I don’t know whether this happens to you, but it surely does to me! I scan a document into my Mac either using one of my multifunction printers or my Brother Document Scanner. About 50% of the time, the PDF document scans crooked, it is skewed one way or the other. So then I scan it a few more times until I get it right. There are other ways to deal with scanned PDF files that are skewed.
Unskewing The Skew
I have done tons of research on this problem using my own Apps and online as well. I tried to find ways to fix skewed PDF files that would not cost people much money. The first place I looked was the macOS Photos App. Here is a typical skewed PDF file that is opened in the Editing area of the Photos App:
The way to remove the skew is to go into the Crop mode. Once you are in Crop you can use the adjusting wheel to straighten the image slowly:
This works pretty well with one caveat. When you use the Crop feature in the Photos App, you do lose some of the edges of your photo or document. That is no big deal. If your PDF has decent edge margins you won’t even notice it.
Some Apps have a Deskew feature. Here is the setting in PDFPen Pro:
This Deskew feature usually works in conjunction with some type of OCR capability. PDFPen Pro imports the document and asks if you wish to OCR it. If you say yes, the document is OCR’d and straightened at the same time. If you just drag a already scanned PDF file into PDFPen Pro you can still Deskew it if you access the “Deskew and Adjust Image” command in the Edit menu:
So, why not just use PDFPen Pro you ask? Because PDFPen Pro is expensive. There is no better App out there if you do much work with PDF files. If you only need an occasional Deskewing, you might just stick with the Photos App.
I found this PDFScanner App in the App Store by doing a search on PDF OCR. It gets good reviews and it appears to correct skewed documents automatically on scan or manually later. I did not wish to invest $14.99 to confirm all this, but it does seem to get good reviews. If you need OCR and skew repair capability you might give it a try. It does not do as much as PDFPen Pro, but it would be adequate for many people.
Here is something to think about. When I had bought my Brother Document Scanner it came with PageManager software which does have a Deskewing feature. Along these lines, if you have a multifunction printer, it probably has some type of scanning software available. The HP Easy Scan software that came with my HP OfficeJet Pro 8610 has a “Straightening” feature:
Once you have the document or photo scanned into the HP Easy Scan software you can access the Straightening feature in the Edit window. It is somewhat crude, but it works with some patience.
You can find some services on the Web that advertise Deskewing documents, but I thought they were pretty crude. I am sure Photoshop and other expensive editing programs have Deskewing capabilities, but who wants to pay for it.
I even downloaded the Adobe Acrobat Reader App to see if it had some type of Deskewing feature, but no joy. Of course, you can always buy Acrobat Professional for a few hundred dollars, but who can afford that.
If you know of any free or inexpensive software that can Deskew a scanned PDF document please let me know in the Comments Section and I will review it.
If you are like me, you have need of Deskewing services from time to time. There are always the Photos App or your multifunction printer software if you wish to keep it in the realm of FREE. If you are willing to invest some dinero, there are other solutions that work very well.