It should go without saying that shooting a photo in the style of the 40s in the first place will make the end result look far more authentic. If you want to see how to do that then check out our article here
There are some signature effects that we're looking to create here. One is that because of the film emulsion, skin tones should come out slightly darker than normal and that lips should be rendered very dark. The other thing is that because tungsten lighting was normally used, the overall light level wasn't that high, so there a shallow depth-of-field. This wasn't always the case, but it's worth including here. The picture should be softer than a modern digital image, and the picture should be retouched. Yes, because the old studio photos were shot on large plates, they were big enough for retouchers to manually clean up images. The classic Hollywood portraits of the 30s and 40s were extensively retouched.
STEP BY STEP
1. The first step is to convert to black and white so go to Image > Adjustments > Black and White. If you aren't using PS3, then the Channel Mixer should be used instead. Enter values of 0% for Red, 60% for Yellow, -200% for Magenta and 50% for the others. The Red component sets the skin brightness, the Yellow stops it from being to freckly, while the Magenta makes the lips darker. The other colours have little effect in this image.
2. The next step is to clean up blemishes. Select the Clone stamp brush and set the Opacity to 100% and the Blend mode to Lighten. Use this to clone from the side of any blemishes, over the top. Then change the Blend mode to Normal and reduce the Opacity to 20% and soften lines under the eyes. You can do as much face sculpting as you like. I've gone a little mad here and overdone it so you can see the effect possible.
3. Next, let's soften the picture slightly. Create a duplicate layer and run a 2 pixel Gaussian Blur on it. Add a layer mask from the Layers palette and select the Paintbrush with black as foreground colour. Set the Opacity of the brush to 33% and paint over the eyes and lips to bring back some detail into them.
4. Merge the layers and then create another duplicate layer. Apply a 6 pixel Gaussian blue to this and add a Layer mask as before. Now mask off the face so that it isn't any softer, edging back up into the hair. Make this a smooth progression so the focus falls off. Use the Paintbrush at 33% and bring a little detail back into the very front of the blouse and arm on the right.
5. Digital images are far too clean. Add some grain and texture by going to Filter > Distort > Diffuse Glow. Set the Graininess to 4, the Glow Amount to 0 and the Clear Amount to 20.
And here's the final image.