Creating a Posterization Like the Photo Shown Above

1. With color image open change to black/white using Images > Adjustments > Convert to black and white.
2. Change background color to black
3. Increase Canvas size on the left only by 20% using Image > Canvas Size. Put 20 in width box, percent, in adjacent box and check Relative. Alternatively you can use the crop tool to crop the entire image and then drag the left handle to the left about 20 %.
4. Using the rectangle margee tool select a rectangle in the newly created additional canvas.
5. With Default colors drag select the Linear Gradient, Foreground to Background and drag from the top of the selected rectangle to the bottom. Holding the shift key will limit the drag to a straigt line.
6. Image menu > Adjustments > Posterize (near the bottom of the menu)
7. Select 7 levels. This is a level each for the primary rgb colors, the cmy secondary colors and black. This creates 7 boxes of 7 different tones in the selected rectangle.
8. With the Magic Wand, tolerance 0f 10 and Contigious not checked click in the lightest (white) area.
9. Add a new Layer and with this layer active select a color from the Swatches palette. Note that the upper 6 colors in the Swatches palette are rgb and cmy.
10. Use Alt + Backspace key to fill the selected area on this layer with the selected color.
11. Add a new layer
12. Make the background layer active and click on the next lightest color in the tone boxes.
13. Make the new layer active, select another color and fill the selection with the selected color.
14. Add a new layer
15. Make background layer active and click on the next lightest color and repeat steps 13 and 14.
16. Repeat the above until you have selected the 6 tones other than black and filled each layer with a color.
17. Crop your final image.