Smoothing Skin with Luminosity

Topics Covered in This Photoshop Tutorial:

The Channel Mixer Adjustment, Using Channels to Smooth Skin Tones, the Luminosity Blending Mode

Exercise Preview

Exercise Overview

Professional photographers and retouchers have long understood a fundamental principle of skin retouching: the red channel consistently delivers the smoothest skin texture with minimal blemishes and pore definition. This technique leverages Photoshop's Channel Mixer in Luminosity blending mode to strategically blend these smoother red channel tones into your portraits. The result? Natural-looking skin smoothing that maintains authentic texture while eliminating harsh imperfections—a cornerstone technique for high-end portrait work.

Looking at One Image

1. Open yourname-WhiteShawlWoman.psd if it isn't still open.

2. Hide the smooth skin layer group.

3. Select the Background layer.

4. Examine each color channel individually by pressing Cmd–3, 4, 5 (Mac) or CTRL–3, 4, 5 (Windows) to cycle through Red, Green, and Blue channels respectively.

   Notice how the Red channel reveals significantly smoother skin tones with minimal textural variation, while the Green and Blue channels show more pronounced pore structure and surface irregularities. This phenomenon occurs because skin naturally reflects more red light uniformly, creating less contrast in surface texture. However, in this particular image, even the red channel shows considerable forehead texture, making it a poor candidate for this technique.

   This principle mirrors traditional black-and-white photography, where photographers used yellow, orange, or red filters to emphasize the smooth red component of skin while suppressing the texture-heavy green and blue information. We're applying this same concept digitally by replacing the luminosity information from the Green and Blue channels with the superior data from the Red channel.

Since this current image doesn't showcase the technique optimally, let's work with a more suitable example that better demonstrates the power of channel-based skin smoothing.

Smoothing the Skin in a More Suitable Image

1. Close this file without saving changes.
2. From the Photoshop Adv Class folder, open PinkTankTopGirl.psd.
3. Save it as yourname-PinkTankTopGirl.psd.
4. Navigate to the Channels panel and carefully examine the skin texture across all three color channels. You'll immediately notice the dramatic difference—skin blotchiness and texture are virtually absent in the Red channel, while clearly visible in the Green and Blue channels. This makes it an ideal candidate for channel mixing techniques.
5. Select the composite RGB channel to return to full-color view.
6. Choose the Lasso tool and create a rough selection around the woman's face. Precision isn't critical at this stage—we'll refine the selection next.
7. Navigate to Select > Select and Mask to access Photoshop's advanced selection refinement tools.
8. In the Properties panel, click the view thumbnail and double-click On White for optimal edge visibility.
9. Set Opacity to 100% for maximum contrast against the white background.
10. In the Global Refinements section, apply a subtle Feather of 2-3 pixels to ensure smooth edge transitions that won't create visible selection lines.
11. Click OK. Don't worry about protecting eyes, eyebrows, mouth, or hair at this stage—we'll address these areas with targeted masking.
12. Choose Layer > New Adjustment Layer > Channel Mixer to access our primary smoothing tool.
13. Name the layer smooth face and—this is crucial—set the blending mode to Luminosity. This blending mode ensures we're only affecting the brightness values while preserving all color information, preventing unwanted color shifts that could make skin look unnatural.
14. Click OK to create the adjustment layer.
15. In the Properties panel, enable Monochrome to work with luminosity values exclusively.

16. Configure the channel sliders to isolate the Red channel information:

    Red:	100%
    Green:	0%
    Blue:	0%

    The Total should read 100%, ensuring proper luminosity balance. You'll immediately see smoother skin texture, though it may appear lighter and flatter than desired—this is normal and easily corrected.

17. If the selection edges create visible boundaries, select the Layer Mask of the smooth face layer and paint with a soft, low-opacity brush to blend the edges seamlessly into the surrounding areas.
18. With the layer mask still active, paint with black over critical facial features—eyes, eyebrows, lips, hair, and any overexposed highlight areas. This preserves the natural detail and prevents the artificial "plastic" look that occurs when these areas are over-smoothed.
19. Now we'll restore natural contrast and luminosity to the smoothed face. Ensure the smooth face layer is selected.

20. Create a targeted adjustment by choosing Layer > New Adjustment Layer > Curves with these settings:

    • Name: face brightness & contrast
    • Check Use Previous Layer to Create Clipping Mask to limit the effect to our smoothed area
    • Set Mode to Luminosity to maintain color integrity
    • Click OK

21. Create a subtle S-curve to restore natural contrast and skin luminosity, as demonstrated below:

    

    The curve should gently lift the highlights and deepen the shadows to restore dimension while maintaining the smooth texture we've achieved.

22. Save your work and close the image. You've now mastered a professional-grade skin smoothing technique that maintains natural texture while eliminating unwanted imperfections.