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RE: [public-respimg] <none>

From: Tom Maslen <tom.maslen@bbc.co.uk>
Date: Fri, 5 Jul 2013 08:47:26 +0100
Message-ID: <E64A28D8321E7446B2639224FBA38DC5017E2AEE@bbcxues31.national.core.bbc.co.uk>
To: Anselm Hannemann <info@anselm-hannemann.com>, Marcos Caceres <w3c@marcosc.com>
CC: Ritchie Anesco <info@ritchieanesco.com>, Mohsen Nabiloo Azimi <msnazi@gmail.com>, <public-respimg@w3.org>
Is there a hard limit to how much you can get away with scaling the image up/down before its better to just download an alternative image?

When I made the responsive images solution for m.bbc.co.uk/news we didn't have any data to make a decision about this so I just guessed and made the images scale 100% to fit its containing element, but then get the JS to swap the image out for a better fitted alternative every 30px.


Tom Maslen
Tech Lead
BBC News Visual Journalism

-----Original Message-----
From: Anselm Hannemann [mailto:info@anselm-hannemann.com]
Sent: Thu 7/4/2013 8:45 PM
To: Marcos Caceres
Cc: Ritchie Anesco; Mohsen Nabiloo Azimi; public-respimg@w3.org
Subject: Re: [public-respimg] <none>
On 04.07.2013, at 21:11, Marcos Caceres <w3c@marcosc.com> wrote:

> On Thursday, July 4, 2013 at 8:10 PM, Ritchie Anesco wrote:
>> Hi all,
>> just thought i'll give my 2 cents in regards to this topic, downsampling a large image for the browser to resize definitely has a huge hit on performance if you use css background-size 100%, noticed this whenever you scrolled on tab devices, didn't have much as an effect on inline images.
> Any chance you have a demo handy?

I can confirm this and mentioned this wherever these 'compressive images' solution was appearing. 
The problem with it is, it comes with a high cost: performance is going down massively due to the heavy repaint on resize.
This means when using such techniques on Tablets or not top of the notch smartphones 
your site gets very unresponsive when scrolling. This can be reproduced on nearly every 10" Android Tablet.
And indeed the performance lack is not as heavy on foreground images than on CSS background images.
A demo is hard to reproduce (of course a video would be possible but not very helpful IMO)

Anselm Hannemann | @helloanselm | helloanselm.com

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Received on Friday, 5 July 2013 08:20:01 UTC

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