pdf-fox

PDF to PNG converter for Node.js, powered by PDF.js and @napi-rs/canvas.

日本語

Install

npm install pdf-fox

CLI

# Convert all pages → 1.png, 2.png, ... next to the input
npx pdf-fox input.pdf

# Specify output directory → output/1.png, output/2.png, ...
npx pdf-fox input.pdf -o output/

# Convert a specific page → 2.png
npx pdf-fox input.pdf -p 2

# Save a single page to an explicit file
npx pdf-fox input.pdf -p 1 -o cover.png

# Set resolution (default: 200 DPI)
npx pdf-fox input.pdf --dpi 300

Options:
  -o, --output <path>       Output directory or file path
  -p, --page <number>       Page number to convert (default: all pages)
  -r, --dpi <number>        Resolution in DPI (default: 200)
  -b, --background <color>  Background color (default: white)
  -f, --font <name=path>    Substitute font for a non-embedded font (repeatable)
      --no-system-fonts     Disable automatic CJK system-font fallback
      --bold <px>           Thicken text by this width in px (e.g. 0.6; default: 0)
  -h, --help                Show help
  -V, --version             Show version

Text looks too thin?

PDF.js renders glyph outlines faithfully, so text can look lighter than in a browser, which applies extra font smoothing on macOS. Thicken it with --bold (or the stemDarkening option), e.g. --bold 0.6.

Non-embedded fonts

If a PDF references a font without embedding it, those glyphs would render as blank boxes. By default pdf-fox points the generic serif/sans-serif families at an available CJK system font (Hiragino, Yu, MS, Noto, …), so such text renders out of the box — just like Firefox falling back to system fonts. Disable this with --no-system-fonts for output that doesn't depend on installed fonts.

To use a specific font (e.g. when the system has none, or to match the original exactly), supply a local font file under the name the PDF uses:

npx pdf-fox input.pdf -f "MSMincho=~/Library/Fonts/msmincho.ttc"

The name (MSMincho) is the PDF's font name without its subset prefix (the part before +). You can inspect font names with pdffonts input.pdf.

Library

import { convertPdfToPng, convertPdfPageToPng } from "pdf-fox";
import { readFileSync } from "fs";

const pdf = readFileSync("input.pdf");

// All pages
const pages = await convertPdfToPng(pdf);
// => [{ pageNumber: 1, data: Buffer, width: number, height: number }, ...]

// Specific page
const page = await convertPdfPageToPng(pdf, 1, { scale: 2.0 });

// Substitute a non-embedded font
const rendered = await convertPdfToPng(pdf, {
  fonts: { MSMincho: "/path/to/msmincho.ttc" },
});

Options

| Option | Type | Default | Description | |---|---|---|---| | scale | number | 1.5 | Rendering scale (1.0 = 72 DPI) | | background | string | "white" | Background color (any CSS color string) | | fonts | Record<string, string> | {} | Substitute fonts for non-embedded fonts, mapping the PDF's font name to a local font file path | | systemFontFallback | boolean | true | Point serif/sans-serif at an available CJK system font so non-embedded CJK text renders. Disable for font-independent output | | stemDarkening | number | 0 | Thicken text by stroking glyph outlines with this width in output pixels, approximating browser font smoothing. 0 disables; try 0.5–1.0 |

Requirements

• Node.js 18+