Aludel.DocumentConverter (aludel v0.7.0)

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Converts documents between formats for LLM consumption.

Currently supports PDF to PNG conversion for the first page. The default adapter bounds the source and result sizes, conversion duration, diagnostic output, and ImageMagick resources.

Usage

PDF-to-image conversion is used for:

  • OpenAI: Chat API only supports images (PDFs work in Assistants API)
  • Ollama: Vision models require image formats

Native PDF support:

  • Anthropic Claude 4.5+: Supports PDFs via document API

Requirements

Requires ImageMagick to be installed:

  • macOS: brew install imagemagick
  • Ubuntu/Debian: apt-get install imagemagick
  • Docker: Install in runtime image

Configuration

The conversion adapter can be configured in config files:

config :aludel, :document_converter,
  adapter: Aludel.Interfaces.DocumentConverter.Adapters.Imagemagick,
  density: 150,
  timeout_ms: 30_000,
  max_input_bytes: 10_485_760,
  max_output_bytes: 20_971_520,
  max_diagnostic_bytes: 16_384

density accepts values from 72 through 300. Size and diagnostic limits can be lowered from their defaults, while timeout_ms accepts 100 through 60,000. An explicit :executable path and an existing :temporary_directory can also be supplied by trusted application configuration.

For testing, use a stub adapter.

Summary

Types

convert_result()
document()

Functions

pdf_to_image(doc)

Converts a PDF document to PNG format.

Types

convert_result()

@type convert_result() :: {:ok, document()} | {:error, term()}

document()

@type document() :: %{data: binary(), content_type: String.t()}

Functions

pdf_to_image(doc)

@spec pdf_to_image(document()) :: convert_result()

Converts a PDF document to PNG format.

Only converts the first page at 150 DPI for optimal text readability. Creates temporary files for conversion and cleans them up afterwards.

Examples

iex> pdf_doc = %{data: pdf_binary, content_type: "application/pdf"}
iex> {:ok, png_doc} = DocumentConverter.pdf_to_image(pdf_doc)
iex> png_doc.content_type
"image/png"

iex> image_doc = %{data: png_binary, content_type: "image/png"}
iex> {:ok, ^image_doc} = DocumentConverter.pdf_to_image(image_doc)
:ok