When a document is scanned using a scanner, it is usually saved as a PDF file. This scanned document is stored as an image file. If the resolution is high while scanning or if the depth of the color is large, then the document will be of large size. Storing and transmitting such large documents is not practical. However there are several different methods that can be adapted to reduce scanned PDF files. PDF converters and PDF optimizers are two such options.
Using lower resolution and scanning using grey scale will help in lowering the size but this is generally not an option when one needs high quality documents. There is software available that can be used for the technique of scanned PDF reduce. Adobe acrobat professional is one such software in which has an option to save another copy of the file. Selecting this option will automatically scanned PDF reduce the selected file. It also has two options Optimize Scanned PDF and Reduce File Size menu that can be used directly to reduce scanned PDF file size.
Sometimes, fonts used on the PDF files occupy a large space. Another technique used for scanned PDF reduce is un-embedding the font. But this should be done only if you are sure that the font is available on the receivers computer. Otherwise the document will not be supported by the receiving computer.
The size can also be reduced by discarding objects that are not required in the document. Some of these objects such as bookmarks may occupy large space but are not required for proper functioning of the document. Removing them enables scanned PDF reduce of the file. However care should be taken while doing so since these objects are selected by default and required objects too may be deleted in additions to the ones that are not needed.
Down sampling and compression can also be used effectively to reduce the sizes. Down sampling is done to reduce resolution while compression is done to remove the unwanted pixel data. Using one or all of these techniques will greatly reduce the file sizes, saving memory and making transmission faster.