go-thumbnails

Pure Go thumbnail generator for PDF, TIFF, JPEG, PNG, and GIF documents. Uses PDFium via WebAssembly — no CGo required.

Features

• Multi-page composite thumbnails (up to 4 pages side-by-side with "+" indicator)
• Uniform fixed-size thumbnails with page-count badge
• Per-page thumbnail extraction via page-level API
• Error placeholder generation with colour-coded labels
• PDF rendering corruption detection

Installation

Library

go get github.com/drummonds/go-thumbnails

CLI

go install github.com/drummonds/go-thumbnails/cmd/thumbnails@latest

Usage

Library

import thumbnails "github.com/drummonds/go-thumbnails"

// Composite thumbnail (default)
img, err := thumbnails.Generate("doc.pdf", 128)

// Uniform style with page-count badge
img, err := thumbnails.GenerateStyled("doc.pdf", 128, thumbnails.StyleUniform)

// Generate and save to disk
err := thumbnails.GenerateAndSave("doc.pdf", "doc.tn_128.png", 128)

// Render individual pages
pages, err := thumbnails.RenderPages("doc.pdf")
for _, p := range pages {
    resized := thumbnails.ResizePage(p.Image, 128)
    // p.PageNum, p.PageCount available
}

// Render a single page
page, err := thumbnails.RenderPage("doc.pdf", 3)

CLI

thumbnails [flags] file [file...]

Flags:
  -w int        Thumbnail width (default 128)
  -o string     Output path or directory (default: alongside input)
  -style string Rendering style: composite, uniform, or page (default "composite")
  -page int     Page number for -style page (0 = all pages)

Examples:

# Composite thumbnail at default width
thumbnails doc.pdf

# Uniform style, 256px wide
thumbnails -w 256 -style uniform doc.pdf

# Extract all pages as individual thumbnails
thumbnails -style page doc.pdf

# Extract page 3 only
thumbnails -style page -page 3 doc.pdf

# Process multiple files
thumbnails -w 64 *.pdf

Supported formats

Format	Multi-page	Notes
PDF	Yes	Via PDFium WebAssembly
TIFF	First page only	golang.org/x/image/tiff lacks DecodeAll
JPEG	No	Simple resize
PNG	No	Simple resize
GIF	No	Simple resize

Links

Documentation	https://h3-go-thumbnails.statichost.page/
Source (Codeberg)	https://codeberg.org/hum3/go-thumbnails
Mirror (GitHub)	https://github.com/drummonds/go-thumbnails