1. Do a color selection on the text (using black of course). This selects the text, and the table
   
2. Select>To path. This creates a path where each "stroke" encloses an area of white or black
   
3. When you look at your page, the areas inside the strokes generated by the grid are much larger than the areas of the strokes generated by the text.
   
4. Enters the script, that can filter strokes on various size criteria, one of them being area.
   
5. Your text is about 50px high, so if you filter on an area that is 2500 pixels-square, you eliminate the strokes from the text, and only keep the ones from the grid.
   
6. The script creates a new path with the small strokes removed. In the Path list, right click on it and Path to selection. This should create a selection on the table only.
   
7. Select>Grow that selection by one pixel
   
8. Bucket-fill with white
   

• Get ofn-remove-grid from here (warning: not the same location as the other script) and install as indicated at the bottom of the page.
  
• The script is reached by Filters>Enhance>Remove table/grid around text
  
• The script works as above:
  • Does a color selection (uses the foreground color)
    
  • Creates a path from the selection
    
  • Removes the areas below a given size from that path
    
  • Creates a selection from the result
    
  • Bucket-fills the selection with the background color.
    
• The parameters:
  • Grow selection before: amount to grow the selection after the color selection. Can be used to compensate for small discontinuities in the grid. Don't push that too much as it can make large blocks of letters contiguous and bigger than your smaller grid rectangle.
    
  • Area threshold: the area under which the selection parts are removed. A good way to estimate: slightly smaller than  the smallest rectangle in your grid (the 1.01 in yours). How to find out:
    • Make a rectangle selection slightly inside this area
      
    • Open the histogram (Windows>Dockable dialogs>Histogram) and look a the Pixels value which is the number of pixels included in the selection (about 18000 in your image)
      
  • Grow selection After: amount to grow the selection before the bucket fill. Add a 1 or 2 pixels to cover pixels that may be missed d to path inaccuracies.
    

(10-02-2020, 08:38 AM)rich2005 Wrote: The ofn-remove-grid.py plugin works really well.  It answers the topic question on removing that table. Using a more usual scan, greyscale 300 ppi



1. Scan straight into Gimp. Not great, uneven colour, slightly skewed. A typical scan.
2. Apply levels to get even colour
3. A bit faint so apply threshold to get more contrast
4. Apply the plugin, (grow selection = 1) and the dividing lines gone. A few speckles 
5. Export that to a png and run through Tesseract - text is recognised
but
6. Run the original scan through Tesseract and get a better result. Tesseract ignores the lines.

I am gradually adding to my kubuntu 20.04 desktop, I think I will give Tesseract 5 a go, see if YAGF works with that version. There are PPA's for Tesseract.