The name is Preview… Separations Preview

Despite this magnificent feature being introduced since the first release of Creative Suite, I am still amazed at the amount of people who either don’t use this preview, or know it exists.

For those who don’t know what i’m talking about, Separations preview is a way of viewing the InDesign file so that it more closely resembles what it will look like once printed. It also lets users toggle through the ink separations which are available in the document.

Using separations preview it is possible to determine common prepress errors such as:

  • Unwanted overprints, such as white overprints suddenly disappearing from view;
  • Items set as either non-printing objects or non-printing layers (they will disappear completely from view);
  • Undesired black overprints, such as a solid black overprinting a photograph and still having the photograph visible instead of knocking out;
  • With the exception of photographs – real blacks instead of faux blacks (e.g. items meant to be 100% black only but instead composed of all four process colours);
  • Effects which won’t work with spot colours such as color burn, soft light or overlay (the areas over spot colours using these effects will dissappear);
  • The use of Registration colour (will appear on every single separation as a solid);
  • Any spot colours which shouldn’t be in the document – either because they aren’t actually in the design but are still in the swatches palette; or if they were meant to be converted to process using the ink manager;
  • Unwanted knockouts, such as a dieforme overlay which wasn’t set to overprint and has knocked out the artwork underneath it.

Similarly, Adobe Acrobat has a separations preview but goes some steps further such as:

  • How the artwork will appear based on different colour profiles; or to simulate black ink and paper appearance;
  • Can show whether the images in the PDF are CMYK or other colour spaces, such as LAB, RGB etc.

This is only using separations preview as well… haven’t even mentioned the Ink Limit view available in both Acrobat and InDesign; or the Flattener preview available in InDesign… but will save them for another post.

“Spot” the difference of soft light with overprint preview

I recently found myself being the “bad guy” after having to instruct a customer to resupply their artwork given that many of the effects applied to the pictures in InDesign would not print as desired.

In short, the artwork was an annual report printed in full colour plus a metallic silver spot colour. Originally supplied PDF only, everything looked fine on first glance with the overprint preview off. However, while the document was being manually preflighted using Acrobat’s Output Preview, I had noticed that a greyscale-like effect on the silver had disappeared once I had entered the Output Preview. Concerned, I restarted Acrobat to make sure the glitch was not software related, but again the same thing appeared. This happened on several machines and it soon became apparent that the artwork would in fact print as it appeared in Output Preview rather than the normal preview.

The customer was then contacted and informed of the situation. After replying that the artwork looked fine on his screen, the customer was then instructed to turn the overprint preview on within InDesign, and lo and behold… he began to see what I saw. He then told me he had used the soft light effect.

To demonstrate the phenomenon, I have created a new InDesign file with five elements: a rectangle coloured with Pantone 871C; a rectangle coloured with the default green which ships with InDesign; a stock photo with the soft light effect applied , and two captions of the colours in the rectangles. In the before image, the Separations preview is turned off.

and this is how the InDesign file looked after the separations preview was turned on:

resulting in the image disappearing from Pantone 871C rectangle. However, the image still appears over the process green rectangle.

Ultimately, this means that the effect is only reproducable over process colour, and not spot colour, regardless whether it is metallic or not.

Interestingly as well was the fact that in Live preflight, there was no error warning of this particular feature of the soft light effect, so if I was purely to obey the live preflight and not check my file with the separations preview or overprint preview, this would have been completely missed.

The lesson here? Always check artwork using the separations preview to make sure the artwork will appear as designed, and that some effects will work in process only.

To Overprint or not to Overprint? Black is the Question!

To compensate for misregistration on a press, printers often ask that the colour black be set to overprint so that any misregistration cannot be seen.

However, black fills placed over coloured panels or scans which have overprinted can still be seen through the black ink. Overprinting black is recommended for lines under 2pt thick or type under 60pt, not necessarily for all black fills.

This is a particular concern in Adobe InDesign as by default, all solid 100K generated in the InDesign using the [Black] swatch (that is, not in graphics placed into InDesign) will overprint unless the default is changed in the preferences.

How to find the “appearance of black” options in Adobe InDesign. By turning OFF the checkbox highlighted in RED, all blacks made in Adobe InDesign will now knock-out. Also note how the black appears in this dialog box… all blacks are being displayed as Rich Blacks rather than Accurately which is a better option and should have been used for this example.

When placing black fills, consider what is underneath the black overprinted fill. If the job is CMYK, consideration may also be given to using a “rich black” which will give a dense black and prevent the black from overprinting, knocking out whatever is underneath the fill.

If a black DOES need to knock out while keeping all other blacks overprinting, it is possible to make another black swatch as only the default black (has square brackets around it e.g. [Black]) will overprint by default. e.g.

and so that it can be easily identified amongst all the other swatches which may be in the palette, how about an appropriate name such as “Knockout Black” for example?

Among printers, there is debate about what constitutes an ideal “rich black”. Some argue that it is 60% Cyan and 100% Black; others argue various percentages of Cyan, Magenta, Yellow and 100% Black; but for me the values 30% Cyan 30% Magenta 30% Yellow 100% Black has worked for me for years.

The following picture demonstrates various fills in an InDesign file.

The next picture illustrates what happens once the various fills are printed.

In this example, it is clear to see that “White Overprint” has simply disappeared. Beneath the Black Overprint, it is still possible to see the headlights of the traffic trails of the photograph underneath. While Registration does look almost like a super black, what can’t be simulated on-screen is the effect that solid registration has on paper, over-saturating it and making it distort. Other reasons not to use Registration Colour as a fill can be found in the Registration Colour post.

Considerations should also be made when using Blacks with Metallic inks, as Metallic inks are opaque and block out the inks beneath them, unlike normal inks which add to the colours beneath them. See the Metallic Inks post for more information.

Controlling black overprints is often best left in the hands of a prepress operator, but I do believe that forewarned is forearmed.

Metallic Inks

Unlike most inks, metallic inks are Opaque – that is, they are not transparent like process colours. Instead, they block out any other colours which printed before their run on the press, and are quite viscous and thick (have a low-tack rating) and take a long time to dry.

Before preparing artwork with metallic inks, please talk to your printer. This is because drop-shadows, black type/solids and objects/rasters over the top of metallic inks with effects such as multiply or darken may not print as they appear on screen.

Quite often to achieve the on-screen appearance, printers may use what is known as a “dry trap”, meaning the metallic ink will be printed in one pass, then left to dry, and once the ink is dry, the other colours are run in the next pass. This can also be done in reverse, but the end result is the same – two passes through the press, which not only takes longer, but means misregistration is more likely due to paper stretching as ink dries, and will cost more in press time.

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