1. Set up basic contrast
Open up your image. The contrast on this one looks a little weak, so the first thing we’re going to do is ensure there’s a full range of tones from black to white. Duplicate the Background (Ctrl/Cmd+J) and then run Image>Auto Contrast.
2. Add the reds
Now we’re ready to start creating our light leaked colour. Add a Levels adjustment layer and select Red from the drop-down menu instead of RGB. Push the white slider on the top ramp to 200 and similarly move the black slider on the bottom ramp to 200.
3. Add the yellows
We’ve now added our red: next select Blue from the menu and move the black slider on the top ramp inwards to 100 and the white slider on the bottom ramp to 150 to add our yellow. The different figures for the settings ensure some areas are redder and some more yellow, emulating the read effect.
4. Incorporate some fade
The area containing the light leak is normally a little faded in tone as well as containing the colour cast we have just created. We can apply this lightening effect on the menu and move the black slider on the bottom ramp to 20.
5. Select the Gradient tool
Okay, we’ve now got the task of localising the light leak colour that’s sitting on our adjustment layer to specific parts of the photo. It normally comes in from the corner or edge of the frame, and the gradient tool is perfect for ensuring a subtle rendition. Press G to access this tool.
6. Set up the Gradient tool
Now select the first of five icons in the Options bar (Linear Gradient) and click the gradient ramp drop-down menu. The Gradient Picker will appear. Choose the first swatch (Foreground to Background). Hit Enter and press D to reset the colour swatches to black and white.
7. Click, drag and release
With the Levels layer mask active, you need to click, drag and release to apply the gradient to the mask so that the light leak colour is localised. The area behind the first point where you click receives the full force of the adjustment and everything beyond where you release receives none. The area you draw in-between represents a gradient transition according to the option selected.
8. A gradual fade
It’s worth playing about to see how this works. To create a gradual fade from the edge to the model, click from the left edge and drag to the model’s face.See how this gradient is represented on the layer mask in the palette.
9. Sharper transitions
Now try again, starting from halfway between and finishing in the same place. The gradient is much sharper and the colour extends further into the shot. Notice the difference on the layer mask. Experiment with different length lines, starting and ending at different points. Try it from the corners too.
10. The finished effect
When you’ve hit upon a gradient that you like and that’s appropriate , you can control its stength using the layer Opacity slider in the Layers palette. We used a gradient from the image edge to the face edge and dropped layer Opacity to 60% for a more subtle result.
11. Blue shadows
We’re going to finish by throwing in a bit of a colour cast to give the image even more of a retro feel. Add a Levels adjustment layer and position it under the light leak Levels layer. Select Blur from the drop-down menu and push the black Output slider (bottom ramp) up to a setting of 70 to add a nice blue tone to the shadows.
12. Yellow highlights
Finally, move the white Output slider (bottom ramp) into a setting of 230 to add a little yellow to the highlights. Just finish with a bit of sharpening: zoom in to 100%, select the duplicate background layer and run Filter>Sharpen>Unsharp Mask. Set Radius to 0.5 and choose an amount you think looks appropriate.
