PDF files are an excellent medium for online documents because they work on virtually all platforms and Web browsers. Color PDF files, however, are sometimes too large for site visitors that have slower Internet connections and can take a considerable amount of time to download or view. Therefore, you should convert larger color files to smaller grayscale (black and white) PDF files.
Adobe Acrobat 8 Professional
Open Adobe Acrobat 8 Professional on your computer. Click the "File/Open" option on the menu bar and then browse to the PDF file you want to convert. Highlight the file and click the "Open" button.
Click the "Advanced" tab on the menu bar and then click "Print Production/Preflight." After the "Preflight" dialog box opens, click the small triangle symbol next to the "PDF Fixups" label.
Click the "Convert to Grayscale" link and then "Execute." Wait while Acrobat converts the PDF to black and white and then click the "File/Save" option to save the changes.
Adobe Acrobat 9 Professional
Double-click the desktop icon for Adobe Acrobat Professional to launch the application. Click the "File" option on the menu bar and then "Open." Browse to the folder on your computer that contains the PDF file you want to change to a black and white format. Select the file to edit and then click the "Open" button.
Click "Advanced" on the menu bar, click "Print Production" and finally click "Preflight."
Click and select the "Convert to Grayscale" option under the "PDF Fixups" header. Click the "Analyze and Fix" button to convert the PDF file to black and white. Save the new PDF file with the "File/Save" option on the menu bar.
Open Adobe InDesign on your computer. Then click the "File/Open" link at the top of the screen. Next, browse to the InDesign PDF file you want to convert to grayscale and click the "Open" button.
Ensure the "Adobe PDF Printer" is the active and default InDesign print device option by clicking "File/Page Setup" on the menu bar.
Click the "File/Print" link on the menu bar. Before printing the PDF, change the "Color Output" setting under the "Advanced" tab to "Composite Gray." Click the "OK" button and InDesign will generate a new black and white version of the PDF file. Give the grayscale PDF file a new name and save it on your computer.