PDFBox adding white spaces within words

Question

When I try to extract text from my PDF files, it seems to insert white spaces between severl words randomly.

I am using pdfbox-app-1.6.0.jar (latest version) on fol

Answer 1

The class org.apache.pdfbox.util.PDFTextStripper (pdfbox-1.7.1) allows to modify the propensity to decide if two strings are part of the same word or not.

Increasing spacingTolerance will reduce the number of inserted spaces.

/**
 * Set the space width-based tolerance value that is used
 * to estimate where spaces in text should be added.  Note that the
 * default value for this has been determined from trial and error.
 * Setting this value larger will reduce the number of spaces added. 
 * 
 * @param spacingToleranceValue tolerance / scaling factor to use
 */
public void setSpacingTolerance(float spacingToleranceValue) {
    this.spacingTolerance = spacingToleranceValue;
}

Answer 2

Unfortunately there is currently no easy solution for this.

Internally PDF documents simply contain instructions like "place characters 'abc' in position X" and "place characters 'def' in position Y", and PDFBox tries to reason whether the resulting extracted text should be "abc def" or "abcdef" based on things like the distance between X and Y. These heuristics are generally pretty accurate, but as you can see they don't always produce the correct result.

One way to improve the quality of the extracted text is to try a dictionary lookup on each extracted word or token. If the lookup fails, try combining the token with the next one. If a dictionary lookup on the combined token succeeds, then it's fairly likely that the text extractor has mistakenly added an extra space inside the word. Unfortunately such a feature does not yet exist in PDFBox. See https://issues.apache.org/jira/browse/PDFBOX-1153 for the feature request filed for this. Patches welcome!