Why Is a Scanned PDF Smaller Than the Same File in Photoshop?
Question details
The user is experiencing a massive file size increase when opening a 9 MB scanned PDF in Photoshop and saving it, resulting in a 900 MB file.
- Product
- Device & OS
- not provided
- Scenario
- Importing a scanned PDF document into Photoshop and exporting/saving it back to a local drive.
- Observed behavior
- The PDF file size inflates from 9 MB to approximately 900 MB because Photoshop expands the page into an uncompressed raster image and saves it without compression.
Before adjusting your export settings, it is important to understand that Photoshop is an image editor that rasterizes PDF pages into pixel data, which inherently changes how the document is compressed.
Re-enable Compression When Saving from Photoshop
Use proper Adobe PDF preset and compression settings during the save process to prevent file size inflation.
When a scanner creates a PDF, it typically applies highly efficient image compression directly to the scanned document. However, when you open that PDF in Photoshop, the software rasterizes the page into uncompressed pixel data. If you save the file from Photoshop with compression disabled, the resulting file retains all that uncompressed data, causing the size to balloon.
To fix this, you must instruct Photoshop to re-apply compression when exporting the document back to PDF format.
In Photoshop, click on 'File' in the top menu bar, select 'Save As', and choose 'Photoshop PDF' from the format dropdown menu.
Click 'Save'. This will open the 'Save Adobe PDF' dialog box where you can manage file output settings.
Navigate to the 'Compression' tab on the left side of the dialog box. Ensure you do not disable compression.
Under 'Options', set the compression type to 'JPEG' and choose an Image Quality setting such as 'High' or 'Maximum'. This will keep the output file manageable while preserving visual fidelity.
Edit PDFs Directly Without Rasterizing Using WPS Office
Instead of opening PDFs in Photoshop and causing massive file size increases due to rasterization, use a native PDF editor. WPS Office lets you modify text, images, and pages directly without losing original compression efficiency or inflating the file size.
- 1. Open WPS Office: Launch WPS Office on your computer and select 'PDF Edit' from the main dashboard.
- 2. Import Your PDF: Open your scanned PDF file. WPS handles it natively, preventing the document from being expanded into uncompressed pixels.
- 3. Edit Natively: Use the 'Edit' tab to modify text, insert images, or add annotations directly onto the document.
- 4. Save Document: Click 'Save'. The PDF retains its compact file structure and native compression.
Frequently Asked Questions
Does opening a PDF in Photoshop reduce its visual quality?
Not necessarily, but it rasterizes the document. Any text or vector graphics will be converted to pixels based on the resolution you specify during import, which can make them look pixelated if the resolution is set too low.
How do I reduce the size of a PDF already saved from Photoshop?
You can reopen it and save it again using 'File' > 'Save As'. In the 'Save Adobe PDF' dialog, go to the Compression section. Select 'Downsample' to lower the resolution if it is unnecessarily high, and set the Compression to 'JPEG'.
Why shouldn't I use Photoshop to edit text in a PDF?
Because Photoshop rasterizes PDFs upon opening, text is converted into an image. You cannot edit the text characters directly anymore. It is better to use a dedicated PDF editor like WPS Office to modify text.
