How to merge scanned documents into one PDF file

Key points of this article

If there are already several PDFs, just merge them directly without converting the format again.
Scattered scanned images must be assembled into a PDF first, and then merged and sorted
Check page number, page order and direction page by page after merging, which is less troublesome than finding missing pages afterwards.
When you need to search or copy text, perform OCR recognition on the entire merged document
OCR results may contain typos, and key numbers and signature pages must be manually checked

Many people have several scanned pages or several scanned documents saved separately. When submitting materials, sending them to colleagues or printing, they all hope that they will be just one file. How to merge scanned files into a PDF is essentially a matter of page assembly, not format conversion.

This article is for those of you who already have scanned copies and just want to put them together into one copy. The following will first give judgments by file type, and then list the operation steps and combined checklist. After reading this, you should be able to judge which path you should take, and know where things are likely to go wrong after merging.

How to merge scanned documents into one PDF? One sentence conclusion

If there are already several PDFs, use the merge function of the PDF editor to put them together, and then adjust the page order; if there are scattered pictures, organize them into one PDF first, and then merge them.

your situation	Recommended practices	reason
Several separate scanned PDFs	Merge in PDF editor and check page order	The file itself is already a PDF, just splice the pages
Multiple pictures scanned from a stack of paper pages	First assemble the images into a PDF and then merge them	The image is not a PDF and needs to be converted into a file first
The order of pages in a PDF is out of order	Adjust using page rearrangement and rotation features	The problem is in the page order and orientation, no need to rescan
Need to search or copy text after merging	Perform OCR on the entire document	The scanned document is essentially an image, and OCR will add identifiable text.
Just need a few pages	Split or delete pages after merging	Merge first and then delete, which is less likely to miss pages than selecting them one by one.

Before you start: Confirm these points first

Spend a few minutes making judgment before taking action, and you'll save a lot of rework later.

Determine file type. Use a file manager to see the extension. If it is a .pdf, you need to further check whether it is a pure image scan: after opening it, try to select a piece of text. If you cannot select it, it usually means that the page is just a picture. This determines whether OCR is required after the merge.
Arrange the pages in order. If the pages are not numbered, arrange them in order before scanning. Arrange the page order before scanning, which saves effort compared with dragging page by page after merging.
Check orientation and clarity. Pages that are laid out horizontally or upside down will still be like this after merging and need to be noted down. Blurred pages will still be blurry after being spelled out. If a clear version is missing, you should scan it again as soon as possible.
Backup originals. Merging will generate a new file, do not delete the original scan, keep a copy for comparison of page number and content.
Consider file size. Scans with many pages and high resolution may be larger in size when combined. Confirm the size limit of the recipient before sending; if it exceeds the size limit, you can split it into several parts by chapter and submit them separately, and confirm with the other party.

Steps to merge scanned pages and adjust their order in OmniDoc

The following steps are suitable for situations where you already have PDFs or images that need to be assembled into one file.

Open the OmniDoc desktop client (download address: download.omnidoc.top) and enter the PDF editor.
If the original material is pictures, first assemble them into a PDF in page order. You can use the system's built-in print to PDF function or the export function of desktop office software to ensure that each picture is one page.
Open the first PDF in the editor, use the merge function, and add the remaining files one after another and arrange them in the expected order.
After the merger is completed, write down the total number of pages and compare it with the number of pages in each document.
Use the page rearrangement function to drag the misplaced pages to the correct position. Compare the page number or content on the paper page by page.
Use the rotation function to correct horizontal or upside-down pages.
If you need to search or copy text, perform OCR recognition on the entire document.
Export or save as new file. The page number and date are noted in the file name, and the original scan remains intact.

Check each item after completion

After you get the merged results, don’t send them out directly. Go through the list below.

Check items	How to see	What to do if there is a problem
Total pages	Compare with the sum of the pages of each document	If the number of pages does not match, go back to the original file to check whether it has been missed or repeated.
Page order	Look through the pages one by one, comparing the number or content of the page	Drag and adjust with the page rearrangement function
Direction	See if each page is upright.	Correct it with the rotation function and confirm it page by page
Sharpness	Enlarge to see small print, form lines and seals	The blurry page needs to be rescanned, and then the original page will be replaced
Whether the text is optional	Select a paragraph of text in the document	Execute OCR when there is no text layer, and check the recognition result
File size	View the size in the file properties	If the limit is exceeded, it will be split by chapter and submitted separately.

It should be reminded that OCR is machine recognition, and there may be typos or omissions. The contract amount, date, document number and signature page should be checked manually against the original paper, not just the identified text.

# which method is suitable for you?

- prepare the submission: merge according to the order required by the material, focus on checking whether the page order and signature page are complete, and the file size should be confirmed first. - only want to be archived and retained: you can keep the original and a merged part after the merger. OCR is optional, which is convenient for future search. - search or quote the text in it: be sure to perform OCR after the merger, and spot-check several identification results. - it is necessary to split the merged parts back into several pieces: Mark the start and end pages of each part in the file name before merging, which is easier to correspond to subsequent splits.

# frequently asked questions (FAQ)

1. Can you search for text directly after the scanned pieces are merged?

Not necessarily. After the pure image scan is merged, it is still just a picture, and you need to perform OCR recognition before you can search and copy the text.

2. Can the photos taken by mobile phones be merged into a single PDF?

Sure. First assemble the photos into a PDF in page order, and then merge or use them directly. When taking photos, pay attention to the integrity of each page and uniform light, otherwise the merged text will be difficult to read.

3. Will the merger reduce the quality of the picture?

The spliced page itself should not change the content of each page. If the blur is found after the merger, it is likely that the resolution of the original scan is low and needs to be replaced after re-scanning.

4. Can the merged PDF be split again?

Sure. Use the split function to divide the document into several pieces according to the page number.

# Summary

When the scanned pieces are merged into a PDF, the key is to first distinguish between the PDF or the picture, and then use the merge and page adjustment to straighten out the order and direction. After the merger, check the number of pages and sharpness according to the list, perform OCR when you need to search, and check the key content manually.

Open OmniDoc and use the PDF editor to process your files