[Gdal-dev] MrSID Driver v. 4.0.x overviews
bfraser at geoanalytic.com
Wed Aug 4 12:13:10 EDT 2004
Have you made any progress with the MrSid driver reading RGB data?
To get it to compile, I had to make a small change in mrsiddataset.cpp.
was changed to
Also, nmake.opt, lines 110,111:
MRSID_LIB = /LIBPATH:$(MRSID_DIR)\lib\Release_md \
lti_dsdk.lib advapi32.lib user32.lib
were changed to:
MRSID_LIB = $(MRSID_DIR)\lib\Release_md\lti_dsdk_dll.lib \
----- Original Message -----
From: "Andrey Kiselev" <dron at ak4719.spb.edu>
To: <gdal-dev at xserve.flids.com>
Sent: Wednesday, July 21, 2004 11:32 AM
Subject: Re: [Gdal-dev] MrSID Driver v. 4.0.x overviews
> Hi, Michael,
> Thank you for your comments!
> On Wed, Jul 21, 2004 at 09:50:13AM -0700, Michael P. Gerlek wrote:
> > > Maybe one reason is that to read an RGB image I believe each tile is
> > > decompressed 3 time, one time per component... About the same
> > > problem with the GeoTIFF driver, Frank said that we can optimize
> > > this by reading interleaved data in one pass by using the
> > > GDALDataset::RasterIO() ; maybe we can also implement this for the
> > > MrSID Driver ? Maybe we can also try to remove the memcpy in the
> > > IReadBlock function and read directly data into the GDAL buffer.
> > > (Maybe there are some optimization to do using the MrSID API
> > > differently ?)
> > Yes, one scene read will decode all three bands at once (they are
> > encoded together, due to the RGB->YIQ color transform).
> > I think you can easily use the GDAL buffer instead of having to
> > memcpy; the LTISceneBuffer is designed specifically for this kind of
> > thing. What is the format/organization of the GDAL buffer?
> I'm not sure that we can use LTISceneBuffer directly... The buffer
> is sized to hold data for the single band, so if we read 8-bit image
> using X*Y blocks it will be X*Y bytes long. But it is not enough for
> LTISceneBuffer, because it wants to decode all image bands, so the buffer
> size should be X*Y*nBands bytes. That's why I'm using separate buffer
> created by the LTISceneBuffer and copy the date into GDAL buffer
> Andrey V. Kiselev
> Home phone: +7 812 5274898 ICQ# 26871517
> Gdal-dev mailing list
> Gdal-dev at xserve.flids.com
More information about the Gdal-dev