• Ultraviolet Photography

Cucurbita cf. pepo [Ornamental Gourd]

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#1 Andrea B.

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Posted 16 February 2014 - 17:23

Blum, A.G. (2013) Cucurbita cf. pepo L. (Cucurbitaceae) Ornamental Gourd. Gourd photographed in ultraviolet, visible and infrared light. Channel stacks. http://www.ultraviol...namental-gourd/

Middletown, New Jersey, USA
12 November 2008
Purchased at grocery store

This pretty orange Gourd made a nice still life subject. In UV the irregular growth flaws and various scrapes from handling are more obvious although some of that still shows up in the IR photo.

1. The American Gourd Society (2014) This is a nonprofit organization dedicated to the education and instruction of those persons who are interested in the culture, uses, history, and/or crafting of gourds.

Equipment [Nikon D200-broadband + Novoflex 35mm f/3.5 Noflexar]

Visible Light [f/11 for 1/180" @ ISO 400 in Sunlight with Baader UVIR-Block Filter]
Click, then click again to see the largest version.
Attached Image: orangeGourdVis121108wf_25394origpnpf.jpg

Ultraviolet Light [f/11 for 4" @ ISO 400 in Sunlight with Baader UV-Pass Filter]
Shooting UV with my old D200-broadband could really bring out the noise. That combined with resizing has induced a few artifacts.
Click, then click again to see the largest version.
Attached Image: orangeGourdUV121108wf_25390origpnpf.jpg

Infrared Light [f/11 for 1/125" @ ISO 400 in Sunlight with B+W 092 IR-Pass Filter]
Click, then click again to see the largest version.
Attached Image: orangeGourd092IR121108wf_25387origpnpf.jpg

The preceding Visible, UV and IR frames were stacked as difference layers in Photoshop. Making a composite like this does not always reveal anything particularly unusual. It's just fun to do. The layers do not match up perfectly, so you can detect a few edge discontinuities in the full-sized version.
Attached Image: orangeGourd121108wf_25394origpnpfDiffStack.jpg

Multispectral Channel Stack [UV->Purple, Visible->GreenBlue, IR->Orange]
Each frame was assigned to a colour channel. Typically this is done via an RGB channel assignment. I sometimes like to use Purple (128,0,255), GreenBlue(0,255,128) and Orange(255,128,0) instead. Again, such a composite may not be particularly meaningful, but the result is pretty.
Attached Image: orangeGourdVis121108wf_25394pnpfUvPIrOViGComp1.jpg

Multispectral Channel Stack
This is the preceding stack with a 45° turn of the colour wheel. The gourd is starting to look like an apple!
Attached Image: orangeGourd121108wf_25394pnpfUvPIrOViG45Comp2.jpg

Colorized Triptych
I put the Visible frame as a Color layer over the UV frame and then the IR frame in order to "colorize" them. The three photos were then combined in this triptych. The forum software's auto-resizing has clobbered the result a bit, but you can still get the general idea. From left to right, the UV, the Visible and the IR frame, respectively.

Attached Image: gourdTriptychResizeLabel.jpg

Andrea G. Blum
Often found hanging out with flowers & bees.

#2 colinbm


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Posted 16 February 2014 - 20:25

You are too good Andrea, a beautiful presentation.