Re: [public-respimg] Responsive File-Format

Hi Mohsen,

this topic has been 'discussed' a while ago in the CG Forums and I also wrote about this a while ago [1]. 
While saying that, there are some point which make clear this is a wanted behavior but not the 
ultimate solution for responsive images:

1. File format features
You're saying that WebP and JPEG is able to download image content really progressively
this is not true. Both formats as they're implemented in browsers don't support this kind 
of streaming related to the calculated layout. There are image formats that support this [2], but
WebP and JPEG at its current state don't support this afaik. Both could indeed implement it for
their file format.

2. File format support
But even if WebP or JPEG would support this, this needs to be implemented widely across browsers.
This is even more unlikely in the short term, and as it is not polyfillable you will get one major problem:
As you define the biggest size image as default, every device not supporting the new format will get 
the whole big image. This would be the opposite of what we want to achieve by responsive images.

3. Performance
Also by specifying the largest size by default you will get a problem with browsers lookahead preparers.
As of the time they're running no CSS, and therefore no layout, is composited the browser will download 
the full resolution. One might be able to avoid this by going the other way around 'smallest first' but I am 
not the one who is able to say that for sure.

I hope this helps you why current solutions look a bit different but your thoughts are not wrong.

[1] http://helloanselm.com/2012/a-chance-for-webp/
[2] http://en.wikipedia.org/wiki/MrSID

Cheers,
Anselm | @helloanselm

On 27.06.2013, at 19:47, Mohsen Nabiloo Azimi <msnazi@gmail.com> wrote:

> Pardon my lack of research if I'm bringing up something that is already discussed. I've looked around but didn't see anything like what I have in mind in archives.
> 
> This is how I see responsive images problem in current web:
> 
> We want one image in markup but that image should work great in large
> screens, small screens and screens with high DPI. At the same time, we
> might change image size and even image crop dependent on viewport width,
> orientation or media type.
> 
> I think browsers can take care of this problem with progressive image
> loading technologies that are available for WebP and JPEG. How? By
> following this simple rule:
> 
> Load enough pixels to satisfy current view of image in current screen.
> Web developer would put a <img tag with source to the largest image
> they have. Browser will determine how much of that image should be
> downloaded based on how that image is presented in web page.
> 
> For example, if an image is 2000 by 2000 pixels, but it's resized to 200
> by 200 pixels, browser would not download whole image and scale it down.
> It will actually just download enough pixels to cover the area that
> image is covering. And likewise, if image is sized to 300 by 300 pixels
> browser would download that much "pixels".
> 
> Have anybody thought about this before?
> 
> Thanks,
> Mohsen