[EN] Transparency Flattening, Transparency Blending Space, Transparency Fill Space

In DUON, non-CMYK-based transparency blending spaces are not allowed. Transparency blending spaces of placed objects that differ from the document CMYK space are converted to the document CMYK during export from InDesign.

Since no actual color conversion takes place in this process, a corresponding warning is usually displayed when exporting from InDesign. However, this warning can be bypassed and suppressed by selecting “Do not show again.”

Such a change of the transparency blending space can lead to color shifts in objects constructed with transparency. In this case, it is necessary to correct the original data.

Setting the Transparency Fill Space Correctly

Corresponding error messages appear for PDF print files in which PDF/X-4 objects have been placed and the placed elements use native transparencies, while the transparency overprint/blend space (in newer versions: transparency fill space) is set differently from the document.

Correcting the Transparency Fill Space of Placed PDF Files

When placing PDF files with an RGB-based transparency blending space, InDesign does not display a warning; instead, it uses the set color space for display. A warning only appears during export.

Therefore, check PDF files before placing to ensure that the transparency blending space does not differ from the document CMYK. In Acrobat Pro, the Transparency Blending Space of a PDF can be viewed at the bottom of the Output Preview (Tools > Print Production > Output Preview).

You can correct the “transparency blending space at the page level” in the Flatten Preview (Tools > Print Production > Flatten Preview).

 

Select “Change” here. The following dialog will open. Choose the document CMYK color space.

 

Avoid Using Native Transparencies?

If you do not require native transparencies in the placed objects, you can easily avoid this issue by flattening the PDF files before placing them in InDesign. For example, convert them to a PDF/X standard that does not allow transparencies (e.g., PDF/X-1a:2003).

r [DE] PDF/X Standard & Version

If you need transparency interactions between the placed objects and other layout elements for design reasons, please follow the tips below for correction.