note that, the same technique can be done / adapt use with Photoshop too.
1. let’s say you have a rectangle image similar to what i have here.
2. Create a rectangle using “rectangle tool”. you will make this rectangle as a drop shadow for the image.
3. in the “properties”
-change its color to black
-opacity : 25
-add “glow” filter, and change its color to black. i sat its size to 5, opacity : 65%, glow : 12, offset : 0
(if you use Photoshop, you might want to use layer effect’s outer grow here.)
4. use “Pen tool” and add an anchor point somewhere in the middle of the bottom part. Don’t let go the mouse!
now hold down “shift” key and drag mouse to the left or right to create tangent line.
5. now move the middle point up a bit.
6. next move the drop shadow rectangle up / below your image, and adjust its left right and top border to go behind your main image. also adjust its opacity and glow filter as see fit.