4. Now we’ll use a filter to make your image look like a screen print. Select Filter, Artistic, Cutout and adjust the sliders to adjust the effect. You can always undo (Ctrl, Z) the step if necessary. Duplicate your file by hitting File, Duplicate, then save it with a new name. Repeat this process twice to produce four identical images.
5. Select one image and click on the arrow in the Layers palette. Select New Layer and hit ok. Double-click the colour box at the bottom of the toolbar and select a new colour. Choose Edit, Fill Layer, then hit ok. Change the selection in the Layers drop-down menu from Normal to Screen. Finally, select Layer, Flatten, then Save.
6. Repeat step five for all copies, choosing a different colour each time. Create a new canvas from File, New, New Blank File (enter the measurements 20x20cm at 300 pixels/inch and select ok). Now simply drag each of the four pictures on to your new canvas with the Move tool, flatten the layer and hit Save.