1. Open Image in Photoshop
3. Next choose “Select > Select Inverse” in the top Menu. Then enter “Quick Mask” mode by clicking the camera icon on the bottom left.
4. On the top menu bar, select “Filter > Blur > Gaussian Blur.” A menu box will appear where you can make your adjustments. The more blur you add, the more smooth the transition of light to dark will be in your vignette. Exit Gaussian Blur (click “Ok”) and Quick Mask (Click the camera icon again) when you’re done. (The edges should already be selected when you exit “Quick Mask.”)
5. At the top menu again, select “Image > Adjustments > Levels.” In your Levels box, use the top center arrow to darken the outside of the image, making your vignette. Moving the slider to the right will darken the edges, and moving it to the left will lighten it. Make sure “Preview” at the bottom right of your Levels box is selected so you can see what your image will look like.