How to “decompile” a picture in pdf

Question

I’m trying to prepare the materials for an open laptop examination. The notes are given in pdf and the key factor to doing well is navigation skills. I’m on a mac and I’m usually viewing these slides with Preview.

When I’m using a Ctrl-F, the words in the picture contained on a particular page don’t get highlighted, and I understand that it’s because of the formatting of the picture. This is illustrated in the diagram below when I searched for “group”.

May I ask if it’s possible to “decompile” the picture, such that when a Ctrl-F is used, even the words in the picture are included in the search results. I have a feeling adobe photoshop can do this, but I'm not sure of the term used to label this action and I'm also relatively new to photoshop.

This means that the solution will allow all the “electron” words in the following picture to be seen in Ctrl F.

If I'm at the wrong site, please redirect me to the appropriate platform, thank you.

Answer 1

This is entirely dependent upon the structure of the PDF.

If the PDF was created from live type, then a viewer with search features should be abele to detect the type. I can't speak for Preview directly on the Mac. I've always found it insufficient for anything other than "look at that". Using Adobe Reader/Acrobat may yield better results.

However....

If the PDF was created from a flat image file, such as a jpg, Then there will be no "live" type within the PDF and no "searchable" content.

In some instances you can use OCR (optical character recognition) options to detect text characters and essentially construct type which may then be searchable. OCR can be overall accurate and usable for such a task, but it is often not 100% accurate.

I don't believe Preview will work for this. Preview is a viewer not a "worker". Adobe Acrobat has built in OCR functionality. And I'm certain there mush be other PDF viewers out there (freeware/shareware) that have OCR capabilities.