Research Article
Utilization of Machine Vision to Monitor the Dynamic Responses of Rice Leaf Morphology and Colour to Nitrogen, Phosphorus, and Potassium Deficiencies
Table 1
Indices calculated from different leaf characteristics.
| | Category | Index | Formula |
| | Morphological indices | Leaf width (LW) | | | Leaf length (LL) | | Leaf area (LA or CLA) | | Leaf perimeter (LP) | | Colour indices | Red (R or CR) | | Green (G or CG) | | Normalized red index (NRI) | NRI = R/(R + G + B) | | Normalized green index (NGI) | NGI = G/(R + G + B) | | Dark green colour index (DGCI) | DGCI = {(hue − 60)/60 + (1 − saturation) + (1 − brightness)}/3 | | Excess green vegetation index (ExG) | ExG = 2NGI − NRI − NBI | | Excess green minus excess red (ExGR) | ExGR = ExG − ExR | | Green-red vegetation index (GRVI) | GRVI = (G − R)/(G + R) | | Kawashima index (IKAW) | IKAW = (R − B)/(R + B) | | Principal component analysis index (IPCA) | IPCA = 0.994|R − B| + 0.961|G − B| + 0.914|G − R| |
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CLA, CR, and CG represent the LA, R, and G of the chlorotic part, respectively.
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