Forums

what is hyperspectral image?

Started by gino July 19, 2004
Dear folks,

I have heard of a lot buzz about "hyperspectral" image... I did some
googling and did find some researches on this, but I am still not able to
figure out what's it and what's the use of it...

Anybody gives me some pointers?

Thanks a lot,

-Gino


gino wrote:
> Dear folks, > > I have heard of a lot buzz about "hyperspectral" image... I did some > googling and did find some researches on this, but I am still not able to > figure out what's it and what's the use of it... > > Anybody gives me some pointers? > > Thanks a lot, > > -Gino > >
I have a little experience from grad school. Sorry I don't have any links to share, but perhaps I can shed some light on this (white light, hopefully). 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. Cheers, Mark
"Mark Borgerding" <mark@borgerding.net> wrote in message
news:JwZKc.223763$DG4.135332@fe2.columbus.rr.com...
> gino wrote: > > Dear folks, > > > > I have heard of a lot buzz about "hyperspectral" image... I did some > > googling and did find some researches on this, but I am still not able
to
> > figure out what's it and what's the use of it... > > > > Anybody gives me some pointers? > > > > Thanks a lot, > > > > -Gino > > > > > > I have a little experience from grad school. Sorry I don't have any > links to share, but perhaps I can shed some light on this (white light, > hopefully). > > > 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. > > > > Cheers, > Mark
Hi Mark, 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? Thanks a lot, -Gino
IEEE Signal Processing Magazine had a special issue on this
in January 2002.

I recommend checking it out. 

Here is the Xplore URL for the magazine                       
http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=79

In article <cdh97d$g71$1@news.Stanford.EDU>, gino <mizhael@yahoo.com> wrote:
>Dear folks, > >I have heard of a lot buzz about "hyperspectral" image... I did some >googling and did find some researches on this, but I am still not able to >figure out what's it and what's the use of it... > >Anybody gives me some pointers? > >Thanks a lot, > >-Gino > >
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
gino wrote:
> 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?
You might as well ask, "what's the use of a Vernier caliper?" After all, a human can't really tell the difference between 10 mm and 10.01 mm.
"gino" <mizhael@yahoo.com> wrote in message news:<cdh97d$g71$1@news.Stanford.EDU>...
> Dear folks, > > I have heard of a lot buzz about "hyperspectral" image... I did some > googling and did find some researches on this, but I am still not able to > figure out what's it and what's the use of it... > > Anybody gives me some pointers? > > Thanks a lot, > > -Gino
These are the comon definitions: monochromatic, panchromatic, B&W: one band color, false color: 3 bands multispectral: more than 3 bands hyperspectral: 100's of bands ultraspectral: 1000's of bands What's the use of it? Google "spectral analysis"...
Hyperspectral images are used mainly in remote sensing and Medical
imaging applications where a large number of spectral signatures are
needed to capture details in an image.
In many cases, the number of bands actually present exceed the number
of needed bands, so dimensionality reduction is also usually performed
on the hyperspectral image by using simple methods like Principal
component analysis (PCA).
-ARUN
On 2004-07-19 21:59:41 +0200, "gino" <mizhael@yahoo.com> said:

> Dear folks, > > I have heard of a lot buzz about "hyperspectral" image... I did some > googling and did find some researches on this, but I am still not able to > figure out what's it and what's the use of it... > > Anybody gives me some pointers? > > Thanks a lot, > > -Gino
http://www.google.com/search?q=hyperspectral+image+star+trek ;-) -- Stephan M. Bernsee http://www.dspdimension.com
Just imagine a simple photo of some scene, but the photo taking on 
different spectra. That is the camera for example (or the antenna ) 
photographs only specific bands; think of bandpass filters attached to 
the camera. In the visual spectrum: You take photos in different colors. 
 From each spectra you can aquire new informations, actually those 
images look quite different for some spectra. Comparing infrared images 
with "normal images" you can spot "hot" or "cold" zones on the site you 
inspect, so you can say if there is a tunnel or something hollow under 
the surface for example.

Envisat takes multispectral images of the earth. AISA (Airborne Imaging 
Spectrometer) is another example of a device taking multispectral 
images. I guess by hyperspectral images they mean multispectral images 
across a broader spectrum. The Landsat Satellites are early examples of 
multispectral imaging devices, and were used as spy satellites to obtain 
intelligence on the former USSR. The early Landsat Satellites used 
"only" 4 bands if i don't make any mistake. The new devices are capable 
of a much greater range. The aisa is capable for more than 32 images for 
example.
Envisat is one of the most modern type of multispectral imaging devices.



Greetings

P. Chatzichrisafis




Ed Meinel wrote:
> "gino" <mizhael@yahoo.com> wrote in message news:<cdh97d$g71$1@news.Stanford.EDU>... > >>Dear folks, >> >>I have heard of a lot buzz about "hyperspectral" image... I did some >>googling and did find some researches on this, but I am still not able to >>figure out what's it and what's the use of it... >> >>Anybody gives me some pointers? >> >>Thanks a lot, >> >>-Gino > > > These are the comon definitions: > > monochromatic, panchromatic, B&W: one band > color, false color: 3 bands > multispectral: more than 3 bands > hyperspectral: 100's of bands > ultraspectral: 1000's of bands > > What's the use of it? Google "spectral analysis"...