Out Steganograph Me!

Question

Out Steganograph Me

As a follow up to this challange, I want to see competitive algorithms for encoding strings as images, and then decoding them.

The Challenge

Your goal is to write a function or program that when given a string as an input, outputs an image. Then, in a seprate program/function, accept that same image as input, and output the string first given.

This should work with any arbitrary string, assuming it is in your chosen character encoding.

You may take input as an array of characters or bytes if it makes it easier, and you may output as a three dimensional array of bytes, or a two dimensional array of hex strings, instead of an image, as well.

Scoring

This is code-challenge, your score will be based on your average score across the test cases.

Individual test cases are scored by taking which of the two dimensions are larger of the output Image, Width or Height, to encourage square instead of lines or rectnagles.

eg, a 5x8 image has a score of 8. A 9x9 has a score of 9, and a 1x30 image has a score of 30.

Lowest Score Wins!

Example for Clarity

A basic algorithm which assigns each UTF-8 Character to each of the RGB channels of an image. so H becomes the r of the first pixel, e becomes the g and so on.

1. Score 3

Actual:

Expanded:

2. Score 6

Actual:

Expanded:

3. Score 4

Actual:

Expanded:

4. Score 1

Actual:

Expanded:

Average = (3+6+4+1)/4 = 4.6666667

Test Cases

• Hello, World!
• This was a triumph. I'm making a note here, HUGE SUCCESS! It's hard to overstate my satisfaction.
• Multiline Strings Usually Cause Problems
• !

Rules

• Standard IO Rules Apply
• Standard Loopholes Apply
• You may use any form of Character Encoding for your String Input/Output, however, it must support the entire visible range of Ascii, and your programs must support the entirety of it. EG. UTF-8 Must support ► and such.
• Control Characters that do not effect the visible output of your string, eg. NUL will not appear in your input.
• Predefined Compression or Decompression functions are forbidden, as it defeats the Porpoise of the challenge.
• Trailing characters after the decoded output are acceptable, although discouraged.
• Have Fun!