How to apply Gray-Scale filter?

[H1manshu21]

Discuss algorithm on how to apply gray-scale effect on BMP image.

[chandrakant100]

Original Image V/S Grayscale image

[SHembram18]

Algorithm for grayscale
https://www.johndcook.com/blog/2009/08/24/algorithms-convert-color-grayscale/

[H1manshu21]

This is a good start to know how to show the intensity or scale of gray-scale.

[Ank1taS]

According to the article given by @HembramBeta777 this
there are 3 different algorithms for Grayscale effects.

Applying 3 different algorithms over an image

Original image

Grayscale - lightness algorithm

Gives a lighter effect

Grayscale - average algorithm

Grayscale - luminosity algorithm

Somehow luminosity algorithm doesn't work properly

[H1manshu21]

Consider this answer in another section and not in the reply section.

[Ank1taS]

By applying the Grayscale effect the original image will convert to a black and white image.

In GrayScale effect all channels (red, green, blue) of a pixel have a specific value that, results in gray and according to this value, various shades of gray a pixel can have. Higher values mean lighter shades (closer to white) and lower values mean darker shades (closer to black).

There are different algorithms for Grayscale, however here is an illustration of Average algorithm
In the average algorithm, in a Grayscale image, each pixel's red, green and blue channel contains the same value i.e the average of the 3 channels of the original image.

Example of Original Image vs Grayscale Image

Pseudocode for Grayscale filter

function reflection (Argumen1t rows, Argument2 columns, Argument3 pixel 2Darray ) {
        iterate and pick each row of the pixel 2D array
                iterate and pick each pixel of the row picked above
                        calculate and store the average of 3 channels (red, green, blue) of the picked pixel. 
                        store the calculated average value in every channel of the pixel.  
end
}

[H1manshu21]

Accepted to go with the average grayscale rather than the rest of the 2 gray-scale options. What do you think? @chandrakant100 @sabyasachi07 @Tushar7-coder @HembramBeta777

[SHembram18]

yes the average grayscale looks better than other two.
@Himanshu40