PDF as a file format, known as portable document format, characterized by a realistic reproduction of the original content, closer to the picture form.

In the actual use of the process, we found that some PDF documents can be like Word documents, you can edit and modify, copy and paste and other operations, but some of them are the same as the picture, you can not select the text, naturally, can not be edited and modified. So why is this?

First of all, the ability to edit PDF documents are usually directly from the text document conversion. These PDF documents can generally be modified to edit, and support copy and paste the content.

Secondly, there is also a situation is also directly converted from a text document to a PDF document,merge pdf rearrange pages but in order to maintain the original document's original flavor, or for copyright and other considerations, to prevent arbitrary modification, will be encrypted. Such PDF documents can not be edited as well.

In addition, there are some PDF documents are converted from images or scanned documents. Such PDF documents can not be edited.

For PDF documents can not be edited, there are some powerful PDF document conversion tools on the network can be used, they can be converted to text mode. Of course, this depends on the software's ability to recognize and decode.

In addition, there are now some intelligent screen recognition functions on the phone, you can extract the text from the picture. However, it should be noted that this extracted text needs to be proofread later.