Transform ECW to MrSID

Llu?s Tartera

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Feb 23, 2005, 5:45:21 AM2/23/05

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Hello to everybody,

I have a question about format transformation, I like
to convert some images in one format to another.

I have some ECW files, and i want to convert this files into
another format, the MrSID format, because I think is better ...

ButI don't know how can I do this action.

Could somebody help me, please?

Thanks in advance.

Lluís

Frank Looper

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Feb 23, 2005, 2:00:59 PM2/23/05

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> I have some ECW files, and i want to convert this files into
> another format, the MrSID format, because I think is better ...
>

Before you buy MrSid software, you might consider changing them into 256
color GeoTiff files with LZW compression. Those shrink up wonderfully and
the software for that is everywhere.

Frank

Grail

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Feb 23, 2005, 5:37:53 PM2/23/05

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I don't know of any "direct" way to do it. You basically have to decompress
the MrSid to a geoTiff, and then recompress it w/ the LizardTech
application.

Out of curiosity, why do you feel the MrSid format is better? Anecdotally,
we (where I work) tested it in a few different places and ECW performed
faster the MrSid in both our CAD and GIS applications and appears to give a
sharper image... The ECW file sizes were slightly larger though, but not
significantly. Additionally, ERMapper (makers of ECW) have free downloads
for a compressor (500mb or less images) and viewer. I'm not a fan of
LizardTech's browser plug-in. I liked their older GeoViewer better:-)
--

---------------
James Burn BSc, GIS(pg), AScT

"Llu?s Tartera" <lluis....@gmail.com> wrote in message
news:927f03e7.05022...@posting.google.com...

Stichting ST

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Feb 24, 2005, 5:17:16 AM2/24/05

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On Wed, 23 Feb 2005 17:37:53 -0500, "Grail" <gr...@cogeco.ca> wrote:

>I don't know of any "direct" way to do it. You basically have to decompress
>the MrSid to a geoTiff, and then recompress it w/ the LizardTech
>application.
>
>Out of curiosity, why do you feel the MrSid format is better? Anecdotally,
>we (where I work) tested it in a few different places and ECW performed
>faster the MrSid in both our CAD and GIS applications and appears to give a
>sharper image... The ECW file sizes were slightly larger though, but not
>significantly. Additionally, ERMapper (makers of ECW) have free downloads
>for a compressor (500mb or less images) and viewer. I'm not a fan of
>LizardTech's browser plug-in. I liked their older GeoViewer better:-)

I can confirm some observations.
Both methods use basically the same technic (wavelet) and both give the same
kind of artifacts which high compressionrates.
When working with maps ecw is superior to MrSid, we have observed. Images are
sharper because lines are kept much better together in ecw.
Try for once a picture with text only. Then the difference is very clear
between the two.
When working with aireal colourphotographs differences are small between the
two.
And about processing power needed for reading/displaying: ecw is much faster
on an old slow notebook.
Comparision for Windows CE could not be made (no Mr.Sid) but ecw works with
this free available library: Trimble ECW Decompression SDK for Windows CE and
Pocket PC
http://www.ermapper.com/downloads/download_view.aspx?PRODUCT_VERSION_ID=202

Piet

Costas Margetousakis

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Apr 4, 2005, 9:52:59 PM4/4/05

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On 23 Feb 2005 02:45:21 -0800, lluis....@gmail.com (Llu?s Tartera)
wrote:

- Use Ermapper and save your .ecw to .tiff
- Use Erdas Imagine (import utility) and import .tiff to .img
- " " and export .img to .sid

>Thanks in advance.
>
>Llu?s