How to Blur a Background in Lightroomby Christopher Kennedy ; Updated September 28, 2017
Getting your camera settings correct in the moment is a difficult thing to do when the picture is spontaneous or too many other variables exist. Luckily, Adobe Lightroom allows photographers to tweak and adjust many aspects of their digital photos to get the look they want even after the camera has finished doing its job. One of the adjustments that can be made is blurring the background of a photo to give it that professional touch it may have been lacking.
Open Lightroom and select the image with the background you wish to blur.
Click the "Develop" link in the Lightroom toolbar at the top right of the window.
Press "K" on your keyboard to select the "Adjustment Brush" tool. You can also select the tool by clicking the right-most icon underneath the RGB Histogram.
Adjust the "Clarity" slider to a negative value by sliding it to the left. Alternatively, you can also adjust the "Sharpness" slider and see which variable gives you a better overall look.
Hover your mouse over the image and click where you want to begin painting your adjustment brush. Repeat using the brush tool until the entire background is blurred, and avoid painting on any foreground objects that you want to remain sharp.
Click "Done" to exit the "Adjustment Brush" editing mode.
Use the "Erase" option under brush settings to undo any mistakes you may have made. Make sure the "Auto Mask" feature is checked to help avoid painting any foreground objects that need to remain sharp. Hovering over the grey circle that appears on the image while the Adjustment Brush is enabled will show you a quick mask of the areas that have already been painted. The "Sharpness" and "Clarity" sliders can still be edited even after you are done painting to adjust the effect to a desired result.