Steam & Vapor Tutorial Author - Man1c M0g (http://forums.biorust.com/member.php?userid=1)

In stark contrast to the relatively easy tasks of photo correction and photo manipulation, adding natural elements to your images can be fraught with problems.  Unlike their hard-edged counterparts, steam has an almost ethereal quality which can be hard to replicate, and even more difficult to blend seamlessly into your images.  With the following technique, however, you will learn a simple method for creating realistic steam using nothing except Photoshop's in-built filters and your own internal attention to detail.
 

Step 1: Open up a stock image in Photoshop of any size and/or format. Please note that the image to my right was grabbed from the excellent SXC.HU archive - where there are tons of high quality pictures available for free! NB. When choosing a stock image, remember that steam forms more easily in colder and wetter climates.  Nothing would look more ridiculous than fake steam being formed in the bright sunlight of the desert from something as small as a coffee cup.   To this end you may need to alter the color balance of your stock image to make the light appear colder... but I will leave this step up to you!

Step 2: Using the rectangular marquee tool and with the Feather setting set to 25px, create a feathered section above your object.   Then, with the cursor keys, move the selection into the centre of your canvas.  This positioning is only temporary, and stops your artificial steam overflowing the canvas as it is created, which can cause a massive amount of problems later. NB. The size of the Feather value depends entirely on the resolution of your stock image.  In my example, the image was 650x1000 pixels.  If you have a bigger or smaller image you may want to increase or decrease the size of your Feather value accordingly.

Step 3:  Create a new layer called Clouds (Layer > New > Layer), and make it active in the layers palette. Set your foreground and background palette colors to mid-grey and white respectively.  Then, with the selection from step 2 still active, apply Filter > Render > Clouds. This forms the basis of the steam, but to make it a little more realistic we need to add Filter > Blur > Motion Blur.   Set the Angle to -90 and the Distance to 160px (or more if you have a bigger image).   Press OK to finalize the effect. You should now lose your selection by either clicking on the canvas or selecting Select > Deselect from the main menu.

Step 4:  Steam is, of course, very mobile and moves around with even the lightest of air currents.  To recreate this natural phenomenon we can use Filter > Distort > Wave with the settings on the left.  As with the clouds filter, the results can be highly volatile and it is absolutely impossible to create the exact same shape twice.  My advice is to play around freely with the settings and see what you can create. If you have an obvious source of air currents in your picture (i.e. an open window next to the object that is emitting steam), then you may want to use Edit > Transform > Distort to mimic the effect of massive air movements.

Step 5:  Our steam is looking much more realistic already, but to breathe real life into it we now need to alter the layer blending mode to Hard Light and the Opacity to 90%.  Once you have done this, use the move tool to place the steam back above the steaming object, and then whip out the eraser tool to get rid of any steam which may be overhanging (i.e. in my example, this would be steam showing BELOW the cup's edge).

Step 6:  And here is the finished result!  The effect is subtle yet realistic - just like proper steam! At this point you are finished, but if you want to a stronger and even more erratic steam effect you can go a little further.  To do this, duplicate the Clouds layer (Layer > Duplicate Layer), drop the duplicate layer's Opacity to 60%, and flip the steam with Edit > Transform > Flip Horizontal. Then all that's needed is a little manual adjustment with the Move tool and you have even better steam.