Today’s Question: Does the Threshold control in Photoshop’s Unsharp Mask filter do the same thing as the Masking control when sharpening in Lightroom?
Tim’s Quick Answer: The Threshold control for Unsharp Mask in Photoshop and the Masking control for sharpening in Lightroom are very similar in terms of the overall concept involved and the results you can expect.
More Detail: As noted in an Ask Tim Grey eNewsletter last week, the Threshold feature of the Unsharp Mask filter in Photoshop enables you to mitigate the effect of sharpening in areas of relatively smooth texture. In short, the Threshold control enables you to set a minimum level of contrast that is required before the Unsharp Mask filter enhances contrast to create a sharpening effect.
The Masking control that is available with the sharpening in both Adobe Camera Raw and Lightroom’s Develop module provides a very similar feature. By increasing the value for Masking you are requiring that a certain degree of contrast exist before any additional contrast is added via sharpening. In other words, the Masking control defines a threshold similar to the Threshold control for the Unsharp Mask filter.
The context of the question addressed last week was a comparison of the Unsharp Mask filter compared to the Smart Sharpen filter in Photoshop. If you are applying sharpening in Adobe Camera Raw or Lightroom’s Develop module, you can achieve the same basic effect of the Threshold control available for Unsharp Mask by increasing the value for Masking.
Note, by the way, that when increasing the value for Masking in Adobe Camera Raw or Lightroom, you can hold the Alt key on Windows or the Option key on Macintosh to see a black-and-white preview of which areas will still be sharpened versus which areas will not be sharpened. With the Alt/Option key held down, when you drag the slider for the Masking slider the preview image will appear white where sharpening is going to be applied and black in areas where sharpening will be blocked.