Photoshop Transparencys
Photoshop Transparencys
You may have struck this problem at some time - you want to include
a photo of something in your layout but need to remove the background.
Not such a big deal, you just open Photoshop or PhotoPaint and trace
around the object then white out the background before placing it
into your layout. This will be fine if the area of your job that you
place the picture in is white, but what if you have to place it over
an area of colour, or over other objects?
The solution is to deep etch the photo with a clipping path, which is a curve definition included with the photo scan that defines an area that will remain transparent when printed on a Postscript printer. A lot of people want to do this, but run into trouble, so here are some guidelines on how to do it using Photoshop.
There are two ways to define the area that the clipping path will
be applied to.
The first way is to use the Selection Tools, probably the Magic Wand and Lasso Tools to create a selection. This method is often quicker if the object is easy to visually separate from the background due to colour differences or well defined edges.
The second way is by tracing around the area using the Pen Tools to create a closed path that defines the area to keep. Open the Paths Palette and create a new path then draw a path around the area. The key to doing this properly is to minimise the number of node points and use long straight and curved path segments to define the area, not lots of little straight segments that approximate the curves.
If you make your selection path too complicated by putting in lots of straight nodes, you will have problems printing the final image on an imagesetter as the path will become too complex to image. Use the absolute minimum number of nodes!
If you chose the first method of defining your area, the selection must first be converted to a path using the Make Path command from the paths palette control menu. Choose a tolerance value that is fairly high (say 5-10 pixels) to make sure that you don't end up with a path that is too complex to image. Use the pen+, pen- and convert direction point tools (from the paths palette) to delete unnecessary nodes from the path and adjust any curve shapes that don't quite fit
Each time you select a point with the convert direction tool
it toggles between being a corner point and a smooth point.
Once you are happy with the path, give it a name and save it using the paths palette.
If you chose the second method of defining your area you already have a path, make sure it is the current path (the one that is white in the paths menu if you have more than one path).
To make the current path the clipping path simply choose Clipping Path from the palette control menu.
Notice that we haven't actually whited out the background of the image. In fact it isn't necessary to do this as the clipping path defines the area that will be transparent on the final output, but you might find it satisfying to see the background disappear now.
To do this convert the path to a selection, invert it using Invert Selection from the Select menu and fill the resulting area with white using the Fill command from the Edit menu.
The final step is to save the file as an EPS with clipping path. Use the Save As command from the file menu and select EPS. In the dialog box that results make sure that the path name you previously made a clipping path is shown as the clipping path for this EPS file. Using the dropdown menu, set the flatness value to 8, and don't mess with any other settings.
The resulting EPS file may now be used with CorelDRAW!, Pagemaker or Quark to produce the effect you were after. Remember that the clipping path can only be used with EPS files, and will only work properly when you print to a Postscript printer.
