Invert PDF Colors
Make any PDF easier on the eyes at night. Invert it into white-on-black, use a dark mode that keeps colors recognisable, or pick a warm night sepia or your own background and text colors, then download a new dark PDF that works in every reader and e-reader.
Pages are converted to images, so text is not selectable in the new PDF.
How to use the Invert PDF Colors
- Open a PDF with the Choose PDF button or drag it onto the drop area.
- Pick a style: Invert, Dark mode (keeps colors), Night sepia, Dark gray or Custom with your own two colors.
- Check the preview and use the arrows to look at other pages.
- Choose the resolution: 150 DPI suits screens and tablets; use 200–300 DPI for small print.
- Press Convert, wait for the pages to finish and download the dark PDF.
How each style changes the colors
Every page is rendered exactly as a PDF reader shows it, then each pixel's red, green and blue values (0–255) are transformed:
| Style | Formula | White paper | Black text | Red (220, 40, 40) |
|---|---|---|---|---|
| Invert | c′ = 255 − c | black | white | cyan (35, 215, 215) |
| Dark mode | c′ = c + 255 − max − min | black | white | red (215, 35, 35) |
| Night sepia / Dark gray / Custom | t = 1 − Y/255, color = bg + (text − bg) × t | background color | text color | a tone between the two |
Dark mode flips the lightness of each color while keeping its hue and saturation, the same idea as the "smart invert" accessibility setting on phones. The themed styles first compute brightness with the luminance formula Y = 0.299 R + 0.587 G + 0.114 B and then blend between your background and text colors, so every page uses just those two tones. Soften contrast moves both ends toward mid-gray, which reduces glare from bright white text.
Which style to choose
- Invert: plain black-and-white documents, code listings and scanned text. Maximum contrast.
- Dark mode: slides, charts, highlighted notes and anything where colors carry meaning.
- Night sepia: long reading sessions before bed; warm tones and softer contrast.
- Dark gray: a neutral, less harsh alternative to pure black backgrounds, good on OLED tablets.
- Custom: match your e-reader theme, or try light text on navy or dark green.
Photos are inverted too and will look like negatives in Invert mode; Dark mode keeps them recognisable but still flips light and dark areas.
Resolution and file size
A4 at 150 DPI is 1240 × 1754 pixels per page, which looks sharp on most tablets and laptops. Choose 200 DPI for small print or high-density screens, or 100 DPI for the smallest file. Dark pages compress well as JPEG, but a text-only PDF will still grow because each page becomes an image. For printing, use the original or Grayscale PDF; to invert a single picture, use Invert Image Colors.
Frequently asked questions
How do I invert the colors of a PDF?
Open the PDF here, keep the Invert style and press Convert. Every page is rendered, each pixel's red, green and blue values are replaced by 255 minus the value, and the pages are saved into a new PDF that you can download and open in any reader.
What is the difference between Invert and Dark mode?
Invert turns every color into its opposite, so white becomes black but red also becomes cyan and photos look like negatives. Dark mode flips only the lightness and keeps the hue: white paper becomes black, black text becomes white, and a red heading stays red. Use Dark mode for documents with colored charts or highlights.
Is dark mode really easier on the eyes?
Many people find light text on a dark background more comfortable in a dim room because the screen emits less light overall. In bright surroundings dark text on a light background is usually easier to read. Night sepia is a middle ground with warm, softer contrast.
Can I still select and search the text?
No. To guarantee the colors look the same in every reader, each page is converted into an image, so text can no longer be selected or searched. Keep the original PDF for copying text, or run the result through OCR.
Why is the dark PDF larger than the original?
Text PDFs store letters as small vector instructions, while the converted file stores a picture of every page. Lower the resolution to 100–150 DPI or reduce the JPEG quality for a smaller file, or compress it afterwards.
Will printing the inverted PDF use a lot of ink?
Yes. A dark background covers the whole page with ink or toner, so inverted PDFs are meant for screens, tablets and e-readers. Print the original instead, or use the Grayscale PDF tool if you want to save color ink.