Posted by
Gabriel Landini on
URL: http://imagej.273.s1.nabble.com/Infrared-filter-on-RGB-image-tp5001401p5001415.html
On Monday 14 Jan 2013 18:36:39 you wrote:
> Actually, I have a color image (captured from an ordinary camera) on which I
> want to produce an effect as if during the time of capture, the object was
> exposed to some wavelength.
No you can't achieve that on an image that has already been captured because
you do not know which parts of the image reflect or absorb IR light.
Digital cameras typically have an infrared blocking filter because the sensors
usually respond to the near infrared as well as in the visible spectrum. That
being said, a tiny amount of near infrared light gets in the camera and gets
mixed with the visible light, and this can be captured if you use a visible
light blocking filter like the Hoya R72 or the Wratten 89B (you can get these
filters in photographic equipment shops). But you can't really separate the
NIR light from the rest of the image once it is shot.
Some people remove the IR blocking filter from the camera to have more
sensitivity in the NIR, but this is not something you may want to do with an
expensive camera. With some webcams this can be done very easily.
See for example:
http://www.hoagieshouse.com/IR/Regards
Gabriel
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