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Comment by gurgeous | Hacker News Reader

Ooh, cool! We're using JPGs, though. At quality 75:

   67K  flT7c.jpg
  558K  flT7c.png

Once those JPGs make it across the network and arrive on the device, we're stuck with plain old CGImages, right?

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Yeah. When you load a JPEG image, it gets decoded to a 32bpp image in memory on the device. PVRTC images, on the other hand, stay the same size (2bpp or 4bpp) when loaded into memory. Plus they don't need to be decoded.

So this 512x512 image would take 64k of RAM using 2bpp pvrtc, 128k using 4bpp pvrtc, and a whopping 1MB using JPEG or PNG.

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