Getting simultaneous red and near-infrared band data from a single digital camera for plant monitoring applications: Theoretical and practical study

• R and NIR bands can be obtained from a RGB camera after removing the internal NIR filter.
• R and NIR bands are obtained by linear combinations of the raw channels.
• Theory of operation and practical concerns (noise, demosaicing) are investigated.
• Satisfactory NDVI images from agricultural scenes are obtained with Canon 500D and 350D.

Multispectral images, including red and near-infrared bands, have proved efficient for vegetation–soil discrimination and agricultural monitoring in remote-sensing applications. However, they remain little used in ground-based and unmanned aerial vehicle (UAV) imagery, due to a limited availability of adequate 2D imaging devices. A methodology is proposed to obtain simultaneously the near-infrared and red bands from a standard single RGB camera, after having removed the near-infrared blocking filter inside. Its ability to provide satisfactory NDVI (normalised difference vegetation index) computation for vegetation and soil has been assessed through spectral simulations. Application in field conditions with Canon 500 D and Canon 350D cameras has then been considered, taking into account signal–noise and demosaicing concerns. The results obtained have proved the practical usability of this approach, opening new technical possibilities for crop monitoring and agricultural robotics.