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Re: [webkit-dev] Accept- & Content-Resolution headers proposal

From: Nicholas Shanks <contact@nickshanks.com>
Date: Thu, 7 Jun 2007 20:04:54 +0100
Message-Id: <C18D8C19-E981-46ED-BC19-BE5DA72BE67F@nickshanks.com>
Cc: Peter Speck <speck@vitality.dk>
To: ietf-http-wg@w3.org, Web-Kit Dev <webkit-dev@opendarwin.org>
Hello Peter, thanks for the reply. some good ideas there.

On 7 Jun 2007, at 18:48, Peter Speck wrote:

> On 07/06/2007, at 19:18, Nicholas Shanks wrote:
>>> Why force a "next size up" if most UAs prefer a dpi which is  
>>> "close enough"?
>> Do they? I guess it depends. I don't mind spending the bandwidth  
>> for better looking graphics, but someone on a pay-as-you-download  
>> phone most likely would.
> But the UA should be able to tell this in the header, so normal  
> browsers have more leeway in scaling up, but phones can prefer low- 
> resultion.

how do you suggest they do that then? a different header perhaps. "i  
prefer smaller files to higher quality" could be stated something like:
Accept-Length: 0-5000, 5000-10000;q=0.5, 10001+;q=0.2
then if there are two versions, a low bandwidth one at 2000 bytes and  
a high bandwidth one at 8000 bytes, the smaller one gets sent if it's  
"qs" value isn't too low. What figures the client sends would be  
based on some kind of 'conserve my bandwidth' preference.

(Robert Brewer suggested the same thing as i was writing this!)

> If we leave out the "dpi" tag and allow the value to be a range, it  
> could be specified as:
> 	Accept-Resolution: 70-80;q=3, 50-150;q=2, 150-400;q=1

allowing ranges is something that hadn't occured to me. yes, this  
would allow what you suggest.
q-values should remain in the range 0 to 1 to stay compatible (e.g.  
with things that check for "q=1")

> (note that comma separates the items in an accept header, not  
> semicolon.)

(i know, that's why i used a semicolon!)


> A summer rental house:
> http://www.dancenter.co.uk/house/11508/20071110
> If you click on the "Print page" you get a page using higher- 
> resolution media:
> 1) The red icons to the right on the page, e.g. "grocer's shop",  
> are sent as 150 dpi versions. I fould that 150 dpi was sufficient  
> for pretty output, and 300 dpi was not needed.

those are prime examples of where vector images should be used, where  
the client supports them. same with the DanCenter logo which doesn't  
get a high-res bitmap. the map of denmark could also be vector, or at  
least higher res bitmap.

if you supply those icons as image/pdf and use negotiation, even  
ancient versions of Safari can use them for printing.
if you supply them in SVG too, IE would still get the png version but  
FF and Opera would be upgraded to vector too.
make sre you set source quality on the bitmap versions to 0.25 or  
something, so they don't get picked by things that support other mime  

> (the page lack a lot of text (and might have really bad English) as  
> the site is provided primarly in German and Scandinavian due to the  
> market).

yeah, lots of mistakes :)

- Nicholas.

Received on Thursday, 7 June 2007 19:05:00 UTC

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