By Ian Johnstone

This article explains the technique used in Photoshop to convert a regular photograph into a colourful digital manipulation I call the "Solarization Line Effect".

"Old Truck" to "Big Blue Blast from the Past"

The first stage of the conversion process is to create a duplicate of the original image and apply the solarization filter to it. This is what converts the light yellows and greens of the paint of the truck into the rich blues of the finished product.

Truck with Solarization Effect Applied

Note: If you are following this as a script, you will have to create two duplicate layers. The first gets the solarization effect, and the second is used for Find Edges (see below).

The next stage is to create a second duplicate layer of the original image and apply the "Find Edges" filter to it. This is what creates the lines that overlay the final product. The results of the filter are shown in the image on the left (below).

Find Edges Filters

Next you make two additional copies of the new layer created by the "Find Edges" filter.

The mode of the first layer, the one closest to the layer with the solarization effect, is set to "Exclusion" and the layer above it is set to "Difference". Viewing these two layers in Photoshop produces a black result, but if you place the two layers against a white background, you can see how this intensifies the black of the find edges, as seen above.

In comparison, you could create 3 duplicated "multiply" layers to get the same darkening effect on the lines; however, "multiply" seems to create some noise in the lighter areas of the image, creating a "muddy" texture. As a result, the lighter areas don't look as good as the Exclusion/Difference combination. Experimentation by you might yield better results.

As a result, when shown with the Solarization, these two layers produce the result shown below. As you can see, the image is rather dark.

Solarization + Find Edges

Make a duplicate of the "Difference" layer and set its mode to "Overlay." This serves to brighten the overall image revealing the final result. The nice thing about the Overlay mode setting is it only brightens the areas that are light coloured. As a result, the edges of the truck and grasses remain dark while the blues and sky are the things t hat glow in intensity.

And voila... the Big Blue Blast from the Past.

Solarization Line Effects

As rich as this image is, my favourite part of the image is how the effect alters the intensity of the wood.

Intensity of the wood created by the effect

If you don't include the Difference/Exclusion layers, you get an entirely different result.

Although the result is nice, it is lacking the line effects on the grasses that draw your eye to the truck.

Solarization + Overlay w/o Difference/Exclusion

Two Other Examples

You will find this technique only works on about 5% of the images, usually those where a colour solarization effect works well. In many cases the result of this technique is just plain awful.

Here are a couple of examples where the effect works very well.

In the abandoned house shown below, the effect makes the shack's side closest to the camera too dark, as shown in the cutout. To fix the problem, I highlighted the area in the original area and darkened it. Next I applied the effect and finally merged the two images for the final result.

Except for some minor edits to get rid of cloud protruding from the left side of the chimney, the image is as photographed.

The shack and abandoned truck shown below were less than 30 meters apart. The same effect was applied to the truck except that hue/saturation and brightness/contrast adjustment layers were added to increase the saturation and brightness.

Other than removing a piece of rubber hanging in the middle of the cab - which was a distracting element - the image was left as photographed. You should notice that the colour of the foreground grass and that of the background boards are nearly identical, but in the finished result, they are completely different. This occurs because of the individual blades of grass. The Find Edges filter creates several strands of black which colours the grasses black. If you look closely at the grass you'll see bits of blue shining through.

That's all there is to the technique. Hopefully you'll be able to apply this technique to some of your images and produce wonderful results too!