Color matching with "Magic Palette"

I'm not the first to use the "Magic Palette" to match colors, but I found a neat Photoshop trick I thought I'd share. I started with a picture of the MP on the playfield in good lighting:

Next, I created a swatch of the playfield color, using the marquee tool, and then I cut a hole in the middle of the swatch (again, with the marquee tool). This is what it looks like (it's in the middle of the picture):

This "playfield swatch" is in a different layer, so I could drag it anywhere without changing the rest of the picture. I moved it around until I found where it was hardest to see. It just about disappears into the square to its bottom right:

Then I just noted where this color was on the grid. It's the 16th column on the "dioxazine purple" row, which corresponds to "phthalo blue". 

Now I've got a choice: I can carry my MP chart into the art supply store to look for a good spot color match, or I can mix these 2 colors from a set of 36 Liquitex artist color acrylics I picked up at Sam Flax for less than $40:

I'm cheap, so I'll try mixing first. I'm also curious to see how well the Magic Palette works. More soon!