When scanning contracts, agreements, and archival documents, PDF pages often appear with a gray background due to paper shadows, equipment exposure, or photocopy marks, making the text unclear. From the perspective of office batch processing, this article explains how to use HeSoft Doc Batch Tool to access the PDF tool, select "Make Text on PDF Images Clearer," batch add multiple PDF files, and improve the gray-background image effect through the "Text Clarity (Binarization)" setting, making scanned PDFs more suitable for reading, printing, archiving, and subsequent recognition.
When archiving contracts, many companies scan paper documents into PDF files for storage. Over time, folders can accumulate a large number of scanned contracts, service agreements, quotations, receipt confirmations, and paper-based PDF documents. The problem is that the quality of scanned PDFs isn't always ideal: some pages are grayish, some have shadows along the edges, and some text appears blurry, as if photocopied multiple times. For a single document, this only results in a poor reading experience; for dozens or even hundreds of documents, it becomes a noticeable issue for office efficiency.
If you are searching for "What to do when scanned contract PDFs are gray and unclear," "How to whiten a PDF's gray background," or "How to batch improve the clarity of scanned PDFs," this article provides a practical method. We will use the "Sharpen Text on PDF Images" feature in HeSoft Doc Batch Tool to apply batch binarization processing to multiple scanned PDFs, making the page backgrounds whiter and the text blacker, thus enhancing overall readability.
Applicable Scenarios: Scanned Contracts, Archives, and Receipt PDFs Can All Be Processed This Way
There are many reasons for grayish scanned PDFs, which could be suboptimal scanner parameters, insufficient ambient light when taking a photo to PDF with a phone, or the original document itself being a photocopy. As long as the PDF pages are primarily composed of scanned images and the content mainly consists of black-and-white text, table lines, numbers, and clauses, they are well-suited for clarity enhancement processing.
Typical applicable scenarios include:
- Batch-scanned contract PDFs with a grayish page background and unclear clause text.
- Scanned old archives, historical documents, and paper files that have shadows and stains.
- Financial receipts, expense reports, and delivery receipt PDFs that need to be printed or archived.
- Scanned copies of English contracts, technical documents, and manuals that need improved readability.
- Preparing for subsequent OCR recognition, where reducing gray background interference first can improve image quality before recognition.
The positioning of HeSoft Doc Batch Tool is as batch document processing software. Its core value isn't to replace human judgment of file content, but to centrally handle highly repetitive, rule-defined file processing tasks. For scenarios like "many PDFs all needing the same clarity enhancement," it is more efficient than opening PDFs one by one and making manual adjustments.
Effect Preview: Gray Scanned Pages Appear Closer to Black-and-White Documents After Processing
Below is the effect of a PDF page before processing. As you can see, the page background is not a pure white, but has a noticeable grayish tint; there are also shadows at the bottom and edges caused by scanning or photographing. Although the text is present, the overall contrast is insufficient, and printing might also consume more toner.
After processing, the page background is cleaner, and the body text and titles are more prominent. The originally grayish paper background tone is reduced, and the page appears closer to a black-and-white scanned document, suitable for archiving, sending, printing, or further PDF recognition processing.
This before-and-after change is particularly valuable for contract documents. Contracts, agreements, and manuals often contain large amounts of small-font text. If the background is grayish, the reading strain increases significantly; after clarity enhancement, the page hierarchy is clearer, making key clauses, numbers, headings, and body text easier to identify.
Operational Steps: Batch Binarization Processing of Scanned PDFs
Step 1: Find the Corresponding Function in the PDF Tools
After launching HeSoft Doc Batch Tool , first select "PDF Tools" from the left navigation bar. After entering the PDF tools category, multiple PDF-related batch processing functions will appear on the right side. Based on the screenshot, you can see the "Sharpen Text on PDF Images" function, which is described as being used for batch applying various effects to images within scanned PDFs to make text clearer.
Clicking this function takes you to the processing page for this task. Choosing the correct function is important because clarity issues in scanned PDFs are fundamentally image problems, not font issues with regular electronic PDFs. Using "Sharpen Text on PDF Images" better suits optimization needs like gray backgrounds, blurriness, and dullness in scanned documents.
Step 2: Batch Add Contract PDFs or Import from a Folder
After entering the function page, the first step is to "Select records for processing." There are "Add Files" and "Import files from folder" buttons in the upper right corner of the page. For tasks like contract archiving or file sorting, documents are often already organized in folders by project, date, or client. Therefore, it's recommended to directly use "Import files from folder" to batch add PDFs from the same directory to the list at once.
In the screenshot, multiple PDFs have already been imported, with filenames like service contract - 01.pdf, service contract - 02.pdf, etc. The list also displays file path, extension, creation time, and modification time. You can check here if the files are complete and confirm that no incorrect PDFs were selected. If you find files that don't need processing, you can delete the corresponding records via the action column.
The purpose of this step is to bring originally scattered PDFs into a single processing queue. For batch office work, this is more reliable than processing files one by one and makes it easier to verify the quantity. For example, the bottom of the screenshot shows a count of 7 records, indicating that the same set of clarity enhancement rules will be applied to the 7 current PDFs.
Step 3: Enable "Text Clarity (Binarization)" and Adjust the Ratio
After clicking "Next," you enter the "Set processing options" section. In the effects area, you can see that the "Text Clarity (Binarization)" option is already enabled, with the slider currently showing an example value of 45%. The two ends of the slider are labeled "Pure White" and "Pure Black," indicating that this parameter controls the degree of separation between the image's light background and dark text.
Binarization is a very common method for handling gray-background scanned documents. Simply put, it attempts to process the light gray parts close to the background into white and the dark parts close to the text into black. In this way, the originally grayish PDF images become more like clean black-and-white documents.
However, a higher parameter value is not always better. Contract PDFs might contain seals, signatures, thin table lines, underlines, or light-colored notes. If the binarization strength is too high, some details might become too dark or be lost. Therefore, it's advisable to test with one or two PDFs first. For most gray-background text scanned documents, starting around the 45% shown in the screenshot and fine-tuning based on the results is recommended.
On the same page, you can also see switches for "Brightness," "Contrast," and "Sharpness." In the screenshot, these options are not enabled, so this article mainly focuses on text clarity. If your PDF only has a gray background and decent text, prioritizing binarization is sufficient; if the document is generally too dark, you can combine it with Brightness; if the text edges are blurry, consider Sharpness. In actual office work, simpler parameters usually lead to more stable batch processing results.
Step 4: Proceed to Save Location and Start Processing
After setting the clarity parameters, click "Next" at the bottom. Following the workflow at the top of the page, the subsequent steps will involve "Set Save Location" and "Start Processing." When batch processing PDFs, it's recommended not to overwrite the original files directly but to choose a new output directory, such as "Clear Version of Contract PDFs," "Scanned Documents Processed," or "PDF Binarization Output."
There are two benefits to this: First, the original scanned PDFs can be kept as backups; second, if you find after processing that some files have unsatisfactory results due to having more seal or image content, you can return to the original files and readjust parameters. After setting the save location, you enter the start processing step, and the software will batch-generate processed PDFs according to the list order.
The entire process only requires setting up the rules once, which can then be applied to multiple PDFs. For roles in administration, HR, finance, legal, and archive management, this batch method can significantly reduce repetitive work, especially for tasks like monthly archiving, project data organization, and historical contract digitization.
Frequently Asked Questions and Processing Suggestions
1. Why does the background become whiter after processing, but colored content also decreases?
This is because the core goal of binarization is to compress the image into an effect closer to black-and-white, which suits text-based scanned documents. If a PDF contains important content like color photographs, color charts, or red seals, binarization might affect the color rendering. For such files, it is recommended to test them individually first, rather than directly applying the same parameters to all files.
2. Do I need to convert the PDFs into JPG images before processing?
No, you do not. This uses the "Sharpen Text on PDF Images" function within PDF Tools, which can directly import PDF files for processing. Unless you have additional image editing needs, there is no need to convert PDFs into image formats like JPG or PNG first.
3. Can this function solve all blurriness problems?
No, it cannot. It is suitable for improving issues like gray backgrounds, low contrast, and faded text. If the original scan resolution is very low and the text is already severely blurred into a blob, it is difficult for any post-processing to fully restore details. It's recommended to ensure adequate resolution and lighting at the scanning source first, and then use a batch tool for optimization.
4. Why should I test a few files before batch processing?
PDFs within the same folder might come from different scanning devices, so their grayscale and clarity might not be entirely uniform. Testing a few representative files first can help determine if a binarization ratio like 45% is appropriate, before deciding to batch process all files. This can reduce rework and improve the final output quality.
5. After clarity enhancement, can I proceed with PDF to Word, docx, or OCR conversion?
It can serve as a pre-optimization step. Clear black-and-white pages are usually more conducive to subsequent recognition, but clarity enhancement itself is not equivalent to OCR, nor does it automatically generate editable Word, docx, or doc text. If you need to edit the contract content, you will still need to use the corresponding recognition or conversion function.
Summary: Making Scanned PDFs Go from "Barely Readable" to "Suitable for Office Use"
Scanned contract PDFs that are gray and have unclear text don't necessarily require manual retouching page by page. Using HeSoft Doc Batch Tool , you can select "Sharpen Text on PDF Images" in the PDF Tools, batch import multiple PDFs, and then uniformly optimize the page effect through "Text Clarity (Binarization)." After processing, the gray background will be significantly reduced, black text will be more prominent, and the files will be better suited for reading, printing, archiving, and subsequent recognition.
If you currently have a batch of scanned contracts, archival documents, or receipt PDFs that need organizing, it is recommended to back up the original files first, then import a few sample files to test the clarity parameters. Once you are satisfied with the results, proceed with batch processing for the entire folder. This way, you can ensure file quality while condensing repetitive operations into a single configuration, greatly enhancing office efficiency.