Re: MrSID multiple resolutions - Simone Giannecchini - net.java.dev.imageio-ext.dev

5 messages in net.java.dev.imageio-ext.devRe: MrSID multiple resolutions

From	Sent On	Attachments
Nidel, Mike	Sep 12, 2008 7:43 am
Nidel, Mike	Sep 12, 2008 11:35 am
Simone Giannecchini	Sep 12, 2008 11:41 am
Nidel, Mike	Sep 12, 2008 11:43 am
Simone Giannecchini	Sep 12, 2008 11:48 am

Subject:	Re: MrSID multiple resolutions
From:	Simone Giannecchini (simb...@gmail.com)
Date:	Sep 12, 2008 11:48:15 am
List:	net.java.dev.imageio-ext.dev

I have experience myself "strange" performances with very large MrSid files. By strange I mean unexpected slow read at low and intermediate resolutions as well as very fast read at full res. I guess that:

1> it depends very much on how the file was encoded (well, at least this is tru for jp2 files :-) ) 2> it would be "great" to try and bind directly to the MrSID SDK, bypassing GDAL (sacrilegy, I am not criticizing GDAL :-) ). I t would not be that difficult.

Ciao, Simone.

On Fri, Sep 12, 2008 at 8:43 PM, Nidel, Mike <mike...@lmco.com> wrote:

Excellent. So the subsampling values that make sense for MrSID are 1, 2, 4, 8, 16 etc. right?

I have it working so far, but it doesn't seem to be very fast. Ah well.

Good luck with your crazy deadlines!

------------------------------ *From:* Simone Giannecchini [mailto:simb...@gmail.com] *Sent:* Friday, September 12, 2008 2:42 PM *To:* de...@imageio-ext.dev.java.net *Subject:* Re: MrSID multiple resolutions

Ciao Mike, I am running literally, so do not rely too much on me, but yeah, the last time I have checked getNumOverviews should tell yo how may resolutions level you have in the file. Note that the scale factor is always 2 (wavelet compression).

Ciao, Simone.

On Fri, Sep 12, 2008 at 8:35 PM, Nidel, Mike <mike...@lmco.com> wrote:

I've tried using the getNumOverviews(), and this seems to be correct... am I on the right track?

-----Original Message----- From: Nidel, Mike Sent: Friday, September 12, 2008 10:43 AM To: de...@imageio-ext.dev.java.net Subject: MrSID multiple resolutions

I've got some code working to decode MrSID multiple resolutions from within a single file. What I don't know is what field in the metadata tells the user how many resolution levels are available. Where can I find that? Is it COMPRESSION_NLEV?

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