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Bitmaps
USING PATHS
 
This page refers to Adobe Photoshop but similar options are now available in other painting programs. A path is an editable line or curve you draw using the Paths pen tool - the tool uses some of the Adobe Illustrator Bezier Curve software engine. Bezier curves are lines that can be easily reshaped, whether they are set to straight line segments or curved segments.

path being created around pups heads

The path Pen Tool lets you draw smooth-edged paths with precision where the normal Selection Tools may be too difficult to use, and paths are useful for defining areas to fill, and drawing shapes that can be stroked using one of the programs painting tools and settings.

Paths can be useful for long-term storage of many masks saved with a Photoshop generic file type, because saved paths take up much less disk space than a saved selection - which is actually a greyscale and equivalent to one picture channel - in bytes. Paths can be resized or scaled without losing any accuracy and you can copy paths from one image to another like selections, plus they can be copied / exported and pasted / placed to and from Adobe Illustrator files.

Prior to version 4 of Photoshop the paths tools are accessed via the paths palette and in version 4+ they have been placed in the floating Tool Box.

Straight line segments can be readily converted to curved segments, and vice versa.

Any selection area created with a Photoshop Selection Tool can be converted to a path and a path can be converted to a selection.

Note: Using the Make Path command eliminates any feathering applied to the selection plus the Make Path command may alter the shape of the selection, depending on the complexity of the path and the tolerance value you choose in the Make Path dialog box. Every node added to a path adds to the paths complexity and very large complex paths can cause problems when output if saved as an .EPS file and included in another program. i.e the following:

Greatest advantage

The greatest advantage when using paths is in the ability to save one path as a Clipping path. Then when the image file is saved as an .EPS file the shape of that one path is used to contour part of the picture area. The exported image will have a transparent back ground when placed in another appropriate program - i.e. a Pagelayout program.

Step 1. Create your path(s).
Step 2. Select and Save each path that you want to keep for later use.
Step 3. Select the path used for contouring and Save As Clipping Path.
Step 4. Save the file as an .EPS file type and use a Preview header for Win software. The Clipping path must be nominated in the option window.
Step 5. Place the image file into Quark Xpress etc.
Note: Saving paths and Clipping Paths is performed via the Paths Palette drop down menu.

 No ContouringPath Contoured image

Above left shows how a bitmapped image will appear normally when placed over another object in a Pagelayout or Drawing program. The image on the right displays the result using a Clipping path and the .EPS file format for the bitmap image.

Note: An imported clipped .EPS might appear on the page of your layout program with a coloured background when using Windows software. A test print will show that the clipping path works and it is just the display that is at fault. Adobe do not seem to want fix this filter problem that has been around for some time so you just have to ignore the background while working on the job.

Many will argue that I am talking through my hat, but this, and saving Duotones, are probably the only times that a bitmap image type (pixels) should be saved in .EPS format. I will discuss the reasons why in the 'Page & Image Errors' topic via the TEXT & DRAWING Lab.

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e-mail 1997 '98. Last Revised:  Friday, 31 October 2003 22:04