Step-by-Step guide
for my TrekLens friends ;-)
Step 1 : Open your picture in Photoshop, duplicate your layer (change the name in "Layer2") and desaturate it (Image >Adjust > Desaturate (Maj + Ctrl + U).
Step 2 : Now, duplicate "Layer2" (change the name in "Layer3") and push on CTRL + I to invert colors.
Step 3 : Change the Blend Mode of "Layer3" in "Color Dodge", your picture is now white, it's normal.
Step 4 : Finally, click on : Filter > Blur > Gaussian Blur, adjust the size of the filter according your image.