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Working with Public Laboratory, analyzing images

posted Feb 23, 2011, 1:30 AM by Cesar Harada   [ updated Feb 23, 2011, 1:38 AM ]

One of the things that Protei may be able to do is to transport physical oceanographic equipment such as sonar. 
I regularly collaborate with the Grassroots mapping group that is now becoming officially formed as the Public Laboratory
In this video tutorial co-edited with Adam Griffith of the University of Western Caroina, we demonstrate how to extract a specific color from a UV picture and quantify how much area of wetland there is on this image. 

>> Question : How can you extract the % of wetland from an UV aerial picture using photoshop?

_ Instructions :
1. isolate the part that you are interested in using the menu/ image/ adjustment/ replace color. There you want to have a quite fuzzy selection and darken the desired part. 

2. after isolating the part you are interested in -black area- apply menu/ image/ adjustment/ threshold

3. use magic wand /untick "contiguous" pixel to select all the black pixels available. Open menu/ window/ histogram/ expanded view. Here you will see how many black pixels are selected. Now you know how many black pixels there is on this image - corresponding the area of wetland from the original UV picture. You can convert the number of pixels into a % (proportions of wetland) or in surface area for quantifying. It is possible to optimize this workflow by creating a script or recording the chain of actions.

We may be able to use such simple technique with Protei when transporting scientific observation equipment.