Sunday, March 9, 2008

Primula III ... Multispectral Imaging

So, that Primula again. How boring? Guess not ... since today it will be more than "just" that effect of stimulated IR flourescence, it will be about Multispectral Imaging also. And that means combining shots done in different wavelengths of light (not necessarily visible light) into just one image. So this is how that well known flower looks like in visible light:

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

Under UV light, using a combination of Xenon and a 365nm Nichia UV LED flash/lamp, the scene now looks like this. Not much UV reflection actually, this is why it looks a bit dull. If you look more carefully, you might notice how UV light enhances even the smallest details and especially shows damages to the sensitives flower petals, like nicks and bruises (a reason why UV photography is used in forensics with great success, since even older marks which might not yet or no longer be visible, would still show under UV light).

Using the same UV light, but an UV stopping filter in front of the X35 lens, in this case the 2" Baader UV/IR Cut filter, the scene now changes since it is about UV stimulated flourescence what we see. The pollen lights up greenish/blueish and that deep red lights up from the green leaves actually is red IR flourescence (stimulated by UV).

Changing back to visible light, but using a deep red IR filter, yields the following result (not that spectacular, since there is not much IR response):

If we now map three of the images above into one resulting image via UV --> B, VIS --> G, IR --> R channels and combine these into one image, we get:

Which now shows three different wavebands combined in just one image.

So I hope you enjoyed that "multispectral" Primula flower!

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

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