

PNG compression case study: Tweetbot for iPad - robin_reala
http://imageoptim.com/tweetbot.html

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al_james
Is it me, or is it slightly worrying that a Twitter client (albeit a very nice
one) needs 978 images amounting to 26MB in the original version? Regardless of
the compressed PNG site, I guess all active images still need to be held in
memory in raw form, taking up valuable device memory.

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pornel
They have completely customized UI, so that's lots of images for button
frames, normal/active icons, spinners, etc. Although some of them could be
created programmatically, I suppose having separate files is much easier for
designers.

Number of images is doubled, because they are regular and Retina versions.

And they don't have to be all in memory. You can reference image by name and
let iOS read it lazily and flush from memory when necessary.

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daemin
I'd be interested to see how (if at all) these optimisations in file size
impact the battery life and performance. Alpha blending isn't free (though
neither is overdraw), and using more CPU than 'disk' could use more power.

Though the differences could be lost in the noise.

Has anyone done these sorts of trials?

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igul222
As I understand it, this is cheating— they used lossy compression on the PNGs
to achieve the size reduction.

