How Conversion Works

Each converter reconstructs Markdown structure from the source format's own layout signals.

PDF

lopdf only reads PDF objects and decompresses streams. The rest is done here from glyph coordinates:

• Fonts are decoded through /ToUnicode, /Encoding + /Differences, the embedded Type 1 / CFF font's own encoding, predefined CJK CMaps and Adobe-Japan1 CIDs, so Japanese PDFs without /ToUnicode still extract.
• Glyphs become words (by gaps measured against font size) and lines. Reading order comes from an XY-cut, so multi-column pages read column by column.
• Tables are detected from drawn rules (merged cells included) or, for borderless tables, from aligned whitespace columns.
• Headings come from relative font size, lists from bullet and number markers, code from monospaced fonts, links from annotations and contents pages from dot leaders.
• Repeated running headers, footers and page numbers are removed.

Others

• Word / PowerPoint: parsed directly from OOXML (document.xml, slideN.xml): headings, bold/italic, hyperlinks, list nesting, tables. No Office shell-out.
• Excel: each sheet is split into blocks by blank rows, then each block is classified as table or free text.