It's just that time of year... (Puzzle finished - Solution inside)

So... It's my birthday today, which of course means I have to give you folks some presents. But as I'm a grumpy old sod, you'll have to work for it.

That's right, it's puzzle time.

The Puzzle

There are 3 giveaways to be found with contributor values ranging from $0.99 to $14.99. They end on Saturday 20th, 13:00 GMT.

It shouldn't be too difficult as long as you figure out where to channel your attention.

Solution

The puzzle link leads you to a picture that is 5 pixels wide (the height was irrelevant, I just made it 100 so people could actually see it), consisting of coloured bars down the length of each of the 5 pixels.

This is the only part that might trip up new members to the site as it should indicate to anyone who knows the usual puzzle format here, that this will probably somehow map to the 5 character code found in a giveaway URL.

The next couple of hints were that there are 3 giveaways and a veiled mention of the word 'channel', referring to the colour channels of the image. These were designed to direct your attention to both the colour values of the pixels and more specifically the individual red, green and blue channels.

The next step you had to work out entirely alone, except for my very obscure hint near the end in reply to a comment requesting hints: "A secret chant is involved", which has the acronym ASCII. So here you were supposed to work out that you now have a 3 rows of 5 colour values, one for each RGB channel, and you want to have 3 sets of 5 characters for the giveaway codes. It is as simple as taking the decimal values you find for each pixel (or hexadecimal or any other equivalent numerical representation, though I only tested standard base 10), easily discovered using colour picking tools in such programs as MSPaint or GIMP, translating them into ASCII characters, and arranging them by channel.

The red channel would lead you to: http://www.steamgifts.com/giveaway/uPcyA
The green channel to: http://www.steamgifts.com/giveaway/iwVOt
And the blue channel: http://www.steamgifts.com/giveaway/u5Eut

Congratulations to all solvers and the giveaway winners.