In 2006 they announced a complete rewrite of their RIP technology, called the Adobe PDF Print Engine (or APPE). Should each object, in turn, be blended into the background or should it be done on the entire group? Older prepress systems can really slow down when they need to flatten transparency.Īdobe was well aware of these issues.
On top of all of this software applications needs to work out how to best handle groups of objects that are transparent. This is frequently the reason why text fattens up a bit on output. Under some circumstances, software needs to partially convert a vector object to a bitmap. Sometimes transparency involves the interaction between a vector-based object, such as text, and a bitmap object, such as a digital photograph. Issues with color handling can show up as color shifts in (part of) an image. Making an RGB image slightly translucent on top of a CMYK background is another example. Adding a drop shadow to a spot color element that sits on top of a CMYK background (or vice versa) is an example of a design that challenges the RIP or workflow that needs to process the job. The stitch between atomic zones can sometimes show up on-screen (and even in output) as thin white lines.Īnother stumbling block is the fact that a PDF file can contain transparent objects with different color spaces. The effect of transparency is then calculated for each separate atomic zone. To simplify things, applications tend to split up a page in small square areas, called atomic zones.
The Adobe technical documentation on it is over 100 pages long. Transparency is a very complex technology. The challenges when transparency is flattened Suddenly prepress departments all over the world were flooded with designs that included transparency and their RIPs had to flatten this transparency to be able to make proofs or output plates. This process is called ‘flattening’.Īdobe also included transparency support in InDesign and they heavily promoted its use to the designer community. Other applications like Corel Draw had already supported transparency for years but had to resolve to a trick to generate a printable file: when creating an EPS file or printing a drawing, the application had to remove or calculate the transparency effects. Transparency was ‘the’ big new feature in that release. This PDF release came to market around the same time that Adobe Illustrator 9 was launched.
PDF 1.4 (the file format supported by Acrobat 5) was the first version of PDF that supported transparency. It can be used to create a tint of a certain color or mix colors.Transparency can be used to lighten (parts of) images so that the text on top remains readable.It can be used to show parts of objects that are normally hidden from view.Adding a drop shadow to text or images is one of the most popular uses of transparency. It makes underlying image objects shine through, so it is useful for emulating glass, fog, varnish but also shadow.This effect can be used for a number of reasons: Transparency in PDF files refers to objects on a page, such as images or text, which are transparent or ‘show through’.