[Insight-users] Question on MHD format

[Luis Ibanez]

Hi Tim,

An easier way of saving disk space is by compressing
your images.

The MetaImage formal let you gzip your raw files.

What you will have to do is to edit the .mhd files
and update the name of the .raw file in order to
include the additional extension  .raw.gz (or any
other name that you decide to give to the compressed
file).

This compression works quite well for labeled images
since it is based on Run Length Encoding. It doesn't
work quite well on noisy images though....

Note that gzip compression is lossless, so you shouldn't
have any concerns about degradation of the image data
due to the compression.

Please give it a try to compress the raw files (and
modify their name accordingly in the .mhd files) and
let us know if you find any problems.



     Thanks



        Luis




=======================
Tim Soper wrote:
> Hi,
>    I intersted in finding a way to reduce the space
> taken up on my hard drive by a number of raw data
> files roughly 512^3 in size. I find that I am making
> several images that are both clipped versions of the
> original large image as well as creating segmented
> images of these original images for different
> applications.
>    I would like to keep these large images, but I am
> wondering if there is a way to specify a desired
> region of an image through some sort of MetaImage
> header tag. For example, if I wanted just a clipped
> portion of my original image, say 256^3 in size, can I
> simply make a new header file that specifies that
> sub-region of the original image, but referencing the
> same large ElementDataFile? This would preclude
> creation of multiple data files with redundant data.
>    Also, It would be convenient if rather than
> creating new images of segmented regions of my
> original image, I could add another raw data file
> reference to the header that contained an image mask
> of the segmented regions rather than rewriting the
> same image data again. I have looked through the MHD
> file formats and there doesn't appear to be any tags
> that suit this function.
> Please let me know if this is possible.
> 
> Tim
> 
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