Exercise 1

1. Luminosity Method: This uses the coefficients 0.2989 for Red, 0.5870 for Green, and 0.1140 for Blue, which takes into account the human eye's sensitivity to these colors. Generally yields a more visually accurate grayscale representation as it adjusts for human perception.
2. Average Method: Tends to produce a slightly washed-out or less contrasted image since it doesn't consider the varying sensitivity of human vision to different colors.

Exercise 2

I've used KMeans for color quantization. The color quantization has been successfully applied to the resized version of the image, significantly reducing the number of colors to 16, as displayed above.

Exercise 3

Exercise 4