What are the main factors to check when evaluating PDF parser effectiveness?

Scanned PDFs (Image-Based PDFs):

Test: Include a page or a full PDF that is a scanned image, not actual text. This will evaluate the parser's ability to handle OCR (Optical Character Recognition) or its integration with OCR libraries.

Purpose: Many PDFs are created from scans, and this is a critical test for real-world scenarios.

PDFs with Different Font Types and Sizes:

Test: Use a PDF with a mix of fonts, font sizes, and styles (e.g., bold, italic, underlined).

Purpose: Assess how well the parser handles font variations, which can affect text extraction accuracy and layout reconstruction.

PDFs with Embedded Images and Graphics

Test: Include PDFs with complex embedded images, vector graphics, and annotations.

Purpose: Evaluate the parser's ability to extract image data, preserve image quality, and handle annotations.

PDFs with Complex Tables:

Test: Include tables with merged cells, nested tables, tables spanning multiple pages, and tables with complex formatting.

Purpose: Test the parser's robustness in handling challenging table structures.

PDFs with Form Fields:

Test: Include a PDF with fillable form fields (e.g., text boxes, checkboxes, radio buttons).

Purpose: Evaluate the parser's ability to extract form field data and preserve field structure.

PDFs with Bookmarks and Outlines:

Test: Include PDFs with well-defined bookmarks and outlines.

Purpose: Assess the parser's ability to extract and preserve the document's logical structure.

PDFs with Metadata:

Test: Include PDFs with embedded metadata (e.g., author, title, keywords).

Purpose: Evaluate the parser's ability to extract and preserve document metadata.

PDFs with Different Compression Techniques:

Test: Include PDFs with different image compression techniques (e.g., JPEG, JPEG2000).

Purpose: Evaluate how well the parser handles various compression methods.

PDFs with Security Restrictions:

Test: Include PDFs with password protection or other security restrictions.

Purpose: Assess the parser's ability to handle encrypted or restricted PDFs.

Handling of Special Characters and Unicode:

Test: Include a PDF with a wide range of special characters and Unicode symbols.

Purpose: Evaluate the parser's ability to handle international characters and special symbols accurately.

Testing for correct reading order of the text:

Test: Create a PDF with a deliberately jumbled text order.

Purpose: Verify that the parser can correctly reconstruct the intended reading order.

Testing for correct identification of headers and footers:

Test: create a PDF with headers and footers.

Purpose: Verify that the parser can correctly identify and extract header and footer information.

Testing for correct identification of page numbers:

Test: Create a PDF with different page number styles.

Purpose: Verify that the parser can correctly identify and extract page numbers.

Testing for correct identification of lists:

Test: Create a PDF with numbered and bulleted lists.

Purpose: verify that the parser can correctly identify and extract lists.

Evaluation Metrics:

Accuracy: How accurately the parser extracts text and data.

Layout Preservation: How well the parser preserves the original document's layout.

Speed: The time it takes for the parser to process a PDF.

Memory Usage: The amount of memory the parser consumes.

Robustness: The parser's ability to handle various PDF formats and complexities.

Error Handling: How well the parser handles errors and exceptions.

Completeness: How much of the information that is present in the PDF is actually extracted.

By incorporating these tests and scenarios into your evaluation, you'll gain a more comprehensive understanding of the strengths and weaknesses of different PDF parsers.