Wednesday, February 20, 2008

X35: Breaking Ice - multispectral

Spring is here finally, but still we have cold nights. When I made use of the fine weather today and that great sun, I found quite some ice in the pond in the Freudenberg park opposite my house ("Hermannshof").

A Baader 2" UV/IR Cut Filter was used for the visible light shots, a Baader 2" U-filter for the UV shots and a B+W 092 IR filter for the IR shots together with a freshly calibrated X35 lens and a unmodified Nikon D70.

The impulsive idea now was, to find out, how differently visible light, ultraviolet and infrared would show the same scene.

[as usual, a click on an image opens up a larger view]

Here now first the visual light shot:

then the shot using the UV filter to get purely reflected UV:

and finally the shot using an IR filter which only allows infrared light to pass:

So what have we here now? Using the above three images, the following image was generated through a mapping of the ultraviolet shot to the blue channel (UV->B), the visual shot to the green channel (VIS->G) and the infrared shot to the red channel (IR->R) of the resulting image. This method is called "multispectral imaging" and is used in 
quite a few scientific fields.

Isn't it interesting, how IR contrary to the visual and especially ultraviolet shot penetrates
the ice surface and makes that leaf so clearly visible? UV however bounces back right from the ice surface, so "illuminates" 
the ice nicely.

So I hope you did enjoy this new method!

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site