Reduce PDF file size

The speedata Publisher has a new (pro) feature to reduce the file size of the resulting PDF. This works by setting a maximum DPI value for bitmap images (PNG and JPG).

How does it work?

You can set the maximum DPI value of the document with

<PDFOption dpi="120" />

for example. If you now include an image which would result in a higher number of pixels per inch, the speedata Publisher automatically reduces the image size to the given width.

Example: with this 768 by 1024 pixel image (from wikitravel):

and the following layout (which just includes this image)

<Layout xmlns="urn:speedata.de:2009/publisher/en"
    xmlns:sd="urn:speedata:2009/publisher/functions/en">
    <PDFOptions dpi="120"></PDFOptions>
    <SetGrid width="1in" height="1in"></SetGrid>
    <Record element="data">
        <PlaceObject>
            <Image file="https://wikitravel.org/upload/shared//9/93/Lisbon_Tram.jpg" width="3"/>
        </PlaceObject>
    </Record>
</Layout>

The PDF width of the image is three inches, therefore the image width is now 360 pixels (120 dpi * 3 inch = 360). The height of the image is scaled accordingly (keeping the aspect ratio).

Of course the visible outcome of the images get less pleasant the more you reduce the image. For example the last image looks like this:

This is always a trade off image byte size against crisp looking images. It surely depends on your application, for example if you want to print a PDF or view it online.