Is there an app that automatically trims the photograph of a document and leaves only the document itself without the background where it has been photographed?
Do you mean a PDF viewer that removes all images? I have not come across this feature, personally. It may exist in an app(s). Are you concerned about binary in PDF documents?
I mean to automatically trim an image (in jpg format, for example) so that there is just the photo of a written paper or page, which is what you wanted to photograph.
Open Note Scanner (Scan documents, handwritten notes or arts)