ML VISUAL LAB / REMOTE SENSING

Spectral Indices from Band 4 & 8

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NDVI

Experiment controls

Spectral indices

Sample dataset

Index type

Matrix size

Band 4 response (red)1.00×

Band 8 response (NIR)1.00×

Both bands scale100%

SmallerOriginal sizeLarger

Resize both bands while keeping every cell aligned.

Upload Band 4 and Band 8

Both must be grayscale images of the same area, up to 2 MB each.

Band 4 · RedBand 8 · NIR

ACTIVE PIXEL CALCULATIONNDVI = (B8 − B4) / (B8 + B4)

(0.00 - 0.00) / (0.00 + 0.00) = 0.00

B4 0.00B8 0.00NDVI 0.00

Mean0.00

Positive values0%

Very high values0%

Selected pixelx 128 · y 96

Click any pixel to inspect Band 4, Band 8, and the formula result.

NDVI calculation from two band imagesMove Band 4 and Band 8. Their overlap is calculated immediately.

Band 4 · reddrag

Band 8 · NIRdrag

NDVI · overlap

Overlap is calculated pixel by pixel with (B8 − B4) / (B8 + B4)

Understand This Experiment!

Spectral indices always come from combining two or more bands. Here Band 4 and Band 8 are merged with a formula, not just stacked, so the value can be read as vegetation health or water presence.

Core formula

NDVI = (B8 − B4) / (B8 + B4)

Band 4 (red) is absorbed by vegetation while Band 8 (NIR) is strongly reflected, making vegetation contrast clearly.

When to use it

NDVI for vegetation and forests, NDWI for water and wetness, SAVI for open soil areas, GNDVI for young green cover.