If the software exporting the PDF couldn't correctly embed the original font (like Arial Bold or Times New Roman ), it might create a generic CIDFont substitute to keep the document readable—or at least try to.
The most frequent issue occurs when a PDF is opened in a viewer that cannot find or recreate the original font. cidfont f1
If you encountered this in a dataset like Open Images, cidfont might refer to the class ID for "Font" or a truncated label for a specific hierarchical tag. If the software exporting the PDF couldn't correctly
This format allows for efficient handling of massive character sets (up to 65,535 characters) that standard 8-bit fonts cannot accommodate. Common Issues with CIDFont F1 This format allows for efficient handling of massive
When software like InDesign or online PDF converters export a file, they may assign generic internal names like F1 , F2 , or F3 to the embedded font subsets.
Researchers often inspect F1 scores per Class ID ( cid ) to diagnose model failure on rare classes.