Discussion:
unknown
1970-01-01 00:00:00 UTC
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The variations in size you seem to refer to are the Mip/Rip-maps, those =
are targeted for 3D applications.
They basically contain scaled down versions of the main image, in the ca=
se of mip-maps scaled down by a factor of 2 until a size of 1x1 pixels i=
s reached.
If those resolutions can be pushed to the
player individually, then that solves the "realtime" conundrum.
The problem is that none of the lossless compression modes are designed =
for playback (too slow), while the (new) compression mode that is fast e=
nough is lossy.
Machines that need to see it realtime, but can only support it at
half-res, get it that way. Machines (Probably with fast raids and
good graphics cards) that can support playing it back at full-res, can=
do so. I do NOT know that this is actually the case, so it would be
good to hear from a developer who knows.
I'd probably prefer JPEG2000 for that kind of application. Especially si=
nce in JPEG2000 decoding is progressive. Consecutive higher quality "res=
olutions" are built using the (already loaded) lower res image data. Thi=
s allows you to change the quality during playback to adapt to the curre=
nt i/o situation (in theory, I have to admit I haven't tested that yet).=


OpenEXR would require you to load a different set of data from the same =
file to access the higher resolution, discarding the lower res you might=
've loaded previously.
The format can support Scanline Images AND Tile-based images. And it
supports a function to adapt compatibility in case the player doesn't
support one or the other.
Almost. The library doesn't adapt, the player chooses which interface it=
uses to read the images.
The scanline interface can read all types, but only as scanlines.
The tiled interface can only load tiles, but has access to the data as t=
iles as well.
This way, you don't have to load an entire
image just to see a specific region at full resolution.
Again, JPEG 2000 does that as well.

The only issue with JPEG 2000 is the slow decompression and no HDR capab=
ilities.
</QUOTE>
Not that I'm advocatng JPEG 2000 for all cases. I love EXR for how it wo=
rks and what it does, it is a great image format, but not (yet) for what=
you've mentioned above.

Feel free to correct me and flame me off the list now ;)

Cheers
Mike

-- =

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