The Actions, perfected over several days of testing on both Mac OS and Windows, allows this process to be completed in seconds – and all within Illustrator.
Whilst covering drop shadows and glows in the previous object-specific flexo ink drop-off article, the matter of producing accurate cut-off levels for mixed value process CMYK shadows and glows was mentioned. The problem with generating these was due to the way in which drop shadows and glows are created internally within Illustrator (refer to details).
The best practice prescribed imposed significant limits on the shadow and glow colors possible as each ink had to be defined at 100% tint.
This article provides an Illustrator Action set that uses a clever combination of Illustrator and Phantasm CS Studio and Publisher tools. These automatically generate a cut-off drop shadow or glow based on any process CMYK color, applied to any embedded object type. The Actions, perfected over several days of testing on both Mac OS and Windows, allows this process to be completed in seconds – and all within Illustrator – as opposed to a significantly longer period if produced manually in a combination of Illustrator and Photoshop.
Note: This technique is not compatible with Illustrator CS2 or below due to a lack of Device-N (multi-ink) image support which was introduced in Illustrator CS3.
Overview of the process
As a the standard Illustrator shadow and glow live Effects defined with a mixed level CMYK color can not have an accurate cut-off level applied to each channel, an Illustrator Action set has been produced (shown, left) that modifies the shadow component and applies a pre-determined cut-off correctly. Even though the shadow or glow is therefore no longer “live” or linked to the original artwork, the Action process means that re-applying the glow takes a matter of seconds.
The Actions rely on the presence of two Graphic Styles within the Illustrator document. These are added with two clicks through the use of the Graphic Style library system within Illustrator and their availability in a persistent panel (a Graphic Style library panel that optionally re-appears in every Illustrator session). This technique was devised in an earlier article Adding Effects to Illustrator Actions.
Any operator familiar with Illustrator can easily use this process as the standard Drop Shadow and Inner/Outer Glow windows are still used to define the shadow or glow characteristics.
Video demonstration
A written step-by-step guide is provided next. However, for a quick preview of the steps necessary, the following video has been provided:
If you have problems viewing this movie, you can view the movie on the Astute Graphics YouTube channel or click on the movie file link: www.astutegraphics.com/movies/blog/flexo-process-shadow-cut-off.mov
Step-by-step guide
One-off task of adding Actions and Graphic Styles
Before you can use the Action sets to produce cut-off curves on drop shadows and glows, it’s first necessary to add the associated Actions and Graphic Styles to Illustrator. This is a one-off task and they will be automatically available for future sessions.
Firstly, download the Actions set and Graphic Styles:
ZIP archive containing Actions for both Illustrator CS3 and CS4, plus a slightly modified copy for Illustrator CS5 (6Kb)Quit Illustrator, if running and then copy these files into their respective folders within:
- Mac OS:
- Windows:
Restart Illustrator and ensure the and panels are both visible (if not, they can be found in the menu).
With the Actions panel, click on the pull-down menu (shown above) and select and locate the Actions file. the Action set containing 5 variants of the “Process shadow” cut-off Actions should now be present and will re-appear automatically in the next Illustrator session.
With the Graphic Styles panel, click on the pull-down menu and select . This will open a new panel containing two Graphic Styles which are required for the Action to work. In the new panel, click on the pull-down menu and tick which ensures that this Graphic Styles panel will appear in every Illustrator session until closed or the persistent option is toggled off once more.
These steps should not need to be repeated. However, if the Actions or associated Graphic Styles were to disappear in the future, they are always accessible in the Illustrator Presets folder.
Create a drop shadow with flexo cut-off
You are now ready to produce a drop shadow using the Action.
Open or create a CMYK document. Without any objects selected, click on both Graphic Styles that appear in the panel to import them into your document’s Graphic Styles panel. (This process needs to be done once for each document you wish to run the flexo shadow/glow cut-off Action).
Select a single embedded object (single vector, image, group…) you wish to have a drop shadow applied to. Via the Actions panel, select one of the 5 cut-off actions provided and click on the Play button:
The Action will start to run and then automatically open the window. Enter the settings you want but note that the transparency mode makes no difference but may be changed from the default mode once the shadow is generated. Click and the Action will complete the process.
A CMYK shadow with an appropriate flexo cut-off level has been applied correctly to each channel.
To change the transparency mode of the drop shadow, simply change the type via the Transparency panel.
Adapting the Action to apply Inner and Outer Glows
The same basic Action set can easily be adapted to apply cut-off curves to both glow types. Simply replace the Drop Shadow reference in the Action:
- It’s advisable to first replicate the original Action by dragging it to the panel’s button
- Click on the Action entry’s left-hand arrow to expand it so that you can see all steps
- Select the entry
- Click on the panel’s pull-down menu and choose and via the standard Illustrator menus select or
- OK this
- Select and delete the original entry in the Actions panel
Run the Action to test.
It’s advisable to save any new or modified Action set by first selecting the Action “folder” group entry and then via the Action panel’s pull-down menu, selecting .
Changing the cut-off curve
The cut-off levels provided should only be used as examples. It’s critical that you test, and if necessary change, the Actions provided to produce the results you require.
To change the curve in an Action is a very simple process and allows you to also define a color correction curve with a cut-off simultaneously. Here are there steps to take:
- Ensure a document is open (it can be a new blank one)
- Optional: first duplicate the Action if you wish to keep the original as a reference – although you can always re-load the Action set
- Expand the Action you wish to modify via the left-hand arrow so that you can see all the steps listed
- Double-click on the entry and modify the Curves graph to suit (you can also load a Photoshop-compatible curves settings file)
- OK’ing this change completes the process
It’s advisable to save any new or modified Action set by first selecting the Action “folder” group entry and then via the Action panel’s pull-down menu, selecting .
Shadow or glow resolution
By default, the Action produces a shadow to a 300dpi resolution, which is typically required for commercial print. It’s possible to change this value, but first you need to also ensure that the resolution defined in is of the same value. Again, Illustrator sets this to 300dpi by default for a print document.
To change the resultant shadow or glow resolution, the process is similar to changing the cut-off curve:
- Ensure a document is open (it can be a new blank one)
- Optional: first duplicate the Action if you wish to keep the original as a reference – although you can always re-load the Action set
- Expand the Action you wish to modify via the left-hand arrow so that you can see all the steps listed
- Double-click on the entry and modify the resolution value to suit
- OK’ing this change completes the process
Caution with using different transparency types
By default the Actions define the shadow’s transparency mode as Multiply. This mode, along with the alternative Darken mode ensures that the ink levels never go below the shadow’s cut-off levels. If however, you change the transparency mode to alternative modes such as Lighten, it’s likely that you will end up with a shadow that has ink levels below the required flexo drop-off point.
Why does the Action add a spot color to the document?
The approach used makes use of an anomaly within Illustrator CS3 and above where a spot color reference made in a Graphic Style doesn’t automatically get added to the Swatches panel. In fact, if you run the Action, even though the referenced spot color has been used to generate the cut-off shadow, it doesn’t feature in the final results and therefore shouldn’t appear in the Swatches panel at in the end. However, a reference to a red may appear in Phantasm CS’ Quick Separations tool (not the full separations system) and Illustrator CS4 and above’s Separations panel.
If the spot color does appear unnecessarily in the Swatches panel (it should never feature when outputting the work if the Actions work correctly), simply select it and delete it. A reason it may make an appearance is if the process of generating the shadow was stepped through backwards via the undo system.
How the Actions works
This last section is for the curious and isn’t essential to understand in order to use…
It’s not possible to fully describe the entire process in detail. However, it has been very carefully developed over many iterations to ensure that the results are faithful when applied to any embedded artwork type including vector and raster images.
The basic steps used are as follows:
- Copy and paste the selection behind the original and group it (in case multiple objects were selected)
- Apply a Graphic Style of a single Duotone live Effect which references a single temporary spot ink – ie. the original CMYK artwork is now a spot color monotone maintaining all tints and transparency levels of the original
- Expand the Duotone (to remove reference to a live Effect) and request the user to define a Drop Shadow
- Expand this again and rasterize maintaining the spot ink – ie. producing a multi-ink image
- Remove the temporary spot channel in the drop shadow image by the use of a Phantasm CS Swap Channels live Effect defined in the second Graphic Style (this was the clever bit to remove all trace of the original artwork in the shadow)
- Expand appearance one more and convert the shadow image to CMYK to ensure the result is not referred to as a multi-ink image
- Apply the cut-off curve using the Phantasm CS Curve Filter to what is now a simple CMYK image with no transparency
- Apply the Multiply transparency setting to ensure that the result appears to work like a drop shadow
Simple!
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[...] Applying flexo cut-off curves to CMYK shadows and glows Automatically generate a cut-off drop shadow or glow based on any process CMYK color, applied to any embedded object type [...]