Color correction on poor quality images - part 1

Left image is our source image, really bad colors.
We gonna change it into the right picture.
I picked a image of a colorfull clown. I think it makes this tutorial more clearly.

ALWAYS start with an copy of the background image.
Layer -> duplicate layer

Create new fill or adjustment layer.
Click on the ball (black and white icon in the layerpalette) and then threshold.
We are now going to define the colors black and white.

move the slider to the left till you see black spots in the image.
You can use the mouse, or the up and down arrow.
I always use the arrows.
Now go with you cursor in the image.
Hold shift and click on the black spots in the image.
There is an spot coming up with the number "1"
Those spot called "samplers"
After that do NOT hit OK or cancel.
First go further with the next step

Now the white colors.
Just do the same as the black.
Move the slider to the right till you see white spots in the image.
Hold shift and click on the white spot.
There is a sampler coming up with the number "2".
Thus there are two samplers.
The "1" for the black color and the "2" for the white color.
Now hit CANCEL.
DO NOT HIT OK !!!