PDF Optimization

3.1.2. PDF Optimization

Reason to optimize PDF documents

By optimizing a PDF document, we could reduce the file size of the PDF document. This helps in speeding the online viewing of the FlipBooks for FlipViewer and the downloading of the FlipBooks for FlipViewer.

Background

There are three basic types of PDF document:

Rasterized: The information in the PDF document has been rendered as a straight bitmap (usually very high resolution). No font or vector information remains. The PDF document is neither searchable nor editable.
Vectorized: The information in the PDF document has been converted to pure vectors. All the text characters have been converted to vector shapes and are no longer recognized as text. The PDF document is neither searchable nor editable.
Editable: Such a PDF document retains the font and text information. The PDF document may still contain some vector and bitmap information, but the text is still recognized as text. The information of the fonts is stored in the PDF document so that the latter looks the same on any machine, regardless of whether the font is installed or not. The PDF document is searchable and editable.

Before optimizing PDF documents

The PDF document that we are going to optimize should be of Editable type. In other words, the fonts are embedded/stored in the PDF document and the text can be selected, searched and treated as text.
The “rule of thumb” is optimizing the file size of the PDF document under 250K bytes per page. This figure is not fixed and only served as a good target.

Steps to optimize PDF documents

Step 1. Add Adobe PDF Setting

1. In Adobe Acrobat 7.0, choose Advanced > Adobe Distiller to open Adobe Distiller. An alternative way to launch Adobe Distiller is through Start >Programs >Acrobat Distiller 7.0.

2. In Adobe Distiller, select "Smallest File Size" from Default Settings drop-down list (refer to figure below).

3. Select Settings > Edit Adobe PDF Settings… .

4. Click the Save As… button to save this new Adobe PDF Setting File (.joboptions) as another name. For example, save this new Adobe PDF Setting as “PDF FlipBook.joboptions”.

5. Under the General tab, set Compatibility to “Acrobat 6.0 (PDF 1.5)” and set Resolution to “150” dots per inch (refer to figure below).

6. Select Images tab. For Color Images and Grayscale Images, set Image Quality to “Low” (refer to figure below). If publisher wants to have higher quality images and could tolerate higher file size, publisher could set Image Quality to “Medium”.

7. For Monochrome Images, set Downsample to 300 pixels per inch. This setting is suitable for contents that have English text. However, if the contents have Chinese text, under Monochrome Images section, set Downsample to 500 pixels per inch (refer to figure below). This will increase the clarity of Chinese words for more comfortable reading.

8. Under Fonts tab, make sure the Embed all fonts and Subset embedded fonts check boxes are selected and set to 100% (refer to figure below). If your PDF contains foreign-language fonts (i.e. Chinese, German, French, Japanese, Korean, etc), the Embed all fonts check box will make sure that those fonts needed to view the PDF are embedded into the PDF.

9. Under Color and Advanced tabs, we do not change anything and their settings are as shown in the images below.

10. Click the OK button to confirm the settings and exit Acrobat Distiller.

Step 2: Optimize the PDF document in Adobe Acrobat

1. Open the PDF document you want to optimize in Adobe Acrobat.

2. Choose File > Print. From the drop-down list of printer name, select “Adobe PDF” (refer to figure below).

3. Click the Properties button besides Printer name. Select the Adobe PDF Conversion Settings tab. From the drop-down list of Default Settings, select “PDF FlipBook”.

4. Click the Add button besides Adobe PDF Page Size. Give a new name for Paper Names. Then enter the width and height of your PDF document (refer to figure below). Click the Add/Modify button to confirm.

5. Select the new paper size that you have added in step 4. Click the OK button to close the Adobe PDF Document Properties dialog box.

6. Make sure that the size shown at the Preview section is the same with your PDF document size. Click the OK button to start distilling/optimizing your PDF document.

7. You will be prompted to save the optimized PDF document in a folder. Browse to select a folder and give a file name. Click the Save button to confirm. Your optimized PDF document will be stored in the folder after optimization has finished.