  and (min-width:480px){


    @media screen and (orientation:landscape)  and (min-width:1024px){


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  25. I agree, a picture tag was perfect to solve this problem, we have a solution for this, but this solution is not easy to implement, and, at this time, we have to care about many device sizes more and more. Hey W3C, look this post! :P

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  26. @Marc Diethelm: This is entirely the best solution. I’ve written about it as the “perfect solution” in my blog post. The problem is, that JPEG2000 isn’t that good of a format for graphics. So we would need ideally WebP/WebM to be able to progressively download and serve responsive images. Until that is implemented in all browsers (haha!) you will still need another approach, so that’s why we proposed the HTML5 solution for interim.

    JCOELHO, yeosteve: A CSS only solution wouldn’t work as it’s not semantic and doesn’t work valid. It still should be possible to do via CSS for non-semantic (styling/layout) purposes, too. Mailing list of W3C didn’t care about this very much ;)

    @Anserson Schmitt: We (Mat and I) are currently discussing on WHATWG lists and if we have a solution over there, it will move to the W3C list. So be sure we do our best W3C cares about this problem :)

    @ NatCk: is only a polyfill solution and uses some technique not very good for a standard-solution.

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  27. Since we’re talking about changing the browser’s behavior anyway, why not actually make it offer up the information to properly solve this problem server-side?  Let’s have the browser send the information that is available to the “css media queries”: in the HTTP GET request headers caused by the one-and-only whatever.png tag or CSS url(“whatever.png”). 

    To wit:
    X-Media: “screen color:24 resolution:120dpi orientation:portrait device:640×480 viewport:500×300”

    (obviously, the aspect-ratio and device-aspect-ratio can be computed, color-index seems meh)

    The nice thing about this is that it is really up to the user-agent’s current needs to determine what should be displayed, thus what should be requested.  If someone zooms in, the user-agent can ask for a bigger version.  If they switch to print view, we can ask for the monochrome version in higher DPI and all is warm and fuzzy. If the server doesn’t care, it serves up the one-true-image. If the server cares, it can serve specific versions.  Cache logic can be driven by the standard content-negotiation logic (and left non-cached until it is).

    The best part of ALL of this is that the CSS can just reference an image, the html can just include a img tag, etc… and the browser’s request can be driven by what it knows already about the size/placement/device of the image.

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  28. Use JavaScript stylesheet manipulation. All responsive images should be rendered in an <img> with a token classname, such as ‘responsive’, and should have fallback ‘src’ value. In <head>, JS will add a stylesheet rule to ‘display:none’ all such elements (to avoid requesting the wrong image resource), then will determine the appropriate screen size category. Script block at the bottom of the page will alter ‘src’ values of all responsive <img>s according to screen size category, per some naming convention, and then update stylesheet rule to ‘display:inline’ all such elements.

    This may cause flicker, more noticeable when HTML is generated/delivered slowly. This can be mitigated by encapsulating the responsive <img> in some server-side component that also emits a script block right after each <img> to do the ‘src’ attribute manipulation and displaying.

    The ‘resize’ event will be handled to perform this logic in case different images need to be re-rendered (can be short-circuited if new image would have lower quality).

    If UA doesn’t support JS or doesn’t support stylesheet manipulation, there will be flicker or simply the fallback content is rendered.

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  29. Is there a reason why you can’t just use images as the source in the video tag with the image MIME type, as in the following example??

          <source src=“high-res.jpg” media=“min-width:800px” type=“image/jpeg”>
          <source src=“low-res.jpg” type=“image/jpeg”>


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  30. This one is an inspiration personally to uncover out rather more related to this subject. I must confess your information extended my sentiments as well as I am going to proper now take your feed to stay updated on every coming blog posts you would possibly possibly create. You are worthy of thanks for a job perfectly carried out!

    “Web Design Company”:
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  31. What do you think of my responsive images proposal?

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  32. The “Responsive Content”: jQuery plugin is an approach which works in a “coarse grained” way, ajax-loading an entire HTML fragment into the page, given current window width (and pixel density). It can be used to tell the server to supply appropriately sized image src URLs etc.

    It’s a fork of Github’s Pjax loader. It does not rely on User Agent or cookies – just window width.

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  33. Correstion. Correct url:

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  34. But, Do I Need Responsive Website For Growth of My Business?

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  35. How do would you appreciate these 2 solutions to download only the small images when needed (Smartphone, iPhone, Android)
    1) Use $_SERVER(‘HTTP_USER_AGENT’) in the server script to detect that it is not a PC
    2) Have a main page that detects the screen size and pass it in the URI for subsequent pages.

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  36. A great solution to <video>-like functionality. Wondering if a similar functionality can make <img> element accept multiple sources like video does.

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  37. @dojo4 we developed something similar, but make the choice about which images to download not based on screen width, but on bandwidth –

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