There is currently no easy way to retrieve accurate line size metrics using Tesseract.js. Several sub-optimal ways of accomplishing this are listed below.

• Use word object within blocks output format.
  • These metrics are rarely accurate, and unhelpful without additional information
    • There is no absolute mapping between font size and pixels
• Use ascender/descender/x_size metrics in hocr output
  • These are useful and accurate (at least using Tesseract Legacy)
  • Unfortunately, getting the values is a hassle
    • Extracting requires using an XML parser or regular expressions
• Calculate font size manually using character-level bounding boxes
  • This works, but is even more of a hassle than parsing from HOCR

The ascender/descender/row_height metrics from the hocr output should be added to the blocks output format. This will allow for easily retrieving accurate data about line size.