In Photoshop, go to Filter > Distort > Polar Coordinates > Polar to Rectangular.
Next, go to Image > Rotate > Flip Vertically.
Next, go back to Filter > Distort > Polar Coordinates, but this time click Rectangular to Polar.
That's it. For added fun, play with Hue/Saturation, or change the Image Size to square.
If you like photographing tulips and playing in the digital darkroom, check out the workshop that I am doing in The Netherlands in 2011.
Explore the light,