[Bookreader] gnubook/Read-activity update

Michael Ang mang at archive.org
Fri Feb 20 14:57:36 EST 2009

Sayamindu Dasgupta wrote:
> Hi Raj,
> On Wed, Feb 18, 2009 at 10:52 AM, raj kumar <rkumar at archive.org> wrote:
>> The flippy.zip, which is used by the old flipbook, is 3.8 MB.
>> But the jp2.zip, which is used by the new flipbook (GnuBook), is 43.9 MB
>> -raj
> What is the major difference between/advantage over the two formats ?
> Thanks,
> Sayamindu
The JP2s allow access to the full resolution of the source images (this 
isn't true of the JPGs in the flippy.zip).  The JP2 format allows 
efficient retrieval at power of 2 size reductions and we use this 
feature in GnuBook to support zooming in and out.  JP2 also allows 
efficient retrieval of sub-regions of an image which we'd like to use in 
the future to support retrieving large images as a set of tiles (should 
be especially useful in 1-up mode when not all of a page is visible to 
the user).

  - mang

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