Floating Pictures on Shadows

One of the nice things about graphics programs like Adobe Photoshop and The GIMP, is that you can do many cool things with images, text, and textures. If you don't already have the added plug-ins that have been contributed to the GIMP, you should get them. They are available (in some cases, precompiled) at The GIMP Plug-In List.

This is a tutorial on how to get a shadow effect under a picture. The concept is fairly simple. I highly recommend looking at the Using Channel Ops with GIMP page that Zachary Beane has.

If you have, instead of a photo, a logo or something that is uniformly made of dark colors, you might see if this tutorial will work. The tutorial on this page is only for images which have light-colored or white sections (like most any photograph will).

Ok, so you have a picture and you would like to get a shadow under it. First thing to do is take the picture and, if it does not have a white border, add one. You can do this my simple copying and pasting into a larger Window (Ctrl+C to copy, Ctrl+V to paste), or you can use the Filters->Channel Ops->Canvas-Size filter. Add a good amount of border space, you can always trim it later.

Untitled-1.0.jpg Figure 1: Our picture with a white border.

Now you are going Duplicate (Alt+D) the picture and make the area it is in black. There are a few techniques I've been able use to get this black mask. I'm not particularly happy with any of them, but they do mostly work.

First method:
Take the appropriate Selection tool, select only the picture (not even one pixel too far in or out!) and then use the Bucket Fill to paint it black. This is simple if you have a rectangular or circler picture (use the Rect or Ellipse selection tools). If your image is complex, with many sides, you will probably need to us the brush to fill in areas.
Second method:
Take the Fuzzy Select tool and click anywhere on the white border. You should get an outline of the entire border around your picture. Now hit Ctrl+C to copy it into your buffer. Now Hit Ctrl+A to select the entire piece, and Bucket Fill it black. Finally, hit Ctrl+V to paste the white border back in. This sounds a bit easier then the former, but I've found I have to do touch up work with the brush afterwords.
Third method:
Take the Gamma Correction (Alt+G) filter and lower them all down to 0.1. This should make most of your picture black. You can fill in the rest with a brush.

Untitled-2.0.jpg Figure 2: Our black mask of the picture.

Now, Offset (Alt+O) this mask. The higher or lower X and Y numbers you specify will make for more or less shadow. I usually use 3X and 4Y for smaller pictures, and 9X+12Y for larger ones. Take this offset image and Gaussian Blur (Shift+Alt+B) it at anywhere from 5 to 10, depending on how big it is. This is our shadow image.

Untitled-3.0.jpg Figure 3: Our offset image.

Untitled-3.1.jpg Figure 3.1: Our shadow (Figure 3 blurred).

Now we make a Composite (Alt+C). The First Image is our original picture (Figure 1), our Second Image is the shadow (Figure 3.1), and the Mask Image is our black mask (Figure 2). As Xach pointed out in the Using Channel Ops with GIMP page, the composite does the following:

Final Result: Untitled-4.0.jpg
James A. Robinson <jimr@simons-rock.edu>
Last modified: Mon Jul 22 23:37:19 EDT 1996