[OSGeo-Discuss] 'lossless' JPEG2000

[Michael P. Gerlek]

I've not read the whole Wikipedia article, but the statement "images
have to be transformed from the RGB color space to another color space"
is indeed incorrect.  Images that are 3-banded MAY be encoded with the
YCC transform, but this is not required; images with some other number
of bands do NOT undergo a color transform step.


If you're using ERMapper (ECW) files now, you're already deep into the
world of lossy transforms.  Imagine files (.img) are lossless, I
believe, so you're safe there.


My offer to encode a few GB of sample data for you still holds :-)

-mpg 

 



________________________________

	From: discuss-bounces at lists.osgeo.org
[mailto:discuss-bounces at lists.osgeo.org] On Behalf Of
Bruce.Bannerman at dpi.vic.gov.au
	Sent: Tuesday, February 26, 2008 2:12 PM
	To: OSGeo Discussions
	Subject: RE: [OSGeo-Discuss] 'lossless' JPEG2000
	
	

	IMO: 
	
	
	Michael, 
	
	Again, I don't pretend to be an expert on JPEG2000. However, I'd
like to know more about the format for future reference. 
	
	Does the wiki article at the following URL represent a good
overview of the format? 
	
	http://en.wikipedia.org/wiki/JPEG_2000 
	
	
	
	If it is accurate, there is a section that leads me to conclude
that the format is not suitable for a lot of remotely sensed spatial
imagery: 
	
	
	<snip> "Color components transformation 

	Initially, images have to be transformed from the RGB color
space <http://en.wikipedia.org/wiki/Color_space>  to another color
space, leading to three components that are handled separately. There
are two possible choices:..." </snip> 
	
	
	If this *is* the case, then I wouldn't be able to use the format
to store multi and hyper spectral imagery (ignoring other JP2 issues). 
	
	
	As to what format are we using currently:    The source format
that the data came in with appropriate Geophysics, ERMapper and in some
cases Erdas Imagine conversions. 
	
	What are we using in the future:   To be determined, probably a
database oriented solution. 
	
	
	As to data corruption:   Many image processing algorithims and
processes result in data loss. The aim for most people is to understand
what is acceptable and to minimise the corruption of their data. 
	
	In our situation, some of the imagery may result from many
millions of dollars spent in capture and processing. Much of it is
irreplacable. All of it must be protected for future use. 
	
	
	Bruce
	
	
	
	
	

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