Rescan Symbols rebuilds the current symbol setup. Use embedded PDF data when it is available, or scan the chart images when the file contains no readable symbol information.

Running either option replaces all existing symbols. Review the chosen tab and its action button carefully before you continue.

Option 1: Import Symbols from the PDF

Scan PDF File tab showing a High Quality result and Import PDF Symbols button

Select Scan PDF File to use symbol information embedded in the original PDF. The badge describes the best source the app found:

Understanding PDF Data Quality

High quality
The symbols were available as clean text-based characters. This usually gives the strongest automatic result, but you should still review the imported list.
Medium quality
The symbols were stored as small images. Some symbols may need adding or merging after import.
Low quality
The symbols were extracted from drawing paths or graphics. Check carefully for duplicates and incorrect symbols; manual setup may be quicker for a poor result.
Mixed quality
Some pages contained usable PDF symbol data and others did not. The app keeps the extracted symbols and image-scans the remaining pages, then tries to match their populated grid squares.
Not checked
The PDF has not yet been checked, or an earlier scan was interrupted. Select Import PDF Symbols to run the check.
Manual setup needed
No readable symbol data was found. This is normal for photographs and some PDFs. Switch to Scan Page Images.

The green check mark on a tab shows which source is currently applied to the project. Select Import PDF Symbols to run the PDF import again.

Option 2: Scan the Page Images

Scan Page Images tab with contrast threshold slider and Run New Scan button

Image scanning does not identify individual symbols. It examines the chart image and decides which grid squares look populated. You then tap those grid squares on Set Symbols to create and match the symbols yourself.

  • Lower percentage: marks fewer grid squares as populated. Use this for a noisy or unclear chart so fewer blank grid squares need removing in Erase Mode.
  • Higher percentage: marks more grid squares as populated. Use this when faint symbols are being missed.
  • At or near 100%: even blank or noisy grid squares may be treated as populated, which can make the whole chart appear filled.
  • Too low: genuine symbols may be missed.

Adjust the threshold, then select Run New Scan. Review the result and use Erase Mode to remove grid squares that are not stitches.

Recovering After Delete All Symbols

If you removed all symbols by mistake, open Configure Symbol Setup and rescan. A high-quality PDF import may rebuild most or all of the original symbol list. Medium- and low-quality files usually need more checking, merging and manual correction. For a photograph or a file with no embedded symbol data, scan the page images and rebuild the individual symbols manually.

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