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Re: Compressive images test

From: Kornel Lesiński <kornel@geekhood.net>
Date: Fri, 13 Sep 2013 00:26:19 +0100
To: public-respimg@w3.org
Message-ID: <op.w3bnd5jbte2ec8@aimac.local>
On Fri, 13 Sep 2013 00:17:38 +0100, Jason Grigsby <jason@cloudfour.com>  

> Compressive images[1][2]. I love the idea and fear it at the same time.
> Love it because it would be oh so easy and awesome. Fear it because even  
> if
> the file size is smaller, I worry that a memory constrained UA would have
> trouble decompressing images that contain four times the pixels.

Luckily JPEG has unique ability to cheaply decompress at fraction of its  
size. iOS already uses that to downsample images that are too big for it  
to load into memory (imposes limit of 2 megapixels per image).

JPEG is made out of 8x8 blocks, but the decoder can decompress JPEG to any  
block size it wants, so it can write 4x4 or even 1x1 blocks instead of 8x8  
pixel ones, so it never has to create a large image (but of course current  
browsers are not as conservative with memory and will waste it).

regards, Kornel
Received on Thursday, 12 September 2013 23:26:49 UTC

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