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Document Layout Analysis - IPageSegmenter, Docstrum

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- Create a TextBlock class
- Creates IPageSegmenter
- Add other useful distances: angle, etc.
- Update RecursiveXYCut
 - With IPageSegmenter and TextBlock
 - Make XYNode and XYLeaf internal
- Optimise (faster) NearestNeighbourWordExtractor and isolate the clustering algorithms for use outside of this class
- Implement a Docstrum inspired page segmentation algorithm
This commit is contained in:
BobLd
2019-08-10 16:01:27 +01:00
parent 2d6e49426a
commit eb9a9fd00e
10 changed files with 544 additions and 119 deletions
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42
src/UglyToad.PdfPig/DocumentLayoutAnalysis/RecursiveXYCut.cs
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@@ -11,14 +11,31 @@ namespace UglyToad.PdfPig.DocumentLayoutAnalysis
/// https://en.wikipedia.org/wiki/Recursive_X-Y_cut
/// <para>See 'Recursive X-Y Cut using Bounding Boxes of Connected Components' by Jaekyu Ha, Robert M.Haralick and Ihsin T. Phillips</para>
/// </summary>
public static class RecursiveXYCut
public class RecursiveXYCut : IPageSegmenter
{
/// <summary>
/// Create an instance of Recursive X-Y Cut page segmenter, <see cref="RecursiveXYCut"/>.
/// </summary>
public static RecursiveXYCut Instance { get; } = new RecursiveXYCut();
/// <summary>
/// Get the blocks.
/// <para>Uses 'minimumWidth' = 0, 'dominantFontWidthFunc' = Mode(Width), 'dominantFontHeightFunc' = 1.5 x Mode(Height)</para>
/// </summary>
/// <param name="pageWords">The words in the page.</param>
/// <returns></returns>
public IReadOnlyList<TextBlock> GetBlocks(IEnumerable<Word> pageWords)
{
return GetBlocks(pageWords, 0);
}
/// <summary>
/// Get the blocks.
/// <para>Uses 'dominantFontWidthFunc' = Mode(Width), 'dominantFontHeightFunc' = 1.5 x Mode(Height)</para>
/// </summary>
/// <param name="pageWords">The words in the page.</param>
/// <param name="minimumWidth">The minimum width for a block.</param>
public static XYNode GetBlocks(IEnumerable<Word> pageWords, decimal minimumWidth = 0)
public IReadOnlyList<TextBlock> GetBlocks(IEnumerable<Word> pageWords, decimal minimumWidth)
{
return GetBlocks(pageWords, minimumWidth, k => Math.Round(k.Mode(), 3), k => Math.Round(k.Mode() * 1.5m, 3));
}
@@ -30,7 +47,7 @@ namespace UglyToad.PdfPig.DocumentLayoutAnalysis
/// <param name="minimumWidth">The minimum width for a block.</param>
/// <param name="dominantFontWidth">The dominant font width.</param>
/// <param name="dominantFontHeight">The dominant font height.</param>
public static XYNode GetBlocks(IEnumerable<Word> pageWords, decimal minimumWidth,
public IReadOnlyList<TextBlock> GetBlocks(IEnumerable<Word> pageWords, decimal minimumWidth,
decimal dominantFontWidth, decimal dominantFontHeight)
{
return GetBlocks(pageWords, minimumWidth, k => dominantFontWidth, k => dominantFontHeight);
@@ -43,15 +60,24 @@ namespace UglyToad.PdfPig.DocumentLayoutAnalysis
/// <param name="minimumWidth">The minimum width for a block.</param>
/// <param name="dominantFontWidthFunc">The function that determines the dominant font width.</param>
/// <param name="dominantFontHeightFunc">The function that determines the dominant font height.</param>
public static XYNode GetBlocks(IEnumerable<Word> pageWords, decimal minimumWidth,
public IReadOnlyList<TextBlock> GetBlocks(IEnumerable<Word> pageWords, decimal minimumWidth,
Func<IEnumerable<decimal>, decimal> dominantFontWidthFunc,
Func<IEnumerable<decimal>, decimal> dominantFontHeightFunc)
{
var root = new XYLeaf(pageWords); // Create a root node.
return VerticalCut(root, minimumWidth, dominantFontWidthFunc, dominantFontHeightFunc);
XYLeaf root = new XYLeaf(pageWords); // Create a root node.
XYNode node = VerticalCut(root, minimumWidth, dominantFontWidthFunc, dominantFontHeightFunc);
var leafs = node.GetLeafs();
if (leafs.Count > 0)
{
return leafs.Select(l => new TextBlock(l.GetLines())).ToList();
}
return new List<TextBlock>();
}
private static XYNode VerticalCut(XYLeaf leaf, decimal minimumWidth,
private XYNode VerticalCut(XYLeaf leaf, decimal minimumWidth,
Func<IEnumerable<decimal>, decimal> dominantFontWidthFunc,
Func<IEnumerable<decimal>, decimal> dominantFontHeightFunc, int level = 0)
{
@@ -144,7 +170,7 @@ namespace UglyToad.PdfPig.DocumentLayoutAnalysis
return new XYNode(newNodes);
}
private static XYNode HorizontalCut(XYLeaf leaf, decimal minimumWidth,
private XYNode HorizontalCut(XYLeaf leaf, decimal minimumWidth,
Func<IEnumerable<decimal>, decimal> dominantFontWidthFunc,
Func<IEnumerable<decimal>, decimal> dominantFontHeightFunc, int level = 0)
{