Advanced sharpening

Problems with Unsharp Mask Filter

• Sharpens all of the color channels
• Doesn't work well on some photos because it exaggerates noise in one of the color channels
• Increasing the brightness contrast around edges can cause color shifts

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Luminance Based Sharpening 1

• Convert the image to CIELab Color, which has 3 channels:
• A and B channels hold color information
• L (Lightness) channel holds luminance information (black and white image)
• Image>Mode>Lab Color
• Open the Channels palette
• Turn off the A & B channels
• Select the L channel and use Unsharp Mask or Smart Sharpen
• Can experiment with relatively high settings
• When satisfied with the results, change back to RGB color mode: Image> Mode>RGB

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Luminance Based Sharpening 2

• Create a duplicate layer of the image
• Apply Unsharp Mask filter to photo
• Do Edit>Fade Unsharp Mask or Smart Sharpen
• Select Luminosity in the Mode dropdown box
• Adjust the opacity of the duplicate layer in the layers pallete

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Sharpen images with one predominant color

• If an image has one predominant color, the layer which most closely represents that color will be "weak", and the other channels will be heavy
• If you sharpen the heavy (dark) channel or the one that is opposite the predominant color on the color wheel (may have to shift to CYMK color) it will help the image
• Again do this to a duplicate layer and then reduce the opacity of the layer to get the desired result.

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Sharpening Skin Tones

• Applying Unsharp Mask or Smart Sharpen to a face can make emphasize imperfections and make the person look old
• To boost detail in skin tones sharpen only the Red channel
• Even better way is to convert the image to CYMK color mode and sharpen the Cyan and Black channels
• Then change the color mode back to RGB

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