Re: what is hyperspectral image?

From: Martin Brown (|||newspam|||_at_nezumi.demon.co.uk)
Date: 07/20/04 

Date: Tue, 20 Jul 2004 11:28:55 +0100

In message <cdhsdb$8c6$1@news.Stanford.EDU>, gino <mizhael@yahoo.com>
writes
>
>"Mark Borgerding" <mark@borgerding.net> wrote in message
>news:JwZKc.223763$DG4.135332@fe2.columbus.rr.com...

>> The color of light is detected by the human eye at just three
>> frequencies in a very small portion of the infinite spectrum. Any
>> different shades you perceive are just weighted combinations of the
>> three primary colors. (Incidentally, the names applied to these colors
>> seems to vary by profession.)
>>
>> Camera equipment is not limited by the shortcomings of rods and cones.
>> It can "see" much narrower frequency bands than the human eye. It can
>> extend below and above the human limits of red and violet. Specialized
>> equipment may well "see" over a hundred colors.
>>
>> I recall using hyperspectral images with ~107 bands,16 bits per band,
>> per pixel.

>Thank you very much for your help. Now I have better idea about this... but
>what's the use of such sophisitcation? What's the use of some color that
>cannot be observed by human eye? I also want to ask how new is this term?

Our eyes are limited to the visual band. Choose other wavelengths and
you can for example see unhealthy vegetation before disease really takes
hold, prospect for minerals, see thermal hot spots or find people lost
in fog.

It has been around for ages. The hype is in giving it a name.

It has always been routine to observe astronomical objects in as many
wavebands as possible ranging from 1m length radio waves to hard X-rays.
You hope to glean additional information from each waveband used.

The limitation was having the sensor technology and instrumentation to
get decent quality images. Now we do have imaging detectors for most
wavebands hyper spectral imaging has come of age.

Regards, 

-- 
Martin Brown