I watched the two essential videos that Jeffrey Warren made about post processing near-infrared a...
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April 27, 2012 16:53
| over 7 years ago
I watched the two essential videos that Jeffrey Warren made about post processing near-infrared and visible images to highlight patterns in vegetation and tried to recreate the magic. The first video is about rectifying two images in Photoshop: http://youtu.be/pv6xB0y-rX4. I used this technique to align a NIR image taken with a PLOTS modified Canon A495 camera on top of a regular image of the same scene. The scene is some Trout Lilies in the woods. The second video is about using GIMP to display combinations of the NIR and visible color data to show enhanced patterns of vegetation health and productivity: http://youtu.be/-nNnWEHNO_w. Below are examples of four different ways to highlight patterns of photosynthetically active plant biomass using images from the PLOTS visible/IR camera tool.
It should be possible to do all of this image work with one or the other of the two programs Jeff uses in the videos, but I haven’t figured out how, so I used Photoshop for the rectifying and GIMP for the analysis just as he does (the obstacle with the analysis is that I can’t figure out how to do division in Photoshop).
I did one important thing different from the second video. In calculating NDVI, Jeff added or subtracted the value of visible light from the value of NIR light. Instead of using all visible light (sum of the red, blue, and green channels), I used only visible red light to more closely mimic the way NDVI is calculated from satellite data.