Today’s Question: I seem to have lost my ability to paint a selection in Quick Mask mode [in Photoshop]. I switch to Quick Mask mode and select the Brush tool, but when I attempt to paint nothing happens. This has worked successfully in the past.
Tim’s Quick Answer: You will most likely find your answer on the Options bar, with the configuration settings for the Brush tool. In particular, confirm the Mode popup is set to “Normal” and than the Opacity setting is at 100%.
More Detail: You can use Quick Mask mode in Photoshop to create or modify a selection using the painting tools (such as the Brush tool) rather than the selection tools. In a very general sense this enables you to paint to define the overall shape of a selection rather than tracing along the edge of a selection. In addition, Quick Mask mode enables you to adjust the brush Hardness setting as you’re working, so you can apply a variable degree of feathering for your selection. You can also adjust the Opacity setting if you need to have some areas partially (rather than fully) selected.
When you are in Quick Mask mode and using the Brush tool, for example, all of the settings that impact the behavior of the Brush tool will impact your results in Quick Mask mode. The result, however, may be significantly different, since in Quick Mask mode you are effectively painting with only black and white (and possibly shades of gray). This can result in blending interactions that have a significantly different impact than if you were painting on a full-color image layer.
The two settings that are most likely to impact your use of the Brush tool with Quick Mask mode are the Mode popup (for the blending mode) and the Opacity setting. In general you will want to have the Mode set to “Normal” and the Opacity set to 100%. But the key is to remember that when you’re using the Quick Mask mode to create or modify a selection, the settings for the specific tool you’re using will have an impact on the results you achieve within Quick Mask mode.
For those who have signed up for the “Photoshop for Photographers” bundle or the “GreyLearning Ultimate Bundle”, you can view a video lesson about using Quick Mask mode in the “Mastering Selections in Photoshop CC” video course on the GreyLearning website (http://www.greylearning.com). The specific lesson is Chapter 5, Lessons 6, and is called “Using Quick Mask Mode”.