Rainbow Road Rabbit Hole

This puzzle is rainbow (road)-themed, and consists of a series of colored images. Each image contains the URL of the next image, encoded or obfuscated in some fashion.

Steve Eckert started us off by solving the "red" and "orange" images.

The "red" image (the image in the OP) used a traditional steganographic technique:

The "orange" image uses a classic encoding method:

f'' was next to step in, solving the "yellow" image:

This revealed the "green" image:

This image contains a number of barcodes. Each of the barcodes on the first row encodes a single character from the URL:

This gives us all but one of the characters in the URL. Brute-forcing the remaining character by programmatically trying all 62 possible characters leads us to the "blue" image:

We can see the letters p, n, and g on the right, so it's apparent that we must rearrange the letters using the values on the left in order to retrieve the next URL.

I'm too impatient to figure out what $B'_L$ and $beta$ are, so I programmatically searched all 120 permutations of the right-hand side that ended in .png, leading to the "magneta" image:

The next URL is encoded with a simple

Using a known-plaintext attack on the extension (.png), we get:

I wasn't sure how the cipher was supposed to affect the digits, so I once again brute-force searched all 100 possible digit assignments, which turns up (along with two false positives) the "purple" image:

You can tell that we're dealing with a transposition cipher, since all the characters from the expected URL format (http://i.stack.imgur.com/*.png) are here. Playing around some reveals that it's a simple

Note that in order to decode it correctly, some of the spaces in the text have to be doubled or trebled. With the correct spacing, I get:

Y       s i a t . i o 9
o a t H   n g t s m m .
u l h e t a e p t g / j
  m e r h l : : a u 5 p
a o r e e     / c r Y g
r s e     i   / k . 8
e t . i f m h i . c u 

or:

Yielding the final part of the puzzle:

In the spirit of the challenge, I'll present the answer as an image of my own: