1. Create two layers with the same image in each one
2. Switch off layer 1
3. On layer 2 set layer type to normal, opacity to 90% and fill to 60%.
4. Then on layer two apply the watercolour filter (under Artistic) with the settings: detail = 14, intensity = 0, texture = 1
5. Switch on layer 1
6. Adjust the brightness/contract of both layers to suit
7. Flatten and finish
Should be somewhere close... you could also try the median filter also mess around with layer modes.
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