PDF Grayscale Converter
Choose a color PDF and download a grayscale copy. Every page is redrawn as a gray picture, so text in the result is an image and can no longer be selected or searched.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose or drop a PDF.
- Pick the resolution and the JPEG quality.
- Press Convert and download. The progress line shows the page being drawn. The file is named
name-grayscale.pdf.
How it works
Every page is rendered to a canvas with pdf.js at the chosen DPI (72 points per inch), each pixel is replaced by its gray value, the page is encoded as a JPEG and placed on a new page of the original size with pdf-lib.
Example
A pure red pixel (255, 0, 0) becomes gray 76, a pure green one (0, 255, 0) becomes 150, a pure blue one (0, 0, 255) becomes 29, and white stays 255.
Tips
- Keep the original for editing; use the grayscale copy only for printing.
- If the result is too large, lower the DPI or the quality and convert again.
Frequently asked questions
Does the text stay selectable?
No. The tool draws every page with pdf.js and stores it as a gray JPEG image, so the text becomes part of the picture. Keep your original if you need to search or copy from it.
Why can the file be bigger than the original?
A text PDF is small because letters are stored as shapes, while a picture holds every pixel. A higher DPI and High quality make the file bigger; 100 DPI with Medium quality makes it smaller.
Which DPI should I choose?
As a rule of thumb, 150 DPI is fine for reading and ordinary office printing. Choose 200 DPI for small print or line drawings, and 100 DPI for a quick draft.
Is the page size kept?
Yes. Each page keeps its displayed size in points; only the sharpness depends on the DPI. Very large pages are drawn at a lower DPI so that the browser does not run out of memory.
How are colors turned gray?
Each pixel gets the gray value 0.299 R + 0.587 G + 0.114 B, the standard weights for how bright each color looks to the eye.