The original shadow was created as black shape on white background. I assume you did the same with your version. The layer structure is simple. Its purpose is to make the shadow available on any background, also on another image, not only on white. The method can be useful in mockup templates.
You can do the same by inverting your shadow and using it as a layer mask for exposure or curves adjustment layer. The adjustment layer is adjusted to make the underlying layer (=the background) darker and the layer mask defines the affected area + reduces the depth. Black = no effect, White=full effect
Do the following:
- invert your shadow (Image > Adjustments > Invert) you need it as white on black
- copy the inverted shadow to the clipboard
- insert a background image behind your object
- insert an exposure adjustment layer just above the background
- adjust the exposure to dark
- add a layer mask to the exposure layer
- select the mask icon in the layers panel and hold Alt key at the same time; this brings the mask to the screen for edits
- paste in place the inverted shadow
- click the image icon in the layers panel
Now the shadow should be effective.
You can do the same with less hassle and without inverting the shadow. Simply place the black on white shadow layer just above the background and give to it blending mode=multiply. Adjust the opacity for good shadow depth.
Actually you do not need white at all, because transparency does the same, if you have a separate background.
Adjustment layer method gives mode adjustability - especially, if you use curves layer ( for example. some weird underlight effects are possible)
How to create the shadow starting from the object:
- create a white layer, you need it as adjustment background
- place a copy of your object layer above the white layer
- goto Image > Adjustments > Curves and make the object copy full black
(its useful now to duplicate the black object and hide it in the layers panel)
- goto Filter > Blur > Gaussian blur and make the black shape fuzzy
- move the original object to the top in the layer stack
- adjust the opacity and placement of the shadow layer
- for extended realism insert another shadow with different blur and different placement. If the other blurred version uses motion blur, very different effect is possible.
Here's an example
Instead of white background any image can be used. The blurred black shadow layers can be a little better with blending mode = multiply. Otherwise someone can see not a shadow, but a different solid grey object because in normal blending grey replaces the color. Blending mode normal works on white and grey backgrounds.
Here's another example (sorry for weird color selection, it happened to be opened in Photoshop):
Finally Motion blur was tested. It created quite sharp edges. They were fixed with Gaussian blur which was applied after motion blur: