Today’s Question: How do you show dust spots in Lightroom or Photoshop so you can correct it?
Tim’s Quick Answer: In Lightroom it is relatively easy to locate dust spots in your photos by using the “Visualize Spots” option associated with the Spot Removal tool. In Photoshop I generally use an exaggerated adjustment using Curves to help locate dust spots.
More Detail: The Visualize Spots option provides a tremendous advantage for locating dust spots in Lightroom. Once you have selected the Spot Removal tool, you’ll find the Visualize Spots checkbox on the toolbar below the preview image. If the toolbar isn’t present, simply press “T” on the keyboard to enable the toolbar.
With the Visualize Spots checkbox turned on, the image will change to a black and white preview, highlighting contrast edges within the photo. The slider to the right of the Visualize Spots allows you to adjust the threshold for that display. While I generally find that spots are easiest to see when the slider is all the way to the right, I highly recommend dragging the slider left and right through the full range for a more complete evaluation of the image.
Note that you can leave the Visualize Spots checkbox turned on while performing cleanup work on the image. However, you’ll want to be sure to turn off the Visualize Checkbox periodically to evaluate the results you’re achieving are blending in well with the surrounding areas of the photo.
In Photoshop there isn’t an equivalent to the Visualize Spots (although this option is available in Adobe Camera Raw). Therefore, when working in Photoshop I will use an exaggerated Curves adjustment to help find any dust spots present in the image. I’ll simply add a new Curves adjustment layer to be used for this purpose, and then drag the curve up and down for an extreme adjustment. This can help make dust spots easier to see.
As long as the image cleanup tool you’re using ignores the effect of adjustment layers, you can leave this Curves adjustment layer enabled while you perform your cleanup work. For example, the Spot Healing Brush tool this behavior is always active, so you can leave the Curves adjustment turned on without worrying about an impact on your cleanup work. For the Healing Brush and Clone Stamp tools there is a setting on the Options bar that will cause these tools to ignore the effect of adjustment layers. The button for this option is the same basic icon as the half-black and half-white circle icon for the button used to add an adjustment layer.
In addition to using these view options to help you locate dust spots in an image, it is also important to zoom in a little bit to make it easier to see the dust spots, and to review all areas of the photo. I recommend taking a somewhat methodical approach to that review, to make sure you locate all dust spots in the photo so you can remove those dust spots and ensure a “clean” image.