Is “spend (a lot of) pixels” becoming an idiom?

I found the expression, “spend a lot of pixels” in the article titled “Handicapping the Veepstakes: Romney’s Rules of the Road” in today’s (April 25) Time magazine. It begins with:

“We’ve spent a lot of pixels analyzing some of Mitt Romney’s vice presidential options. There’s a reason for this, and it’s not simply because surveying the field and weighing the candidates’ strengths and weaknesses is a popular parlor game.”

I remember that Mitt Romney once mentioned “waste trees” to mean “waste papers.” What does ‘pixels’ represent for here? Is it TV time, or PC usage (for analysis)?

Is “spend a lot of pixels” a received expression today, or just the Time writer’s purple verse?

I'm not sure on what basis you would think this is a common phrase. It is a picturesque metaphor, but doesn't move the needle in the NGRAM viewer. (I have never heard it before, either.)

But that doesn't make it a meaningless phrase. You are on the right track, comparing it to dead trees. (News printed in newspapers tends to create a lot of dead trees. For some types of news, some people would consider this a waste of paper or dead trees.)

It holds a hint of irony, because "pixels" are not physical in the same sense that paper and trees are, so they can't be literally wasted in the same way. But it does convey that there is a waste. One similar phrase I hear in my business is "wasted bandwidth". This can be literal or metaphorical, meaning "waste of time".

The writer is referring to how much attention has been paid by TIME on Romney's campaign. Since that article series is web-only, it refers specifically to the visual medium used to pay the attention - pixels on the web.

This is not a received expression (though it could be gaining traction), it is as you say the writer's purple verse/prose.