'Transparency' header

How to use transparency in your design

Can’t work out why there’s a strange box or colour change around an object when you print your file?

Firstly, what is meant by the term?  Transparency in design can refer to the obvious, such as a translucent box which allows the background to be seen through it; but it also refers to things like drop-shadows (a very common effect) and blending modes.

 drop-shadow illustration

Transparency can be a very useful tool in a design: it can make objects ‘pop out’ of the page and appear three-dimensional, giving your design depth; it can allow text to be read when on a similar-coloured background; it can allow one element to blend seamlessly into another.

However, transparency will result in some strange effects if not implemented properly.  The most common result is a strange box around the object which uses transparency.

drop-shadow gone wrong illustration

This is known as ‘stitching’ and is a difficult to get rid of if you don’t know what you’re doing.  Sometimes it won’t be a white box – it will be a box of similar colour to the background: similar, but not the same.  You may not even see the difference on screen, but you will in print.

What’s happening?

It may seem like the software is simply ruining your precious design out of spite.  Actually, a printer must have artwork made of pixels (rasterized), not vectors (which includes text and anything not photographic or already rasterized).  If the printer receives vector artwork or a combination of vector and raster, it will ‘flatten’ the image in order to print it.  That’s not to say you shouldn’t supply vector artwork—you should—but you must create it in a way which the printer will interpret correctly and rasterize reliably.

Those bits of your artwork which interact with transparency will be flattened – rasterized by the printer or the software so that the printer simply sees an image, rather than a collection of complicated vector graphics.

OK, when will it be a problem?

There are four main areas of concern: solid areas of a single colour; spot colours; text under transparency; different colour modes.

Solid colours: refers to a single colour (not photographic but created in the software).  As with the drop-shadow example earlier, colour changes can occur in the solid area when transparency is involved.

Spot colours: Pantone (or other) spot colours simply will not work well with transparency.  Don’t bother trying.  Unless you’re printing Pantone colours intentionally, the Pantone will be converted to CMYK anyway, so start the way you mean to go on.  DO NOT put any effects on top of a spot colour.

Text: when text (always vector, unless in Photoshop or similar) runs under a region of transparency, that area of text will become pixels instead of sharp vectors.  What usually happens is that this part of the text becomes slightly fatter than the rest and looks…well…pixellated.

 text under transparency example

Colour modes: refers to RGB, CMYK, etc.  You should always be using a single colourspace within your design, depending on its intended use (RGB for on-screen work, CMYK for print).  When you try to mix objects of different colourspaces, the software or printer will have to convert the colours itself, leading to mismatches.  This is especially true when using transparency.

Illustrator has a flattener preview, which you can use to see what elements are likely to cause problems in print.  InDesign has a tool which highlights elements which will be flattened using the various presets.

So what do I do about it?

In design, as in anything else, it is much easier to start properly than it is to correct a mistake later.  Make sure all the elements in your design use the same colourspace; don’t mix spot colours with transparency; don’t put effects on top of text; be aware that areas of solid colour with transparency will need to be flattened properly.

Many problems are dealt with in the file output stage.  You should be outputting to PDF format, preferably PDF/X for print (PDF/X-1 for litho, PDF/X-3 for digital).  When creating the PDF, there is usually an option for using flattening presets.  If your design is fairly simple and doesn’t use transparency, the ‘High Resolution’ preset is fine.  If transparency and other effects have been used, set the flattening to ‘Medium Resolution’ and this will sort out most problems.  If issues still occur, the ‘Low Resolution’ preset will shift the balance even further towards a totally flattened file, giving the software more flexibility in what it chooses to rasterize.  Don’t be put off by the terms ‘medium’ and ‘low’ resolution – it’s not the same thing as making a low-resolution file.

 screenshot for PDF settings

Checklist:

  • Areas of solid colour need to be flattened correctly
  • Spot colours do not play well with transparency
  • Text must be on top of transparency
  • Elements should all be in the same colourspace
  • Use PDF/X format
  • Use the ‘Medium Resolution’ flattening preset

Advanced settings

Still have problems?  The standard presets not solving your problem?  You can customise the flattening to better suit the effects you have used.

 screenshot for advanced PDF settings

 

Checklist:

  • Raster/Vector balance: 75 is fairly safe
  • Line art and Text to 600dpi
  • Convert text and strokes to outlines

No?

At the end of the (long, probably) day, if you can’t fix any problems, maybe we at Firstpoint can.  If we can’t fix a dodgy PDF, maybe we can use your original artwork and fix the source.