Easy to obtain using Acrobat XI.
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Open the PDF with Acrobat XI. Open the Tools pane. Next, select the Text Recognition pane and expand it. Now select "In This File" to recognize text (perform OCR). In the Recognize Text dialog click "Edit" and, from the dialog presented, use the drop-down for PDF Output Style to pick Searchable Image, Searchable Image (Exact) or ClearScan.
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Acrobat Help provides an informative discussion of the three output styles of OCR.
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Be well...