GIF) or cause an irreversible loss of image data (JPEG). Be aware also that saving original graphics in some graphics formats will either reduce the number of colors (e.g. If the original graphic is not of sufficient quality, nothing will help.
#EDIT VECTOR GRAPHICS IN ACROBAT PDF#
Graphics quality can only deteriorate during conversion to PDF, or when the PDF is displayed. Make sure that your original graphic has the level of detail or color depth needed. EPS can contain both vector graphics and bitmap graphics.įollowing are general recommendations and guidelines to improve the handling of graphics in your PDFs. Some vector formats (WMF, for example) support bitmaps as a component.
Authoring tools, such as Microsoft Word or Adobe FrameMaker, include their own vector graphics tools, which are directly carried to the PDF during distilling. Because of this, a PDF with vector graphics can be viewed at various magnifications (effectively different resolutions) with no degradation or loss of quality.Ĭommon formats for vector graphics include WMF, SVG, and CGM. It will always display/print at the highest resolution of the output device used.
When you have layers or gradations implemented as multiple objects, Acrobat’s display process shows different objects temporarily displayed and then covered partially - which may sidetrack the reader’s attention.Īs a vector graphic is independent of display/output resolution, it can be scaled or rotated flexibly.As the rendering result is not cached by Acrobat, the slower display is experienced every time you zoom in/out or go the next page and back.
Complex multi-component drawings may challenge Acrobat’s drawing functions, resulting in a painfully slow painting process that involves many thousands of segments.Thin lines may be displayed with inconsistent line thickness.Vector graphics can also pose some difficulties when displayed in Acrobat: However, when vector graphics try to imitate a photograph, the look can be synthetic or technical. In fact, they can often be clearer in detail than a photograph, enabling you to emphasize the important details and eliminate or minimize details that cause visual noise. Vector graphics work best when real-life photographs are not necessary. Vector graphics are a list of drawing objects (such as lines, arcs, curves, circles, and rectangles), encoded as textual or binary instructions. Rotating bitmaps using angles other than 90 degrees also causes images to be distorted.Ĭommon bitmap formats include BMP, GIF, TIFF, JPEG, and PNG. This process is known as resampling, and results in degradation of image quality. When a given bitmap is displayed using a different number of pixels, let’s say a 100-by-100-pixel bitmap is displayed in an area of 160 by 160 pixels, or in an area of 90 by 90 pixels, some pixels are added or eliminated. The number of pixels in a given area is known as resolution, commonly expressed as dpi (dots per inch) or ppi (pixels per inch).īitmaps are resolution-dependent, which means that for optimal display in Acrobat, there must be a match between the pixel matrix stored in the graphics and the display pixel matrix. Bitmaps are the native format of photographs, scanned images, and screen captures. Graphics are stored as a computer file in two distinct ways: bitmap and vector.īitmap graphics are a collection of dots called pixels (picture elements), arranged in a matrix, each pixel with a different color value. The manner in which graphics are displayed in a PDF depends on a number of factors, including the source graphics, its graphic format (vector/bitmap), the bitmap resolution as indicated in the authoring application, the distilling job options, and the viewing preferences. And because of the many issues involved, there are invariably trade-offs and compromises to be made. Factors such as graphic format, image resolution, and color depth all depend on the specific use of the PDF. Editor’s Note: The following article was written with Acrobat 5 in mind and does not specifically discuss the recently released Acrobat 6, although it has been reviewed for accuracy and relevance to the new software.Īny discussion of graphics in PDFs is inherently closely related to the specific content, intended uses of the PDF file, and the function of the graphics within the file.
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