The abstract watercolor
Abstract painting is not just about the rich colors of oil paint. Many Modernist artists, like their predecessors, test compositions and work out ideas in watercolor. Some artists even prefer its apparent simplicityso much so that they make watercolors their finished work.
In general, watercolors are much less detailed than a photograph's precise record of a scene; colors are subdued and tend to wash together. Forcing a photograph to imitate a Modernist watercolor is likely to involve simplifying it by merging its colors, so choose pictures with clearly defined areas that will be able to accept a lot of Photoshop painting and filters. This is another effect that benefits from being printed on art or textured paper.
I felt this picture's structure could take a Mark Rothko-style blocks-in-the-sky treatment and still echo John Marin's coastal pictures.
Open the starting image. In the Layers palette, click the "Create new fill or adjustment layer" icon and select Curves. Click a point on the curve and drag it upward, making the image much brighter.
Holding down the Alt/Opt key, select Merge Visible from the Layers palette's menu.
Select an area of the image and enter Quick Mask mode (shortcut Q). Select Filter > Blur > Gaussian Blur and adjust the radius to soften the selection's edge.
Select the Brush tool (B) and choose a brush with an interesting texture via the Brush Preset picker. The Dry Media set of presets is great for adding effects.
Match the brush's size to the area, switch its blending mode to Soft Light, and reduce the opacity. Then paint in the selected area with black. Here I painted three large squares and added a single smaller square to the bottom-right of each one.
Once you've finished painting an area, it needs to be made simpler or more abstract. Try the blur filters, or Filter > Noise > Median. Here I used the Median filter, and for areas like the sky, which I wanted to solidify, I used a high Radius value. Use lower values where you want to retain more detail.
Repeat this process with other image areas. Where the wave is breaking, I only used a low Median filter radius; elsewhere I varied the effects, drawing some lines on the shingle and in the sea.
Next go to Filter > Artistic > Watercolor, which saturates the colors near edges. Apply it to each selection, or release the selection and use it to give a common appearance that reunifies the image after the various painting effects and Median filters.
If you wish, try painting some indistinct shapes freehand. Here I used a small, soft-edged brush and set a low opacity, then added a few lines to hint at a yacht.
For a finishing touch, add a soft white border. Place a new layer at the top of the layer stack and use an interesting brush shape to paint white around the layer's edges. Here I clicked in a corner, then held Shift and clicked the next one, and continued around the image.
A series of Photoshop filters simplified and abstracted this picture's main areas before the Watercolor filter applied an overall wash of soft color.