I stumbled across today's beautiful color pastel effect while examining a photo submitted by JJ Raia. When I posted Workbench 244 which featured JJ's photo, several viewers asked how JJ achieved the painterly look. Although I don't know, I suspect that JJ used the Soft-Glow Montage technique that I cover in Workbench 134, but perhaps employed Overlay blending mode rather than Multiply.
For the most satisfying color pastel results, begin with an image that features hundreds of small, colorful details, such as fall foliage or flower blossoms. You'll find this technique similar to the Soft-Glow Montage technique in many ways, but with one modification and two additional steps.