![]() In some cases a constant was added to the NDVI values of all the pixels to shift them to a more meaningful range. If a normal color photo is included, the NDVI image was derived from a two-camera system. I have included the original photo, either normal color or Wratten 25A super-red Infragram. In many cases, DIY NDVI values above 0.9 are artifacts where the image is very dark or very bright.īelow are some NDVI images colored with the new colormap. I did not make it a gray so it can be distinguished from low values. Foliage generally does not have NDVI values this high, so this color represents non-plants. Different sites produce slightly different results, but it is obvious that the eight percent of white men with color blindness ( 0.9) are colored magenta. There are lots of web sites which show you what a color photo looks like to a color blind person. Protanopes see this gradient very differently. NDVI values above zero are assigned colors on a gradient from green through yellow to red, so greater photosynthesis is highlighted with hotter colors. NDVI values below zero are assigned a blue color. My standard color map for NDVI images (top), and how it looks to a person with protanopia (bottom). A long time ago, someone suggested that this type of color map was not helpful to people with red/green color blindness like protanopia. You can use any color scheme you want, and I have been using one that turns images into "heat maps" of photosynthetic activity by painting high NDVI values with hotter colors. ![]() If you have a value for every pixel, you can assign different colors to different ranges of NDVI values and make a false color map of how NDVI varies spatially. Or an NDVI value can be determined for every pixel in a photograph of a leaf or of a corn field. ![]() ![]() ![]() A single NDVI value can be determined for an individual leaf or a 200 acre corn field. NDVI is an index (a unit-free number) related to how much photosynthetic activity is occurring. ![]()
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