PDF

The Pdf tag displays a PDF document in the labeling interface. You can use this tag to:

• Perform document-level annotations such as classification, transcription, and summarization.
• Perform OCR validation on supported PDFs.

Supports:

• Zoom
• Rotation
• PDFs up to 100 pages

Use with the following data types: PDF.

Parameters

Param	Type	Description
value	string	Data field value containing the URL to the PDF

Example: PDF classification

Labeling configuration apply document-level classification to PDF documents:

<View>
  <Pdf name="pdf" value="$pdf" />
  <Choices name="choices" toName="pdf">
    <Choice value="Legal" />
    <Choice value="Financial" />
    <Choice value="Technical" />
  </Choices>
</View>

Example Input data:

{
  "pdf": "https://app.humansignal.com/static/samples/opossum-cuteness.pdf"
}

Example: OCR

Labeling configuration for PDFs:

<View>
  <OcrLabels name="ocr" toName="pdf">
    <Label value="Typo"/>
    <Label value="Incorrect amount"/>
    <Label value="Incorrect name"/>
  </OcrLabels>

  <Pdf name="pdf" value="$pdf"/>
</View>

Example Input data:

{
  "pdf": "https://app.humansignal.com/static/samples/opossum-cuteness.pdf"
}

OcrLabels

This tag adds bounding boxes to the PDF and allows you to assign labels to them.

This tag must have one or more Label tag children, and supports standard parameters such as maxUsages (see RectangleLabels as an example).

Supported PDFs

PDFs that work best with the new OCR labeling are those that already contain a selectable text layer (text overlay).

In these PDFs, when you draw a bounding box, the tool can read and highlight the underlying text from that layer (see the video below).

Image-only PDFs such as scans or phone photos without a text layer won’t return text. For those, you may need to use an external OCR tool to add a text layer first. If a PDF’s text layer is misaligned or low quality, captured text may be incomplete or incorrect, and this feature can help you audit and improve those overlays.

Results:

Result	Type	Description
x, y, width, height	Number	Numbers from 0 to 1 that are relative to the page dimensions.
rotation	Number	Number in degrees clockwise from 0–360. Rotation is calculated with the origin at (x, y) (the top-left corner of the region).
pageIndex	Number	Page number, 1-based.
ocrtext	String	Captured text. This can be edited by selecting the region and then editing the text from the Info panel.