Before you attempt to start making shadows of your own it is good to know a little about how light and shadows interact. It’s a good idea to look at some photographs and observe when shadows are long, when they are short, when they are blurry, and when they are sharp. A well made shadow in a photo manipulation will give your image a realistic feel and make it look much more professional. A poorly done shadow on the other hand can completely ruin a picture’s integrity. In this tutorial I will describe two different techniques for making two different kinds of shadows. They are both very simple and I am confidant that anyone can make good looking shadows using these techniques. There are probably other ways to go about making shadows as well, but this is what I do, and it works for me.
The bright light, or sharp shadow
On sunny days when the sun is fairly high on the heavens shadows tend to be much more visible and sharper around the edges. They tend to echo the shape of the object fairly well, and the outline is pretty clear. To make a shadow like this is fairly easy, but again, you need to make sure to do it well. Look at how the other shadows on your background image behave and make sure to pay attention to how your horse/human/other animal is lit.
-Duplicate your animal/human layer by right clicking on the layer in the Layer Dialog Window (Dialogs -> Layers) and then selecting Duplicate Layer.
-Rename your layer to ‘shadow’ or something similar. This helps you to keep your layers organized.
-Flip the shadow layer vertically by clicking Layer -> Transform -> Flip Vertically.
-Once that is done colorize the duplicated layer black. To colorize click Filters -> Colors -> Colorify. Then select black as your custom color and click ‘ok’.
-Now that your shadow layer is completely black you will need to make sure that the shadow looks good. You might need to move it or turn it slightly so that it looks more natural. To turn it just click Layer -> Transform -> Arbitrary Rotation. Just mess around with that for a bit until you are satisfied with how the shadow is positioned.
-To make the shadow look more natural and less sharp you will now need to gaussian blur the shadow layer. Do this by clicking Filters -> Blur -> Gaussian Blur. I recommend a blur radius of about 5.
-After blurring the layer you will need to adjust the opacity of your shadow layer until the darkness looks about right. Look at the other shadows on your background to see how dark or light your shadow should be to match them.
And now you are done! You just made yourself a shadow!
An example of a sharp shadow:
The muted light, or soft shadow
When you are using a background picture of a cloudy day or just a background picture that isn’t very brightly lit, you won’t want to add a very sharp or distinct shadow to it. For pictures like this I like to use a different technique. If you are good at freehand drawing then this technique will be pretty easy, otherwise you might find it a bit more difficult.
-Create a new transparent layer and name it something like ‘shadow’.
-Select the paintbrush tool and pick a medium sized brush. Make sure that you are painting with the color black.
-Now paint on your shadow layer a small and slightly shapeless shadow. Remember to look at the rest of the shadows on the background to make sure that you are matching their appearance (direction, length etc.) best you can. Be careful with this, a little shadow goes a long way.
-Now adjust the opacity of your shadow layer until the darkness looks about right. If you think that your shadow looks too sharp you can always try gaussian blurring the layer a little bit.
And there you go, you made yourself another shadow!
An example of a soft shadow:
I hope that this tutorial has been helpful, if you have any questions please feel free to ask. If you would like to show me your results then go right ahead and post them here! Eventually I do plan on adding some screenshots to this tutorial as well, but right at the moment I am not able to do so.