When you intent to print photos, its often a good idea to lighten skin tones a bit. Dark skin tone can often pose a problem in print. Skin can get a muddy, plugged up look even with a high quality inkjet print. The trick is how to lighten it in a natural way that doesn’t look forced or too contrasty!
Lighten Skin with Channel Blending
Here is a practical application of Channel Blending for a common problem with dark skin tones. Often, the client will want to lighten skin tones so that an image will print correctly or be easier to see details. Here, I’m using an image here by my friend Anthony Nex. He specializes in photography of kids and related products, fashion, advertising and catalog work. He took this great shot of Jordan in the studio – all in all a very good action shot.
Controlling Tone with Channel Belnding
The following tutorial shows how to create a very sophisticated correction that relies on channel blending techniques to control the values in the RGB image (you might want to right-click on the image to save it so you can follow along*). This achieves a result that is impossible to replicate with normal corrective techniques like Brightness-Contrast, Levels or Curves. The ideas in this tutorial build on material in a previous blog post you can find here.
The key here is to look at the individual channels to see if one of the three channels has a better luminosity range than the others. In this case the obvious choice is the red channel. So we will utilize that red channel using a channel blending trick to lighten the dark skin.
Step 1: Start by creating a Channel Mixer adjustment layer:
You can do this either by selecting from the Adjustment Layer icon at the bottom of the Layers panel or by clicking into and selecting from the Adjustments panel directly…
Step 2: Once you have the Channel Mixer layer in place, select “Black & White with Red Filter (RGB)” from the presets drop down menu. If using a different channel in the future, just choose the appropriate preset that matches the channel used.
The result will be a grayscale image representing the Red channel from the color image.
Step 3: Change the blending mode for the Channel Mixer layer to “Luminosity” from the drop down menu right under the Layers “tab” in the panel.
Like magic the skin tone is lightened – but there is a slight problem. Can you spot it?
If you saw the shorts go really dark, give yourself a pat on the back! This would be an easy thing to mask out but there is an easier trick that works like a charm…
Step 4: Double click into the empty area next to the thumbnail (not on the text or you will just edit the name of the layer) for the Channel Mixer layer in the Layers panel and you’ll call up the Layer Style dialog (you can also select “Blending Options” from the Layer options flyaway menu at the upper right corner of the Layers panel)…
We’re interested in the “Blend If” area at the bottom of the dialog. This is a little used but very powerful tool for masking areas of the image based on their luminosity. The gradient on top represents the luminosity of the selected layer and the gradient on the bottom represents the luminosity of the layers underneath. Select “Red” from the “Blend If” drop down menu – we’re now going to use the luminosity of the Red channel to mask off the effect of the channel mixer adjustment.
Step 5: Pull the little black triangle slider at the left towards the center until the blue shorts re-appear.
We’re telling Photoshop to “blend through” to the underlying image everywhere the red channel is black. The blue shorts are black in the red channel and the skin is much lighter so we can easily remove the Red channel effect from just the shorts without painting a mask. Once the black triangle is in the appropriate position hold down the Option or Alt key and pull the two halves of the triangle apart – this will create a smoother transition in the virtual mask!
Now that we have lightened the skin it may seem like the skin color is a little less saturated than we would like. Darker skin tone is less saturated than lighter skin and now that we’ve lighted his skin we might want to compensate by adding a little saturation.
Step 6: Return to the Adjustment panel and click on the left facing arrow at the bottom left of the panel to get to the other Adjustment types. Select the Hue/Saturation adjustment…
Step 7: When the Hue/Sat adjustment comes up select “Reds” from the “Master” dropdown menu – we only want to adjust the skin saturation and skin color is mostly red as far as Photoshop is concerned.
Push the Saturation slider to the right to increase the saturation but don’t overdo it. I felt that +15 was far enough. You can also adjust the Hue slightly if you feel that the skin color is now just a little pink looking – by pushing the Hue slider to the right a tiny bit the skin will get slightly yellower which might work better for the lighter skin color.
So far so good…
We could probably stop now but perhaps, after so much lightening, the contrast may seem a little flat. We could use a curve of course but I wouldn’t really want to affect the T-shirt or shorts with a global curve. So… we will examine an additional technique for “popping” the highlights in the next blog post—stay tuned!