Allows adding and retrieving hex codes hidden in pixel RGB

[agalway-r7]

Adds commands for overwriting the RGB codes of the pixels in a given image with a passed as parameter hex code. An complimentary command for retrieving a Hex code in the same manner is also included.

Both commands take as params:

• --img TEXT Image to retrieve hex code from or insert hex code into [required]
• --x INTEGER X Co-ordinate for pixel that hex insertion/retrieval begins with. Defaults to 0. [Optional]
• --y INTEGER Y Co-ordinate for pixel that hex insertion/retrieval begins with. Defaults to 0. [Optional]
• --rgb TEXT 2D JSON Array (3x8) of [1/0] values to indicate which RGB values should be overwritten/extracted. Defaults to the four LSBs of each RGB value. [Optional]

get-hex specific commands:

• --hex_length The length of the hex pattern to be retrieved [Required]

insert-hex specific commands:

• --hex_code hex pattern to be inserted into the image (no delimiters) [Required]

Developed for the creation of the Queen of diamonds challenge in the Metaspolit 2020 CTF.

[kelvins]

Thank you very much for your great contribution. I just added some comments to the code review.

Also, your description in the PR was very detailed, thanks for that. Can you just add a simple example of usage of this feature, please? Just to clarify the purpose of the feature and how it could be used in a real-world scenario.

Thanks

[kelvins]

I'm closing this PR because it is more than a month stalled (without an answer).