About PDF files

About PDF files

The PDF file format is a PostScript-based document format that accommodates PostScript-based graphics and text, as well as bitmap graphics. Areas of transparency in a PDF file are also transparent in Motion.

PDF files are capable of storing PostScript-based illustrations. Unlike graphics file formats such as TIFF and JPEG, which save images as a collection of pixels at a given resolution divided into red, green, and blue channels, PostScript-based illustrations are saved as mathematical descriptions of how the artwork is drawn. As a result, PDF files using PostScript-based artwork and text have infinite resolution.

The practical difference between bitmap files and PostScript-based files is that scaling a bitmap beyond 100 percent results in the image progressively softening the more you increase its size. PostScript-based illustrations remain sharp and clear no matter how large or how small you scale them.

When importing a PDF file, its size is relative to the original page size of the file. As a result, even small graphics can have a large frame size, with empty space surrounding the graphic. When exporting a graphic as a PDF file for use in Motion, you may want to scale the graphic to fit the page dimensions, or reduce the page size in the source application’s page preferences to fit the graphic’s dimensions.

Fixing the resolution of a PDF object

Although PDF files have unlimited resolution, large PDF objects can consume a lot of video memory, which can hinder performance in Motion. To avoid this problem, limit the resolution of each PDF image to save video memory. By using fixed-resolution parameters, the files are rendered once, ensuring better performance.

The fixed-resolution parameters for PDF objects are adjusted in the Media Inspector. Select the PDF source media in the Media list to activate the Media pane of the Inspector. Adjust the following controls to modify the PDF’s fixed-resolution parameters:

  • Pixel Aspect Ratio: A pop-up menu to assign a nonsquare pixel aspect ratio to the file. In most cases, the “From file” menu option is the best choice because it assigns the PDF source file’s native aspect ratio. Choose a different menu item only if you want to override that native setting.

  • Fixed Resolution: A checkbox that, when selected, fixes the resolution of PDF source media to the size specified in the Fixed Width and Fixed Height sliders.

  • Fixed Width: A slider to set the maximum horizontal resolution to which a PDF object can be smoothly scaled.

  • Fixed Height: A slider to set the maximum vertical resolution to which a PDF object can be smoothly scaled.

  • Use Background Color: A checkbox that, when selected, substitutes a custom background color for transparent portions of the PDF. Choose the background color in Background Color controls (described below).

  • Background Color: Color controls (available when Use Background Color is selected) to set the background color for transparent portions of the PDF.

  • Crop: Sliders (Left, Right, Bottom, and Top) to crop the edges of the PDF image, if necessary. These controls crop the PDF source media (and all layers linked to that source media). To crop an individual layer, use the Crop parameters in the layer’s Properties Inspector.

Mixed content in PDF files

Although PDF files can contain a mix of PostScript-based art, PostScript text, and bitmapped graphics, each format has different scaling properties. PostScript-based art and text scale smoothly, but bitmapped graphics embedded in a PDF file are subject to the same scaling issues as other bitmapped graphics formats. As a result, bitmapped graphics can soften if scaled larger than their original size.

Note: Form objects, buttons, and JavaScript objects that are present in an imported PDF file do not appear in Motion.

Multipage PDF files

You can import multipage PDF files. When you do, a parameter called Page Number appears in the Properties Inspector when the PDF object is selected. Drag the slider to set which page is displayed in the Canvas. Animate this parameter to display different pages over time.

Important: Multilayered PDF files are not supported. To import a multilayered illustration, export each layer as a separate PDF file and import these as a nested group of objects in Motion.