5.15.4. True Colour Composite (TCC) images

In a multispectral image, when the three primary colour bands are combined in a different way, the resultant image is called a true colour composite image (Figure 5.35, left image).

True Colour Composite (TCC) images are a type of remote sensing image that combines three specific spectral bands—red, green, and blue—into a single image. These bands correspond to how we perceive colors in the natural world. For example, in the LANDSAT TM images, the red band is labeled as band 3, the green band as band 2, and the blue band as band 1. When these bands are combined, the resulting image resembles what a human observer would see, making TCC images particularly useful for visual analysis.

Think of creating a TCC image like mixing paint. If you have red, green, and blue paint, blending them in the right proportions will give you a color that can represent objects in the real world—like how a leaf appears green. When you print it on paper, you see a color that looks natural, just like how you would look at a tree in the park.

For example, bands 3 (red band), 2 (green band) and 1 (blue band) of LANDSAT TM images are assigned R, G, and B colours, respectively for displaying the TCC.

In TCC images, each band is assigned a specific color that reflects the human perception of that color. The bands are typically assigned as follows: band 3 (red) corresponds to red, band 2 (green) corresponds to green, and band 1 (blue) corresponds to blue. This band assignment is crucial for accurately visualizing features on the Earth's surface like vegetation, water bodies, and built environments in a manner similar to how the human eye would observe them.

Imagine you are looking at a garden. The flowers appear in various shades of red, the leaves are green, and the sky above is blue. TCC images enable you to see the garden in colors that are exactly what you would see if you were standing there, helping environmental scientists or urban planners analyze the landscape easily.

The TCC image resembles closely what is normally observed on Earth surface by the human eyes, e.g., vegetation would appear in different shades of green colour.

TCC images are distinct because they closely represent reality. Vegetation appears in various shades of green based on its health and type, which allows for effective monitoring of environmental conditions. In contrast, other forms like False Colour Composite (FCC) images can display colors that do not correspond to real-life appearances. This can be beneficial for specific analyses, but may confuse those looking for straightforward, visual interpretations.

Consider using Instagram filters. A TCC is like the 'normal' filter that presents your friends in the colors they actually are, while an FCC is like using a wild color filter that changes everyone's complexion, which can be fun but not true to life. Scientists often prefer TCC to present accurate information.

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