Browser makers had been settling down on one way to pick the best images for everything from tiny mobile phones to Apple Retina displays, but a new proposal has muddied the waters again.
Last week, it seemed like browser makers were about ready to settle on an idea called srcset to grapple with the tricky task of fetching the best images to show on today's wide variety of screen types.
This week, the issue is up in the air with the arrival of a new possibility called srcN. And it also handles another situation called "art direction," the idea of delivering a cropped image so people seeing it on small screens aren't saddled with inconveniently small details.
On Friday, Google engineers Tab Atkins and John Mellor proposed srcN, which is so named because it draws images from a number of sources depending on different circumstances. They believe it's better than srcset and another contender, the picture element. Mozilla's Marcos Carceres drew attention to it and on Sunday said on Firefox's bug-tracking system that instead of last week's plan to start building srcset support into Firefox, "We should see how srcN pans out before proceeding."
Srcset first arrived in August in WebKit, the open-source foundation used to build Apple's Safari and that was the source for Google's Blink engine within Chrome. Chrome support arrived in August, though also only in a testing mode. Mozilla's support gave srcset important new momentum, so Carceres' opinion about holding back is significant.
It may sound like abstruse discussions, but the technology will have a big effect on millions of ordinary people who use the Web. Helping a browser pluck the right images off a server means screens like Apple's Retina models with high pixel density would show crisp, high-resolution photos. It also means that small screens on phones wouldn't waste network resources and time downloading big images.
There are ways to handle the variety of screens today, but they often involve extra programming to handle all the cases. Making it easier would mean programmers would be more likely to embrace the technology.
Mellor on Sunday detailed the reasoning behind srcN, which he and Atkins created after a meeting earlier this month of the W3C's Responsive Images Community Group that's tackling the issue.
In an e-mail on Sunday to the Blink mailing list, Mellor also called for a pause before distributing srcset in Chrome: "Could I throw a spanner in the works and suggest that we hold off shipping this quite yet?"
Yoav Weiss, a Web developer who's been working to add srcset and another alternative called
Chrome team member Adam Barth sounded a little leery about the idea, asking, "Are other vendors interested in srcN? It seemed like we were on the verge of critical mass for srcset..."
Carceres responded: "Mozilla is interested, but I need to bounce it around internally a bit more. We are not a big fan of srcset, but it seemed like it provided a good evolutionary path. srcN kinda changes the game a bit so we need a few weeks to poke at it before we make a decision on how we are going to proceed."