Public Lab is an open community which collaboratively develops accessible, open source, Do-It-Yourself technologies for investigating local environmental health and justice issues.
<img src="https://publiclab.org/sites/default/files/imagecache/default/barataria-nrg.jpg" />
If you have [near-infrared imagery](/tool/near-infrared-camera) you can composite that imagery with the visible-light imagery to see how healthy the vegetation is.
* [NDVI and NRG compositing](/wiki/ndvi)
* [Video: Creating infrared composites of aerial wetlands imagery](https://www.youtube.com/watch?feature=player_embedded&v=pv6xB0y-rX4) - Learn to combine infrared and visible-light photographs (taken from balloon photography) to produce an "NRG" composite, where reddish color indicates photosynthesis.
* [Video: Creating false-color NDVI with aerial wetlands imagery](https://www.youtube.com/watch?v=-nNnWEHNO_w) - Learn to use the open-source GIMP application to create a Normalized Differential Vegetation Index image from infrared and visible-light aerial photographs. Also explore false-color techniques for presenting the data.
<img src="https://publiclab.org/sites/default/files/imagecache/default/IMG_7316-enhanced.jpg" />
Stretch the contrast and saturation of your images to see more detail, especially underwater. Read more here:
_Nathan Craig writes:_ Decorrelation stretching may be a method to consider. Various flavors of the transformation are easily run using the DStretch Plugin for Image J. Several that seemed to represent variability relevant to the case study are included. I use DStretch to help bring out detail in rock art scenes that are highly eroded. However, the method has utility outside of rock art studies. It may be an additional approach to consider when trying to identify pollution or other contaminants.
Here is information on DStretch
Here is a paper that describes the transformation
<a href="https://www.flickr.com/photos/publiclaboratory/6287342098/" title="Fwd: contrast enhancement to view underwater features in aerial photos by publiclaboratory, on Flickr"><img src="http://farm7.static.flickr.com/6042/6287342098_b4158df2b3.jpg" width="374" height="500" alt="Fwd: contrast enhancement to view underwater features in aerial photos"></a>
[Browse more of these](https://www.flickr.com/photos/publiclaboratory/sets/72157627992773600/detail/)
Using the ratios of Red, Green, and Blue (and possibly Near-infrared), spectral classification attempts to categorize regions of an image by land type.
###Read more on the [classification page »](/wiki/classification)###
<a href="https://www.flickr.com/photos/worldworldworld/4918161225/" title="how much oil hit the coast ? by cesarharada.com, on Flickr"><img src="https://farm5.staticflickr.com/4074/4918161225_ac11e4ffa4.jpg" width="500" height="156" alt="how much oil hit the coast ?"></a>
<img width="500px" src="https://publiclab.org/sites/default/files/USCB_GeniePro_Classification.jpg" />
### Image Analysis