fixing overprints - puzzleflow

Fixing Overprints -

Reprinted from the PuzzleFlow Blog

The desire to preserve or remove overprints (black and otherwise) depends on the type of printing your are doing – the type of product your are creating. Is it a high-end art piece, a direct mail fl ier on glossy stock off a sheet-fed press, or an advertisement in a newspaper? In each case, depending on con-tent, method and fi nal use, the way overprints are treated may be different. Design, too, may play a part in the need to preserve overprints.

At PuzzleFlow, our focus is on prepress, prefl ighting, and auto-correcting fi les to prepare them for proper printing, so I won’t be going into great detail about design. Suffi ce it to say that the design of a piece can often make it harder to print. Whether that is due to the fact that the piece is being re-purposed and distributed using different methods (sheet-fed, web press, digital press, internet, etc.), or perhaps the designer doesn’t know the production method or hasn’t been given the time to properly prepare the piece for the chosen production method; whatever the reason, overprint settings can, and often do, create problems for fi nal production.

Any decent PDF based system can be set up to deal with overprints and, in the vast majority of cases, automatically correct them. I say any decent PDF based system as if there are many, but in real-ity there are only a handful of powerful PDF libraries (what PDF compatible systems use to work with PDF fi les) out there. At PuzzleFlow, we have our own PDF library which, as of this writing, has been in development and kept in continual update for about 12 years. Needless to say, PuzzleFlow systems can easily help you by automating how overprints are handled and corrected to suit your specifi c needs.

The concepts from here on out are universal to PDF over-print processing and correction, but the tools I will be dis-cussing and the settings used will be from the PuzzleFlow Automator/WebPairer solution interface – a workfl ow that is specialized to organize, manage and automate newspaper and web-printing workfl ow. Therefore, the rest of this article will be useful to all, but is specifi c to Automator and WebPairer users.

The page shown to the right has been created to illustrate a number of overprinting issues like:

knock-out “white” type set to overprint

a black box placed over part of a picture

black type over a colored box

“rich/4-color” RGB black type

two colored objects overlapping with one set to overprint

an object (in this case a square) set to “registration” color

All these are common problems related to black, or other colors (including white), being set to overprint each other.

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Fixing Overprints

Fixing Overprints -

When viewed in Adobe Acrobat – using some very generic viewing settings, the page looks fi ne, as far as it goes. One can identify a problem, that RGB color is used, by looking at the Separations list in the Output Preview window, but visually things look good.

However, some changes in the Acrobat Output Preview settings will show some more problems.

For instance, turning on “Simulate Overprinting” in the Acrobat Output Preview window reveals that:

the white overprint text disappears

the black box is overprinting the bottom of the photograph

the yellow box is set to overprint the cyan box

Original PDF page viewed in Adobe Acrobat

Acrobat Output Preview settings used to view page



Fixing Overprints -

At this point, using Acrobat, we have been able to identify some of the problems on this page, but our goal is not to identify possible printing problems, our goal is not to have printing problems at all.

Someone without a PuzzleFlow system (or similar automated PDF tools) would be forced to either print the page as it is, try and locate the original documents and fi x the problems, or go back to the customer who supplied the fi le and ask them to fi x it. Someone with PuzzleFlow Automator, WebPairer (and other PuzzleFlow Solutions) has automated prefl ight tools to identify the problems and the automatic “Pre-press Fixes” to correct the problems without any user intervention being required.

The PuzzleFlow Prepress Fixes can do automatic correction for many common fi le preparation prob-lems; things like “hairlines,” fragmented images, embedded profi les, font issues and more. But for now, I will focus only on items related to overprinting and knockout problems. The various settings to control the overprint correction can be found in Settings/Queue Preferences/Prepress Fixes.

The settings we are interested in are:

As stated before, many of these settings are similar in other PDF prefl ight and correction software. The set-tings shown above are examples set in PuzzleFlow Automator and WebPairer.

When the same sample fi le as before is put through the system using the above settings, the results look like the example shown here.

The “Knock-Out Type” set to white overprint is clearly fi xed. Other things have been fi xed too, but you can’t be sure using these Acrobat Output Preview settings.

By looking closely at the Out-put preview, you can also tell that the “rich” or “4-color” black type (caused by it originally being RGB type) has been fi xed. Note that the RGB color does not appear in the colors list.

Acrobat Output Preview

settings used to view page Original PDF page viewed in Adobe Acrobat

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Fixing Overprints -

Now, by changing the settings in the Acrobat Output Preview, we will be able to identify how differ-ent overprint settings in PuzzleFlow can affect the items on the page.

In the example on the right, we are looking at the same page, pro-cessed with the same “rules” but, by turning off the Process Black separation in the preview settings, we can more easily see what has been fi xed and what has not:

knock-out “white” type set to overprint (FIXED)

a black box placed over part of a picture (NOT FIXED)

black type over a colored box (NOT FIXED) depending on your requirements*

“rich/4-color” RGB black type (FIXED)

two colored objects overlapping with one set to overprint (NOT FIXED) depending our your requirements**

an object (in this case a square) set to “registration” color (NOT FIXED)

*Regarding black type overprinting a picture or a colored area - you may or may not want this to happen. For that matter, you may even want small type to overprint (making sure registration problems are not an issue) and larger type to knock-out. For purposes of our example, we are going to set the fi xing rules to do just that - knock-out the large type, overprint the small type.

**Regarding the colored objects overlapping - again this may be desired, depending on the design of the page/object in question. The only way to know is by looking at the soft- and/or hard-proof of the page and decide for yourself what the right behavior is. With PuzzleFlow, you can then set the fi xing rules for one queue/workfl ow to keep the objects overprinting and another to remove them (you can even set these differently on a publication by publication basis) - allowing you to easily process the fi le both ways. What those settings are will be come clear in the next pages.

Clearly the above results are not ideal. In the following pages we will see how changes in the Prepress Fixes settings can auto-correct all of the problems on the example page.



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Fixing Overprints -

A Closer Look At the PuzzleFlow WebPairer/Automator Overprint and Rich Black Settings

By changing some of the settings in the PuzzleFlow interface, Settings/Queue Preferences/Prepress Fixes, we can change the outcome of the automatic prepress fi xes:

You will note as we go through the settings, that the “fi x” behavior is different depending on the word-ing of the settings. For instance “Remove Rich Black / Fix 4-color black” for objects “under” a specifi c point size will do just that - fi x only objects smaller than the specifi ed size. Also, if the check box is not checked, the action will not be taken. For instance, if you always want to keep rich black “fi lls” then turn off the check box.

Another thing worth noting is that all of the overprint settings we will be looking at refer to “items” or “vector objects” like: strokes, fi lls and text. The overprint behavior and the composition of color builds in an “image” like a placed JPEG or TIFF fi le, can not and will not be altered by these settings. The relationship and behavior of a vector object with regard to an image object can and will be addressed but no system can look within an image object to determine the nature and intent of specifi c graphic objects within it. Therefore, for instance, 4-color black text that has been “fl attened” into an image fi le can not be corrected automatically by any PDF correction system.

Remove Rich Black Auto-fi xing behavior with the settings shown:

converts rich/4-color black to 100% process black for fi lled vector objects with a dimension smaller than 1200 points (~16.5 inches) in any direction

converts rich/4-color black to 100% process black for stroked vector objects with a width smaller than 10 points

converts rich/4-color black to 100% process black for text under 200 points

Note: the higher you set these values the MORE objects will be “corrected.”

Although the example settings above did just fi ne at fi xing rich black type on our example page. Here is a tip: by setting the “Remove Rich

Black . . .” settings to high numbers, you will further insure that all RGB/ 4-color/rich black items are converted to process black only.

Overprint Black Auto-fi xing behavior with the settings shown:

objects (like boxes and circles and frames) with BLACK fi lls that are less than 144 points (2 inches) in either direction will overprint anything under them

strokes that are set to black and are under 4 points in width with over-print anything under them

type that is smaller than 100 point and that is black will overprint any-thing under it

Fixing Overprints -

It is important to note that the Black Overprint settings will change the behavior of black objects and text - even if it isn’t set to overprint in the incoming fi le. Therefore the above settings will “force” fi lls that are 2 inches (144 points) or smaller overprint everything under them, and “force” strokes under 4 points to overprint, and “force” all type under 100 points to overprint.

On our example page - the type over color - both the large and small type, will be “forced” to overprint the green box below them with the settings shown above.

Normally this is not a problem, the overprinted type will look darker - and that isn’t so bad. But if the type is not entirely over the colored box, then there may be a problem.

If the type looked like the example to the left - only a portion of the type over the color, and it was forced to overprint the color - when printed on press, the bottom half of the type would look darker than the top half of the type. Not normally a desired effect.

Quite often, printers will not want larger type to overprint and will want smaller type to overprint. Some reasons for wanting smaller type to overprint are that registration issues are exaggerated with the smaller type (at least visually) - that is, it is easier to see when “knock-out” small type is out of register; if trap-ping is used, the trapping itself can make small type look quite strange; in newsprint, there is less ink for small type and less natural gain from the small type that would help hide any misregistration; and the chances of having small type “overhang” a color area in a design is quite small. That is the short list, and the long way of saying, you may want to force small type to overprint.

Overprint Black Auto-fi xing behavior with the settings shown:

objects with BLACK fi lls that are less than 72 points (1 inch) in either direction will overprint anything under them

unchanged from above example

type that is smaller than 13 point and that is black willoverprint anything under it - only small type overprints

Black type behavior with above overprint settings and showing Black Separation

Black type behavior with above overprint settings and NOT showing Black Separation

Fixing Overprints -

Remove Overprint Auto-fi xing behavior with the settings shown:

objects (like boxes and circles and frames) with BLACK fi lls that are larger than 144 points (2 inches) in either direction will NOT overprint anything (if overprint is set in the original fi le, it will be removed)

strokes that are set to black and are over 4 points in width will NOT over-print anything (if overprint is set in the original fi le, it will be removed)

type that is larger than 14 point and that is black will NOT overprint anything (if overprint is set in the original fi le, it will be removed)

if you check this box on, any pre-confi gured/pre-set overprints for any and all objects and colors will be “stripped” or removed. Also, if this is checked on, the “Remove Black Overprint” options will disappear - be-cause all black overprint will be removed when this is checked. Also, see the important note below

in WebPairer and Automator, this option is ALWAYS ON, and should be. It is shown in the interface as an informational item - to let you know it is always on

Here is an important thing to note: When you remove any black overprint in WebPairer/Automator using either the “Remove Black Overprint” settings or the “Remove ALL overprint” setting, the “Overprint Black” settings will STILL APPLY. All specifi ed overprints set in the original fi le are removed FIRST and the “Overprint Black” settings are applied AFTER that.

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So if you don’t want to put any overprint back in, make sure the Overprint Black settings are properly set to prevent such an occurrence.

Also important to note is that WebPairer and Automator make sure that all of this correction of black overprints is done AFTER any incorrectly defi ned blacks (RGB black, 4-color black, rick black, etc.)have been corrected. That way, everything is properly set to 100% black (K) before the “true” black overprinting is analyzed and the called for fi xes are applied.

Fixing Overprints -

To wrap things up, these fi nal examples show what will happen with Remove ALL overprints turned on, with the rich / 4-color black fi xed and with small black type being set to overprint.

The top sample shows the page in Adobe Acrobat with all the fi xes applied and with all of the colors visible. The bottom sample shows the same page

with black turned off in the preview to illustrate how the fi xes were applied.

The black fi eld with “Knock-Out Type” on it no longer overprints the bottom of the picture - the picture has been clipped.

The large type knocks out of the green, but the small type does not.

The rich / 4-color black is fi xed and is K only.

The black box made from “registration” color (100, 100, 100, 100) has been changed to K only.

The overprint setting for the yellow box has been removed and it no longer overprints the cyan box. Note: the overprint behavior of colored boxes may be a design element and may actually be cor-rect, we are using this as an example to illustrate the behavior of the “Remove ALL overprint” set-

ting. Use this setting carefully.

And best of all, with Automator & WebPairer . . . these overprint “fi xes” are all performed auto-matically when the fi le arrives in the system, are visible in a soft proof, can be confi gured differ-ently for each workfl ow - even each publication, can be overrid-den or applied based on different hotfolders, and will make your publication much easier to print.

fixing overprints - puzzleflow

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