Named after Michael Orton, two overexposed slides are sandwiched together to create impressionistic, soft, dreamy images. These artistic images are often called Orton Imagery or Dreamscapes (Andre Gallant).
Here's a recipe for making Orton images in Photoshop.
Open your image.
Lighten the image: Image > Apply Image. In the 'Apply Image' dialog box, set the blending mode to 'Screen' and the Opacity to 100%.
Duplicate the layer: Layer > Duplicate. At this point, you may wish to convert this new layer to a Smart Object. With smart filters you can apply a Gaussian Blur—and any of Photoshop's many other filters—while preserving the original image data. And you can go back at any time to change the settings you've applied!
Blur this new layer: Filter > Blur > Gaussian Blur. A Radius setting of 15 to 50 pixels works well—the higher the pixel setting the more 'painterly' the final image.
Change the blending mode of this layer from 'Normal' to 'Multiply' and the Opacity to 50%.
If you like your new image, save the file: File > Save As > Format > Photoshop.
Here's the full version of the slices shown above. This car is hanging in a tree just off the Mokulele Highway (Route 311) near the Maui Raceway Park. Some of the branches have grown through parts of the car's frame. It looks like it's been there a long while but how it got there is a mystery—I can't imagine how a young tree would find the strength to lift it from the ground.
For this image I chose to lighten only the duplicate layer, resulting in a deeper saturation of color in the final image.