You can access the tool at: https://yutingzhang.github.io/doc-bg-remover/

This tool allows you to upload (or drag-and-drop) an image or PDF file, then modify the background, transparency, gamma, and other settings. It can convert images (or the first page of a PDF) to either grayscale or preserve original colors, optionally applying a binarization process, adjusting a white scale threshold, or controlling transparency.

Features

• Image/PDF Upload
  • Supports JPG, PNG, or PDF (first page only).
  • File selection or drag-and-drop.
• PDF Render DPI
  • For PDF input only, you can specify a DPI (dots per inch) value from 72 to 600.
  • Preset buttons (72, 150, 300, 600) for quick selection.
  • Automatically re-renders the PDF at the specified resolution.
• Binarization
  • Optional black/white conversion based on a threshold slider (0–255).
  • If binarized, images become strictly black and white (with optional transparent background).
• White Scale & Gamma Correction (if not binarizing)
  • White Scale (0–255): A linear pre-gamma adjustment to push off-white pixels closer to full white. cnew=min⁡(ct×255,255)c_{\text{new}} = \min\bigl(\tfrac{c}{t} \times 255, 255\bigr)cnew=min(tc×255,255) where ttt is the selected scale, and ccc is the grayscale value.
  • Gamma Correction (0.1–3.0): Post-scaling gamma to brighten/darken midtones.
• Background Options
  • Transparent: For grayscale modes, black pixels are fully opaque and white is fully transparent.
  • White: Produces a fully opaque PNG with white or black/colored areas, no transparency channel.
• Output Types
  • Grayscale: Convert everything to grayscale (with optional transparency if background is transparent).
  • Preserve Colors: Keep original colors and only adjust transparency or produce a fully opaque white background.
• Download Result
  • After applying all settings, you can preview the final PNG and download it.