On Tue, 2012-03-20 at 11:44 +0000, Derek Mortimer wrote:

> Looking at the image you referred to, Firefox tells me that it is
> 7,360px × 4,912px (scaled to 864px × 577px).  If what I have been told
> is correct, that 1 pixel = 1 byte ( or thereabouts), that is a 36mb
> file, which to my mind is enormous.

That's correct for an 8-bit GIF image but not much else. For JPEG at
8-bit per channel it's 24 bits, i.e. 3 bytes, per pixel. For PNG with
alpha channel, 4 bytes per channel, but a camera raw file is likely to
use 16 bits per channel per pixel in RGB (even though not bits are used
for most cameras) giving 6 bytes per pixel, and about 215 MBytes of

The compressed JPEG file should be quite a bit smaller, of course.

I routinely deal with images that are over a gigabyte.


Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org www.advogato.org

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