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Properties of Trap

General Settings

  • Enable Trapping

    • Retrap Trapped Pages
      • Will retrap pages previously trapped by Access. Will not delete traps created in upstream software.
    • Trap Time-Out __ seconds  Default 0 seconds.
      • Overly complex files can sometimes take a very long time to trap. You can set a time-out for very complex files so they don't cause a bottle in production. The file can potentially be trapped at a later time when there is less production pressure.
    • Trap Tiling Pattern
      • Traps internal objects in tiling patterns. Tiling patterns can create two much complexity and slow-down or hang trapping, so option can be turned off.

Size

  • Width / Height (inch / cm / mm / pts)

    • Specify values and chose a unit of Measure

  • Line Splits

    • Controls the size of traps that extend into stroked objects.

    • Stroke widths of up to x% of the trap width specified will get an inside trap with half the stroke width.

    • This avoids a third color in the stroke center that is a different color than the trap colors.

    • Range 0% to 10,000.0%

      Example
      Default line split = 200.0%
      Stroke width = 0.4 pt
      Trap width = 0.25 pt
      Result = Inside trap width of 0.2 pt

    • In this example, trap width multiplied by line split value is greater than the stroke width divided by the two inside traps, (0.25 × 2)  (0.42), so inside traps are forced to shrink to half the stroke width, or 0.2 pt.

    • If the line split is more than 200.0%, and the trap width is greater than the stroke width divided by two, then the trap width is forced to half of the stroke width.

    • If the line split is 0.0%, the feature is disabled and there is no change to the trap width; trapping into the stroke is like trapping into any other object.

Geometry

  • Line Joins
    • Determines the shape of the join between two trap segments.
      Options:
      • Bevel
      • Round
      • Miter

  • Miter Limit
    • Determines the angle at which an acute-angle mitered join will create a mitrer or be clipped off to prevent excessively long pointed joints.
  • 3 Color Joins
    • Determines the shape of a trap where three or more objects meet.
      Options:
      • Mitered Corners
      • Clipped Chokes

  • Trap Trimming
    • Reduces the width and shape of traps extending into very thin color areas. This often results in traps of variable widths.
    • When a regular trap width may allow the trap stroke to get too close to an object edge, the trapped is reduced (trimmed) to be only half the width of the color area being trapped into.
      Options:
      • None
      • Automatic

Create Cutbacks

Will reduce the trap widths of lighter inks in a multi-ink color (such as a Rich Black) that borders on a white area. This prevents lighter colors from "peeking out" at the edges of Rich Black objects if there is misregistration.

  • Create Cutbacks when Primary tint value is above
    The Primary tint is the darkest ink in an ink color combination, determined by neutral ink densities. For a Rich Black made up of Black 100%, Cyan 40%, the primary tint is Black, so the cyan will be pulled back along object edges.
  • Create Cutbacks when Primary Ink Neutral Density is above
    Determines the minimum Primary Ink density required to create Cutbacks.
  • Cutbacks width percentage of global trap width
    Allows you to specify cutbacks that are smaller than the specified trap width. 

Images

Controls whether images trap to objects and/or images trap to other images

  • Trap to 
    • Objects
      Select this to trap raster images to vector objects
    • Images
      Select this to trap images to other images. 
  • Direction
    Determines placement of traps based on either object colors or object types. 
    You can select one of the following options:
    • Automatic
      Lighter trapping colors will be expanded into darker colors, based on their neutral print densities.
    • Center
      The trap will be equally expanded into both colors from the border between the colors, regardless of their neutral densities.
    • Into Image
      A vector object will always expand into raster image objects 
    • Into Object
      An image object will always expand into a vector object
  • 1-bit images
    Determines how 1-bit images or masked raster objects are trapped. Because 1-bit images are typically high resolution (800 – 2400 dpi), they can take an excessively long time to be analyzed and trapped (hours+).
    • Trap All
      Traps all colorized 1-bit images with vector traps, no matter how complex the image. 
    • Ignore Complex
      Will trap some images but ignore others, based on an estimate of how long it would take to create vector traps for a specific bitmap.
    • Ignore All
      Will not trap any 1-bit images.

Black

These settings determine how Black and Rich Black (process color mix containing Black and varying amounts of Cyan, Magenta and Yellow) are Trap. You an set other colors to Trap using Black Trap settings when defining Colorant properties in a Color Library.

  • Black Width Scaling
    • Calculates black trap width as a percentage of global Trap Width value. The additional margin ensures any additional colorants in a rich black don't peek out from under the black.
    • A 100% setting pulls back an object's color separations (except for black) the same distance as the global trap width used on the rest of the page. Traps to black objects are the same size as other traps.
    • A less than 100% setting produces narrower traps. For example, a 50% scale means that traps to black objects will be 50% smaller than the usual trap width.
    • A greater than 100% setting produces wider traps. For example, a 200% scale means that traps to black objects will be twice the size of the usual trap width.
    • Range: 1% to 1000%
    • Default: 100%

  • Black Color Limit
    • Determines the minimum screen percentage at which the trapping engine considers black to be 100%, and therefore applies black trapping rules.


    • Black trapping rules include:

      • Traps to objects defined as black are affected by Black Width Scaling.

      • Colors placed underneath overprinting black solid objects form rich blacks. In areas where a rich black borders an unpainted object such as the substrate, the color under black will be kept back from the border.

      • The rules above do not apply unless the tint of the black objects is greater than or equal to the Black Color Limit.

    • A setting of 0 means that all screen percentages of the color black are considered black. A setting of 100 means that only solid black is considered black.

    • Range: 1% to 100%

    • Default: 95%

  • Black Density Limit
    • Determines the neutral density value at which the trap engine considers an ink to be black, and therefore applies black trapping rules.
    • Any ink set to a density higher than black causes the black to be treated as the lighter color. The black spreads into the higher density color. You may want to set a metallic ink density higher than black so that it traps correctly.
    • A setting of 10.0 means that no ink is considered black.
    • Range: 0.00 to 10.0
    • Default: 1.6

  • Overprint Black Strokes Up To  __  (inch / cm / mm / pts)
    • Sets all black strokes with a width of up to <n.n> pt to overprint instead of trapping them. This overprint also applies to all strokes colored with spot colors whose neutral density is higher than the Black Density Limit.
    • Select this check box to enable this feature, and then specify a stroke width or accept the default. Clear the check box to disable this feature.
    • Range: 1 to 100 points

  • Overprint Black Graphics
    • Sets all black vector graphics to overprint instead of trapping them. This overprint also applies to vector graphics colored with spot colors whose neutral density is higher than the Black Density Limit.
    • Select the Overprint Black Graphic check box to enable this feature; clear the check box to disable this feature.

  • Overprint Black Bitmap
    • Sets all black bitmap graphics to overprint instead of trapping them. This overprint also applies to bitmap graphics colored with spot colors whose neutral density is higher than the Black Density Limit.
    • Select the Overprint Black Bitmaps check box to enable this feature; clear the check box to disable this feature.

Trap

  • Step Limit
    • Determines whether a trap will be generated between adjacent colors (objects) depending on the relative difference (in %) in their amounts of colorants (inks). If the relative difference in amounts of colorants between two objects is less than the relative step limit specified, then no traps are generated.
    • A setting of 0 removes Step Limit as a criteria for trapping. A setting of 100 disables trapping.
    • Range: 0 to 100%
    • There is also an absolute threshold of 5% to prevent traps between very light colors. See Minimum Absolute Step Limit.

  • Minimum Absolute Step Limit
    • Determines that no traps will be generated between adjacent colors (objects) if the absolute difference in the amount of colorants between two objects is less than the absolute step limit.
    • This limit is intended to prevent traps between very light colors or colors with very small color steps as found in blends. For a trap to occur, the difference between amounts of colorants (separations) must be greater than this Minimum Absolute Step Limit and the value set for the relative step limit.
    • Range: 1% to 100%
    • Default: 5.0%

  • Common Density Limit
    • Determines whether a trap will be generated between adjacent objects that have common colors. If the two objects have enough common color, a trap is not required.
    • If a color is to be trapped based on the Step Limit value, the neutral density of the shared color is calculated and compared to the Common Density Limit value. If the shared neutral density is greater than the limit, no trapping occurs.
    • A setting of 3.294 is approximately equivalent to the sum of 100% of each of the CMYK inks. A trap is always created if you type a value greater than or equal to 3.294.
    • Range: 0.001 to 10.0
    • Default: 0.5

  • Centerline Trap Limit
    • Determines whether centerline traps are created between objects with similar values for neutral density. The system compares the neutral densities of two adjacent colors and creates a centerline trap when the neutral density of the lighter area is greater than the neutral
    • density of the darker area multiplied by the Centerline Trap Limit value.
    • Note: You cannot add a centerline trap between black or opaque inks.
    • A setting of 0 results in almost all centerline traps. A setting of 100 results in no centerline traps unless adjacent objects have exactly the same value for neutral density.
    • Range: 1% to 100%
    • Default: 100%

  • Trap Color Scaling
    • Lightens the intensity of the trap color for a particular separation.
    • Trap color scaling helps to make traps in sensitive trapping situations less noticeable, for example, when trapping pastels. Scaling reduces the visibility of traps by reducing the amount of each component ink relative to its contribution to the trap color.
    • The system applies the Trap Color Scaling value to the separation values of the trap that originates from the lighter color (when neutral densities are compared).
    • A setting of 0 makes the traps invisible because all separations of the trap color become equal to the darker color. A setting of 100 switches off Trap Color Scaling.
    • Range: 0 to 100%

  • Ignore Overprint Density Limit
    • Traps will not be created for overprinting objects when their Neutral Density is above X. X is a decimal value with 3 digits with a range of 0-10.
    • A value of 0 means to ignore all overprints and a value of 10 means to ignore no overprints. The default value of 10 is set to match the legacy behavior when this feature did not exist.

  • Keepaway Mode
    • Applies an opaque white trap to eligible color intersections. An eligible color intersection is one that is between adjacent objects painted by different inks. That is, each object is painted by at least one ink that does not paint the other.
    • A keepaway trap is also called a knockout trap or a reverse trap.
    • Keepaway mode is used in packaging (metal decorating).

Text

  • Overprint Black Text Limit
    • Overprints black text with a point size less than or equal to this value.


    • A setting of 0 points causes all text to be treated the same as other objects. A setting of 100 causes all text sized less than or equal to 100 points to be overprinted rather than trapped.

    • You may want to choose a point size equal to your body text to make headlines trap normally and body text overprint.

    • Range: 0 to 1000 pt

    • Default: 12 pt

    • Note: This setting also affects Rich Black text.

  • Small Text Size Limit
    • Determines at what point size text traps should be scaled. The scale percentage is set in the Small Text Width Scaling (%) box.
    • Note: Overprint cannot be used with colored text because overprinting changes the color of the text. For small colored text, you may want to set a smaller trap size.
    • A setting of 0 means that no text traps are scaled. A setting of 100 means that traps are scaled for all text sized less than or equal to 100 points. Scaling traps for text that is 6 points or smaller (the default value) can significantly improve readability.
    • Range: 0 to 100 pt
    • Default: 6 pt

  • Small Text Width Scaling
    • Calculates the width of a small text trap as a percentage of the Trap Width value. Scaled traps are applied to text objects based on the value of Small Text Size Limit.
    • Range: 0 to 1000%
    • Default: 75%

  • Text Grouping
    • Groups text objects when trapping. All of the characters in a group will have the same trap direction and color.

    • Choose from the following grouping options—none, characters, words (default), lines.

    • Grouping by units larger than characters—such as words and lines—speeds up trapping and can sometimes give better visual results. Grouping by characters gives the most flexibility since each character can then have a different trap direction and color, depending on its background. A setting of none will keep the text groupings that are set up when the file is converted to PDF.

    • Note: This option is available only if the Trapper JTP is selected in the JTP box.

Color Settings

  • Trap Settings Lookup
    • Trap settings rely on Colorant Properties as defined for a color in a Color Library, including Neutral Density, Overprint and Knockout Handling and Trapping parameters. See Color Libraries under Resources / Color Controls / Color Libraries for more information.
    • There are two libraries visible in Trap Configuration: 
      • Selectable Libraries: a list of all Color Libraries that have been imported into your Access system.
      • Selected Libraries: these are the libraries that will actually be used by a specific Trap Process.
  • Print Sequence
    • Colors will be trapped based on the Print Sequence Position number as set in the Print Sequence panel. The Print Sequence must agree with the actual ink laydown order on your press.
    • Select an Artwork Color and use the Up and Down arrows to change the Print Sequence Position.
    • You can add additional Artwork Colors to the Print Sequence by pressing the + button. A list of colors will be presented from the Selected Libraries.
  • Trap by Neutral Density
    • Current limitation is that a Color Library containing Neutral Density definitions for Cyan, Magenta, Yellow and Black must be in the list of Selected Libraries, or trapping will fail.
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