Feature Request: Save embedded images from PDFs as separate files with relative Markdown links

Problem

When converting PDFs with embedded images to Markdown, markitdown currently either:

• Truncates base64 data (showing ![](data:image/png;base64...)), or
• Preserves full base64 inline (which makes the Markdown file very large and unsuitable for RAG/indexing)

For full-context RAG pipelines and document archival, I need:

1. Embedded images extracted and saved as separate files (e.g. images/page3-figure1.png)
2. Markdown references using relative paths: ![description](images/page3-figure1.png)
3. Optional: image metadata/captions in front matter or inline comments

Use case

• Converting technical documentation, datasheets, and PDFs with diagrams for AI/LLM ingestion
• Preserving full document context including visual information
• Keeping Markdown files lightweight and portable while still referencing images

Proposed behavior

Add a CLI flag and Python API option, for example:

markitdown document.pdf --extract-images --output-dir ./output

from markitdown import MarkItDown
md = MarkItDown(extract_images=True, output_dir="./output")
result = md.convert("document.pdf")
# result.markdown includes: 
# Actual image files saved to ./output/images/

Alternatives considered

• Full base64 inline: makes files too large for indexing/LLM pipelines
• Image descriptions only: loses visual context for diagrams, charts, schematics
• Manual extraction: error-prone and not reproducible

Additional context

• Related to issue #162 (closed) and PR #1140 (base64 preservation added)
• Complements issue #1346 (LLM image descriptions for RAG)
• Would benefit users working with schematics, datasheets, research papers, and technical documentation

Environment

• markitdown version: 0.1.6
• Python version: 3.11+
• OS: macOS

Start at the MarkItDown constructor and the convert("document.pdf") entry point shown in the issue, then trace the PDF conversion path and the CLI command. Done means both interfaces support the requested image output directory and produce Markdown with relative links to extracted image files.