I recently came across an article that appeared in Shutterbug describing a method for using Photoshop’s layering ability to adjust the contrast of an image. I started playing with this method and found that it could be used to give the photographer a tremendous amount of control over how the final image looks, and alter the final image so that it appears more like what was visualized rather than what was just recorded. Having learned such a useful method, I decided that it needed to be shared.

To demonstrate the method, I’m going to use the following image (appearing as it was recorded by the camera):

This is an image of the River Seine running through Paris at roughly mid-day. As recorded by the camera, the shadows do not reveal enough detail, the trees along the river blend into the buildings (even though they were a different tone), and portions of the clouds (highlights) are blown out (giving the clouds and overly-white look). Even the detail of the bridge across the Seine—particularly the iron work supporting the bridge—appears to be without detail. Even the people on the bridge are difficult to see.

To alter an image using this technique, load the image—probably a JPEG—into Photoshop. Then, using the Layers toolbox, right-click on the layer entitled “Background” (which should be the only layer you have if you loaded a JPEG) and select “Duplicate Layer…” You will be asked for the name of the new layer; you can accept the default “Background copy” as the name is only needed to identify the layer upon which you will make changes.

Having created a new layer, make sure that you’re working on it by highlighting it in the layers toolbox. Next, you will want to desaturate the image (from the Image menu, select “Adjustments” and then “Desaturate”). This will make the image look like a black and white image. Then you will want to invert the image (from the Image menu, select “Adjustments” and then “Invert”). This will make the image look like a black and white negative as follows:

Once the image appears to be a negative, change the layer’s properties in the Layers toolbox. You will see a box with the setting “Normal” by default; drop down the list and select “Overlay.” This should result in a somewhat strange looking image (almost as if the colors aren’t real). In order to reduce the obviousness of the overlay, select the “Filter” menu, and then “Blur” and “Gaussian Blur.” Now comes the interesting part. The Gaussian Blur tool will open, probably with a starting value of 4.0 pixels. You will need to use the slider in the Gaussian Blur tool until the image on screen appears reasonably close to the way you think it should (reasonably close, because this is not the last step; there's another step that will help blend the layers together). As you increase the pixels, you will see the image looking increasingly like it did originally. Once done with the Gaussian Blur tool, select OK to save your changes. To complete the blending, you will probably need to change the layer’s opacity. This can be accomplished by using the Opacity setting in the Layers toolbox. By default, the opacity is 100%; you will probably want to drop this to somewhere between 50% and 80%. As you reduce the opacity, you will see the image returning more to its original look.

Using this method, the original image was transformed into the following:

In the final version, you can now see the shadow detail in the bridge and the buildings along the river. You can also see the separation between the trees and the building. Finally, the clouds now have more detail. More importantly, the final image appears more like the image I visualized than the image simply recorded by the camera.

One final note: When you try a method like this, do not save over your original image. If you make a mistake, you may need to go back to that. Also, if you're saving the image as a JPEG, you shouldn't save the new (adjusted) image until it is done and ready to print/display. Since JPEG is a lossy compression format, repeatedly saving a JPEG will result in some loss of quality. If you're in the middle of adjusting an image and you want to save your work, you should save the file as a Photoshop file (which will also preserve the layers) rather than a JPEG.