Web tool Bazar

PDF Colour Inverter & Grayscale Converter

Choose between full colour inversion (negative) or grayscale conversion (black & white). Perfect for dark mode, printing, or accessibility. 100% private – all in your browser. Supports PDFs up to 1GB.

Negative Effect Grayscale No Upload 1GB Limit

Drag & Drop PDF Here

or click to browse (PDF only, max 1GB)

Max file size: 1GB (very large files may be slow)

Conversion Mode

Full Colour Inversion
Negative / opposite colours
Grayscale Conversion
Black & white (luminance)
Note: This tool rasterizes each page (converts text and vectors to images). The output PDF will contain images. For large files, processing may take time and require sufficient memory.

File Status

No PDF selected

100% Private

Files never leave your device.

Two Modes

Negative or grayscale – your choice.

Dark Mode Ready

Invert for night reading.

Up to 1GB

Supports large PDF files.

Free PDF Colour Inverter & Grayscale Converter

Welcome to Web tool Bazar's dual‑mode PDF processor. You can now either invert all colors (producing a negative) or convert to grayscale (black & white) any PDF document up to 1GB. Both operations run entirely in your browser – no upload, no privacy concerns.

🎯 Why Use These Modes?

  • Full Colour Inversion: Creates a negative effect. Great for dark mode reading (white backgrounds become black), artistic projects, or saving printer toner when printing dark pages.
  • Grayscale Conversion: Removes all colour, leaving a classic black‑and‑white PDF. Ideal for printing on monochrome printers, reducing file size, or creating a uniform look.

📋 Step-by-Step Guide

  1. Upload your PDF – Drag & drop, select a file (up to 1GB), or click "Try Sample PDF" to test with a generated document.
  2. Choose mode – Click either "Full Colour Inversion" or "Grayscale Conversion". The selected option will be highlighted.
  3. Click "Process PDF" – The tool renders each page, applies the chosen effect, and builds a new PDF.
  4. Download – Save your converted PDF. File will be named with "_inverted" or "_grayscale" suffix.

⚙️ Technical Details

For colour inversion, we compute the complement of each RGB channel: new R = 255 - old R, etc. For grayscale, we use the standard luminance formula: gray = 0.299*R + 0.587*G + 0.114*B to maintain perceived brightness. All pages are rasterized at 1.5x scale to preserve quality, then saved as JPEG (quality 0.9) inside a new PDF.

Large file handling: The tool can process files up to 1GB, but please note that very large PDFs may require significant memory and time. For optimal performance, ensure your device has enough RAM.

🧐 FAQ

Will the output be searchable?

No, text becomes part of an image. If you need searchable text, this tool is not suitable.

Can I choose a different quality?

We use a fixed high quality (0.9) to preserve details. You can compress the output later with our Compress PDF tool.

Is it really private?

Absolutely. All code runs locally; no data is sent to any server.

What does the sample PDF contain?

A 2‑page PDF with colorful shapes and text: page 1 has a red rectangle and green text; page 2 has a blue circle on a yellow background. Perfect for testing both modes.

Last updated: March 2026 | Words: ~1000