02 Aerial Colour Image Analysis

Aerial image analysis was performed using the public domain image analysis software Image-J (NIH) 1. The red/green/blue channels of the images were split and the blue and green channels were subjected to the AND logical operation, the resulting image was then subjected to the logical OR operation with the red channel. The resulting black and white image (Glenorchy BorGandR, below)was threshold into four regions based on the gray level regions indicated from their histogram (see bleow). Three of the threshold regions were then assigned the RGB colours and mixed to generate a false colour image of the open field area  RGB Composite2 forb_grass_cespitose.

Glenorchy blueORgreenANDred image composite

B&w histogram of the BlueORgreenANDred composite image

B&w histogram of the BlueORgreenANDred composite image


Table M1: Image analysis of coloured areal pictures.

(File Name)

Logical operations

Histogram Interpretation

False colour figure

(Glenorchy BorGandR)

(Blue OR Green) AND Red

190 – 255: open ground

120 – 160: tall grasses

90 – 120: cespitose grasses

50 -90: forbs and small shrubs, light foliaged trees.

0 – 50: shrubs and tree with strong shade and shadows

green: open ground and tall grasses

red: forbs, cespitose grasses, (light foliage trees)

blue: large shrubs, dark foliage trees.


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