Image Type & Purpose

QUIK! TIP: Use as few images as possible to keep file size to a minimum. When using images, use bitmap or native file types.

When designing a form, images can be used to provide information not easily described with words. The most common use of an image on forms is for a company logo. In the cases where companies have used an image as a background image for the document, the document was unnecessarily large – by a factor of 10 or 20!

The type of image used can affect the resulting file size of the PDF. If the program used to author the form allows images to be created within the program (i.e. the artwork is ―native‖ to the program) then the type of image used is less important when the PDF is created.

If the program used to create forms requires images to be imported, then the type of file used will have a direct affect on the quality of the resulting PDF and the file size of the PDF. The most popular image types are Bitmaps (*.bmp), JPEGs (*.jpg), GIFs (*.gif) and TIFs (*.tif). Bitmaps are large uncompressed images primarily used by Microsoft Windows and Office applications – for example, a computer screen shot made in Microsoft Windows will result in a bitmap image.

The images below were created in Microsoft Word and then converted into a PDF. These images show the varying quality of each image type on a PDF:

Image Size

QUIK! TIP: Use the smallest image file sizes as possible – the larger the image, the larger the PDF will be.

The larger the image, the larger the size of the resulting PDF will become. Since PDF file size affects the performance of the PDF as an electronic form, including how long it takes to generate and download the form, the file size is an important consideration. Thus, limiting the use of images, especially background images and watermarks, is very important to the end-user’s experience with the form.