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Mac Tricks: Convert Color PDF Files to Grayscale/B&W

There are some occasions that we need to convert a color PDF file to black and white. For instance, a PDF file that contains many color images may be quite large in size and you wish to reduce the size by converting it to the gray version. Other reasons for the conversion could be the attempt to save colored ink, or to verify how the PDF file looks in grayscale before putting it in the printing procedure.

To achieve the conversion on a Windows PC, you have to utilize standalone programs like Adobe Acrobat Professional, third party plugins or some free/paid online websites, while on a Mac computer, things become much easier: you can use the built-in Preview app to add effect on a PDF, or change colors by applying a sepia tone on it.

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Today in this post we are gonna show you how to take advantage of the Quartz filters in Preview app to convert a colorful PDF file to the gray/black and white counterpart.

  • Open a PDF in Preview, and choose File > Export from the menu bar on the top.
  • As the Export dialog box appears, you can type a named in the Export As field for the PDF file, add tags if you like, and specify the location you want to store the file.
  • Choose Gray Tone (or Black & White) from the drop-down menu of Quartz filter.

After all these configurations, click Save button to export the file in target location. The saved PDF file should be stripped of the colors except the one(s) you choose. Generally, the gray version may be more comfortable in visual than B&W version. And it’s notable that depending on the content and layout of the original file, the newly created one may not look exactly the same as it has not be converted before. Next time you would like to print a color PDF file in black and white, you can apply this trick to finish the conversion and check the effects before sending it to the printer.

By the way, if you need to convert PDF files on a frequent basis, you can take advantage of the built-in Automator app to create an automatic workflow, which will help you expedite the job. Wanna know more about this trick? Read on please.

  1. Launch Automator via Spotlight or from Applications/Utilities folder in Finder.
  2. Choose workflow as the type for the document, and click Choose button below.
  3. On the left pane of the open window, click Files & Folders under the Actions menu, and drag Ask For Finder Items from the sub-menu to the blank space on the right side.
  4. Again, drag the Copy Finder Items option to the right pane below Ask For Finder Items. Then assign a folder in the To drop-down menu as the destination converted files. And you can choose to whether check the Replacing Existing Files option or not. 
  5. In the PDFs sub-menu, drag Apply Quartz Filter To PDF Documents to the right below Copy Finder Items, and choose Gray Tone from the Filter drop-down menu.
  6. After the customization, head to the File > Save in the menu bar on the top.
  7. Type a name for the customized workflow, and save it to the Applications folder.

Dragging a color PDF file and drop it into the app icon will process the conversion automatically, and converted files will appear in the location you desired before. So that’s how to batch-convert color PDFs to grayscale. Thanks for reading this post.