Remember the movie "The Invisible Man" of many decades ago?  (Most SONOPP members have seen the movie, for they are old and the movie came out when they were in college.)  Well, you couldn't see The Invisible Man, for he was invisible and light passed right through him.  But you could detect his presence; for instance, you could take him out early on a foggy morning and see his outline, because the light that passed though his body had less fog to go through.

In Photoshop the equivalent of The Invisible Man is anything that is 50% gray on a Layer in Overlay mode.  You can't see it.  But you can detect it, by giving the Layer a Bevel And Emboss style.  Let's see how that works.

Suppose your photography company is named "Thump Photography," and you want a watermark you can apply to any image regardless of the image's size or dimensions.  First create a new 20x20 image at 300 dpi, much bigger than any image you will ever need to watermark, and select White for the Background Contents.  Now make your Thump Photography logo, as follows.

Press "d" to set the foreground color to black, select the Type tool, and set the font type to Gill Sans Ultra Bold and the font size to 800pt.  Click in the center of the image, type a capital T (for "Thump"), and click the Commit checkmark.  Hold down the Shift key (that's important) and click right in the center of the "T".  Photoshop will create a new Type layer, where you can type "P" and click Commit.  Use the Move tool to drag the new layer over and down until you get what you like.  To merge the two Type layers, turn the Background Layer's Visibility off and do a Merge Visible.  Touch up the edges of the logo a little if necessary.  Then turn the Background Layer's visibility back on; you should see something that looks like this:

(Of course, if you already have a Thump Photography logo, just move it into the image, size it, and center it.  But it won't be as nice as this.)

Now here comes The Invisible Man part.  Click somewhere on the logo with the Magic Wand tool to select it all.  (You may need to press Select --> Similar if not all of the logo is selected.)  Now press Edit --> Fill, select 50% Gray for the Contents, press OK, and then press Ctrl-D to deselect the logo.  Here's what it should look like:

"But that's not invisible!" I can hear you shout.  You're right, but that's because the Blend Mode is still set to Normal.  Just set it to Overlay and this is what you get:

See?  All gone.  And now for the fog.  Set the Blend Mode back to Normal, and add a Bevel and Emboss Style to the Logo Layer, using parameters like these:

Now you should see a not-invisible something that looks like this:

Adjust the Depth and Size parameters to suit your tastes, and then set the Blend Mode to Overlay again.  And now -- nothing but fog!

"Well, that doesn't look so hot," you mutter.  "And besides, how do I use it?" 

(Complaints, complaints, that's all I ever get.)  Okay, proceed as follows.  First, delete the Background Layer.  Then save the file as a PSD, using a name like "MyWatermark.psd" in a special folder.  Now open an image, any image, go ahead, surprise me.  As soon as the image is open, go to  the File Menu and click on "Place..."  When the selection dialog opens, navigate to your special folder and select "MyWatermark.psd."  After a moment you'll see something like this:

Observe that the File --> Place command has calculated where the center and edges of your image are, and made sure that the center and edges of the file to be Placed are properly adjusted to fit perfectly.  All you have to do is press the Commit checkmark and reset the Blend Mode to Overlay, with this result:

As you can see, your logo is invisible but the fog shows where it is.  It's clearly Thump Photography.

Final thoughts:

1. Some people have argued that you could throw flour over The Invisible Man to make him visible.  This argument overlooks the fact that anything that touches The Invisible Man (like his clothes, or a coating of flour) inherits the same properties that he has, namely, the ability to allow light to pass through without attenuation.  No, fog is the answer.
    

2. Centering and sizing the logo automatically is done by the File --> Place command, which has many other uses.  The Invisible Man technique is independent of that, and can also be used for many other things, such as

3. A batch action can easily be written so that your logo can be attached to a whole folder full of images.  Contact the Webmaster with your request for help with this action.

(P.S.: Madison, Olivia, and Bows furnished courtesy of Grandma Linda.)