The final size of a PDF file is a function of two primary issues related
to graphic images used on each page:
- The actual size, in inches and pixel resolution of each graphic image in the original document.
- The resolution settings for graphic images (image quality) chosen when creating/printing the original document to PDF.
To minimize scanned or digital camera image files, all operations should be done prior to placing them on the page of the original document to be converted to PDF format.
Determine the actual size that the image will be when placed on the page of the document and then either create the graphic at that size, or using an image editor reduce the graphic to the actual size it be when placed on the 8.5 x 11 page.
Optimal image resolution for laser printing is 300 dpi.
Optimal image resolution for computer screen display is 100 dpi.
If the images need to printed for critical analysis - use print resolution. Otherwise screen resolution should be fine and will reduce the image file size by at least a factor of three. i.e. 1 MB vs 3MB for an average size image. Of course, the more images in your document, the larger the final PDF file will be. Plan ahead and work carefully to ensure optimum use of image size controls.
If final images are greyscale - convert to greyscale not RGB to help
minimize file size.
When creating the PDF file the following settings in the create/print dialog box will help to minimize the final size of the PDF file:
- Screen resolution for email or display on computer monitor Color/Greyscale images - compress using JPEG low
- Print resolution for printing to laser printers Color/Greyscale images - compress using JPEG medium