Contrast Masking

You may now wish to localize the effect of this curve to only a certain area of the image. Do this by painting on the mask for the curve adjustment layer.

Paint on the adjustment layer mask to further localize the curves adjustment n.r^ : ri' * n \: (afepflj

Paint on the adjustment layer mask to further localize the curves adjustment

Contrast Masking is a technique that is typically used in the darkroom to reduce the contrast of a print and make it fit within the tonal range of photographic paper, but it also has the added benefit of increasing highlight and shadow detail, and increasing apparent sharpness. Contrast Masking is especially useful for reducing the contrast of an image while maintaining sharpness - a good contrast mask keep the image from looking mushy when reducing contrast; reducing contrast using the curves tool often results in a flat, unappealing image.

1 Create a new Merged Image layer on which to perform the Lens blur (page 24). If you only have a background layer, duplicate it by selecting Layer>Duplicate Layer.. Name this the "Contrast Mask" Layer.

2 Desaturate the contrast mask layer; Image>Adjust>Desaturate. This converts this layer into a monochrome image.

3 Invert the contrast mask layer; Image>Adjust>Invert. This turns the contrast mask into a negative of the original image. The same basic idea of a traditional contrast mask.

4 In order for this mask to affect the original image, we need to blend it with the lower layer. Change the blending mode of the contrast mask layer to "overlay". This brings detail back to the highlights and the shadows. The change in contrast is apparent, but overall the image appears flat in areas.

5 If we soften the contrast mask, we can restore some of the original detail of the image, in fact, this acts as an unsharp mask, increasing the local contrast and making the image appear sharper. Select the contrast mask layer and blur it; Filter>Blur>Gaussian Blur. The amount of the blur depends on the image; adjusted to the

maximum value that still retains the increase in shadow or highlight detail. For this image, I used ~10 pixels.

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