Choose your image
A good photo will:
1. Not be too small in size (greater than 300x300 at minimum)
2. Incorporate art nouveau motif's such as; flowers, long wavy hair, butterflies, dragonflies, draped clothing
3. Not be high in contrast (will need details of face and hair)
I chose this picture of me with purple carnations
Click: Layers > Duplicate
Click: Layers > New Raster Layer > OK
Then on the Layer Pallet switch the order of the Duplicate Layer and Layer 2 by clicking and dragging
Click on the "Copy of Background" layer
Click: Effects > Edge > Trace Contour
Click: Colors > Adjust > Threshold > Set to 255 > OK
Then on the Drop Down list for Copy of Background, instead of "Normal" select "Multiply"
Click on the "Layer 2" in the Pallet
Then select a gradient, I created the one in the picture, just two colors and on a diagonal shape.
Use the flood bucket tool to fill the gradient color on this layer
On the drop down list select "Exclusion", or play around and see what other setting makes your image look cool.
as an option sometimes I select the background layer, then click: effects > blur > Then any of the blur's to soften the original image a little bit.
Click: Layers > Merge > Merge All
Then re-size as necessary and enjoy.
If you try this and like it, I'd love to see how your versions have come out.