Healthy crop and crop affected by disease reflect sun light differently. By using spectral imaging it is now possible to detect very small changes in the physiology of the plant. Spectral imaging is the detection of light reflected by the crop with the use of specialised sensors. It is measured in spectral bands. The higher the number of bands the higher the accuracy, flexibility, and information content.
Hyperspectral cameras currently available have 40+ spectral bands, which allow us to make 40 measurements of spectrum versus the 5–7 bands supported by multispectral cameras.
Currently satellites and drone fitted cameras are using multispectral imaging technology. Multispectral technology can offer a good overview of crop such as overall growth and NDVI (Normalized Difference Vegetation Index), but fails to tackle more complex problems such as weeds, pests, diseases and PK deficiency.
Therefore, spectral imaging is widely used in agriculture and precision farming.