Page Selection

Overview

By default, PDF4LLM processes every page in a document. The pages parameter lets you specify exactly which pages to extract — as a List<int> of zero-based page indices. It is supported by ToMarkdown(), ToJson(), and ToText().

using PDF4LLM;

// Extract only the first three pages
string mdText = PdfExtractor.ToMarkdown("document.pdf", pages: new List<int> { 0, 1, 2 });

Zero-based indexing

Page numbers in PDF4LLM are zero-based — the first page of a document is page 0, the second is page 1, and so on.

Document page	`pages` index
Page 1	`0`
Page 2	`1`
Page 10	`9`
Last page	`n - 1`

Passing a page index that doesn’t exist in the document will raise an exception. Always check the document’s page count (doc.PageCount) before constructing a dynamic page list.

Common patterns

First N pages

int n       = 5;
var pages   = Enumerable.Range(0, n).ToList();
string mdText = PdfExtractor.ToMarkdown("document.pdf", pages: pages);

Last N pages

using MuPDF.NET;

Document doc       = new Document("document.pdf");
int      pageCount = doc.PageCount;

var lastFive = Enumerable.Range(pageCount - 5, 5).ToList();
string mdText = PdfExtractor.ToMarkdown(doc, pages: lastFive);

doc.Close();

A specific range

// Pages 10–19 (zero-based)
var pages   = Enumerable.Range(10, 10).ToList();
string mdText = PdfExtractor.ToMarkdown("document.pdf", pages: pages);

Non-contiguous pages

// Cover page, table of contents, and appendix
string mdText = PdfExtractor.ToMarkdown(
    "document.pdf",
    pages: new List<int> { 0, 1, 47, 48, 49 }
);

Every other page

// Even pages only (0, 2, 4, ...)
var evenPages = Enumerable.Range(0, 50)
                          .Where(i => i % 2 == 0)
                          .ToList();

string mdText = PdfExtractor.ToMarkdown("document.pdf", pages: evenPages);

Getting the page count

Open a Document to inspect the page count before building your pages list:

using MuPDF.NET;
using PDF4LLM;

Document doc       = new Document("document.pdf");
int      pageCount = doc.PageCount;

Console.WriteLine($"Total pages: {pageCount}");

// Extract the second half of the document
int midpoint = pageCount / 2;
var pages    = Enumerable.Range(midpoint, pageCount - midpoint).ToList();

string mdText = PdfExtractor.ToMarkdown(doc, pages: pages);
doc.Close();

Page selection with per-page chunks

When using LlamaMarkdownReader, the returned list will only contain chunks for the pages you specify if you pre-filter the results. Each chunk’s ExtraInfo preserves the original page number from the document:

using PDF4LLM;

var reader    = PdfExtractor.LlamaMarkdownReader();
var allChunks = reader.LoadData("document.pdf");

// Filter to pages 4, 5, and 6 after loading
var chunks = allChunks
    .Where(c => new[] { 4, 5, 6 }.Contains((int)c.ExtraInfo["page"]))
    .ToList();

foreach (var chunk in chunks)
{
    int page = (int)chunk.ExtraInfo["page"];
    Console.WriteLine($"Page {page}: {chunk.Text.Length} chars");
}
// Page 4: 1842 chars
// Page 5: 2103 chars
// Page 6: 987 chars

The page value in ExtraInfo reflects the original document page number, not the position in the returned list. Page 4 in the document is always reported as 4, regardless of how many pages were skipped.

Page selection with ToJson() and ToText()

The pages parameter works identically across all three extraction methods:

// JSON output — specific pages only
string json = PdfExtractor.ToJson("document.pdf", pages: new List<int> { 0, 1, 2 });

// Plain text — specific pages only
string text = PdfExtractor.ToText("document.pdf", pages: new List<int> { 0, 1, 2 });

Processing a document in batches

For very large documents, process pages in batches to manage memory usage:

using MuPDF.NET;
using PDF4LLM;
using System.IO;

Document doc       = new Document("large-document.pdf");
int      batchSize = 20;
var      results   = new List<string>();

for (int start = 0; start < doc.PageCount; start += batchSize)
{
    int count = Math.Min(batchSize, doc.PageCount - start);
    var batch = Enumerable.Range(start, count).ToList();

    Console.WriteLine($"Processing pages {batch.First()}–{batch.Last()}...");

    string chunk = PdfExtractor.ToMarkdown(doc, pages: batch);
    results.Add(chunk);
}

doc.Close();

string fullText = string.Join("\n\n", results);
File.WriteAllText("output.md", fullText, System.Text.Encoding.UTF8);

Console.WriteLine($"Done. {doc.PageCount} pages processed.");

Skipping blank or cover pages

Combine page selection with a quick content check to skip pages that return no meaningful text:

using MuPDF.NET;
using PDF4LLM;

Document doc      = new Document("document.pdf");
var      nonBlank = new List<int>();

for (int i = 0; i < doc.PageCount; i++)
{
    // Quick native probe — fast, no OCR
    string native = PdfExtractor.ToText(doc, pages: new List<int> { i });
    if (native.Trim().Length > 0)
        nonBlank.Add(i);
}

Console.WriteLine($"{nonBlank.Count} of {doc.PageCount} pages contain text");

string mdText = PdfExtractor.ToMarkdown(doc, pages: nonBlank);
doc.Close();

The pages parameter is supported by ToMarkdown(), ToJson(), and ToText(). For full API signatures see the API reference.

Next steps

Saving Output

Write extracted pages to .md, .json, and .txt files.

Extract Markdown

Full walkthrough of ToMarkdown() with all common options.

Extract JSON

Bounding boxes and layout data for custom pipelines.

OCR

Process scanned pages with Tesseract OCR.

Getting Started

Guides

Integrations

Reference

Overview

Zero-based indexing

Common patterns

First N pages

Last N pages

A specific range

Non-contiguous pages

Every other page

Getting the page count

Page selection with per-page chunks

Page selection with ToJson() and ToText()

Processing a document in batches

Skipping blank or cover pages

Next steps

Saving Output

Extract Markdown

Extract JSON

OCR

​Overview

​Zero-based indexing

​Common patterns

​First N pages

​Last N pages

​A specific range

​Non-contiguous pages

​Every other page

​Getting the page count

​Page selection with per-page chunks

​Page selection with ToJson() and ToText()

​Processing a document in batches

​Skipping blank or cover pages

​Next steps

Saving Output

Extract Markdown

Extract JSON

OCR

Overview

Zero-based indexing

Common patterns

First N pages

Last N pages

A specific range

Non-contiguous pages

Every other page

Getting the page count

Page selection with per-page chunks

Page selection with ToJson() and ToText()

Processing a document in batches

Skipping blank or cover pages

Next steps