Question

Which algorithm is used to convert rgb to grayscale?

Answer 1

The basic 'algorithm' is to find three parameters, ,,

a

,

b

,

c

, and set the gray-level value at each pixel,

y

, as =++

y

=

a

R

+

b

G

+

c

B

.

The naive way to set ,,

a

,

b

,

c

is just an average: ===1/3

a

=

b

=

c

=

1

/

3

. However, in practice this is not the case, and the parameters are based on the human visual systems: we do not see each color as a 'third' of the intensity, but rather we see more green than red and blue.

Empirical research can get a good estimate of these parameters, and the final value is set to (approximately) =0.3+0.6+0.1

y

=

0.3

R

+

0.6

G

+

0.1

B

, so that the single-channel (gray-level) image best corresponds with our perception of color intensities.