Subject: Re: 12 bit gray file formats

From: [email-masked] (Dave Ahn)
Date: 20 Jul 1994 21:00:05 GMT

[email-masked] (X-Ray Scanner Corporation) writes:

>I'm looking for file formats capable of storing 12 bit
>grayscale images.  The ideal format would already have some
>tools (commercial or public domain) capable of dealing with it.

>I've already looked at the ACR/NEMA DICOM 3.0 draft (chapter 10,
>Media Storage and File Format). It would be fine, except I can't
>find any PC or Mac tools which read DICOM.

>Any info would be appreciated. 
>Thanks in advance.

We have 12 bit grayscale CT images and ran into the problem of storing
them efficiently (i.e. not convert them to 16 bit and waste 4 bits).  We
couldn't find a solution that was portable enough between multiple
platforms, so we're simply using an in-house file format.  We've
modified some of our graphics programs and apps to automagically
detect this image type.  In order to use the images outside of our
programs, we'd have to store them in 16bit grayscale image or volume
files.  If loss of data
is acceptable to you, you may want to consider cutting out 4 bits
by applying a colormap reduction algorithm that will reduce the 12bits
to 8bits.  This works remarkably well for us with little loss of
significant data and is portable to nearly any platform.

Dave.
>-- 
>----------------------------------------------------------------------
>X-Ray Scanner Corporation                               [email-masked]
--
Dave Ahn                            Internet: [email-masked], [email-masked]
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 "When you were born you cried, and the world rejoiced.  Try to live your life
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From: [email-masked] (Dave Ahn)
Date: 20 Jul 1994 21:00:05 GMT

Dave.