Okay, now it's your turn to work with an RGB image!

Write a program that takes a coloured image and turns it into a greyscale image according to the method described below.

The program should ask the user to enter a filename, open this file, perform the transformation, and then save the greyscale version of the image to the file 'output.png$\text{'}.$

To turn a colour image into a greyscale image, we need to decide on a single colour value for each greyscale pixel $($based on the three colour values from the corresponding RGB pixel$).$ For this problem, we will determine the colour value by simply averaging the red, green, and blue colour values $($and rounding the result down to an integer$).$

Here is an example of the effect your program should produce:

RGB astronaut

astronaut.png

Enter a filename: astronaut.png

Average greyscaled astronaut

output.png

Average colours

The method of averaging RGB colour values to produce a greyscale colour value is flawed. When humans see, our vision isn't influenced by red, green, and blue light equally.

More sophisticated methods perform a weighted average instead, in an attempt to produce an image that looks more close to the original $($but without colour$).$ See this Wikipedia page, for more information.