What does word level confidence of zero mean?
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farhad khalafi
Aug 18, 2019, 9:10:41 AM8/18/19
to tesseract-ocr
Hi,
On occasions when I get the confidence level for a specific word from page level iterator, I receive a value of 0.
When I examine the word further, it appears that all characters have high confidence and often the word is marked as in the dictionary.
What I would like to know is how a word-level confidence should be interpreted in such cases.
If I crop the same image to the bottom 2 lines and run recognition on the smaller image, the confidence for the same word goes up to 96%.
Thanks.
Here is an example for word "England:" towards the bottom of the linked TIFF image:
| Name | Value | Type | |
|---|---|---|---|
| ◢ | [176] | {FlowingText [0%] [0] England:} | Tesseract.TessWord |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 811 Y = 2238 Width = 91 Height = 18} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 0 | float | |
| DeskewAngle | 0.0002258866 | float | |
| ▶ Font | {Tesseract.TessFontAttributes} | Tesseract.TessFontAttributes | |
| InDictionary | true | bool | |
| IsNumeric | false | bool | |
| Language | "eng" | string | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | "England:" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection |
And for the individual symbols in the same word:
| Name | Value | Type | |
|---|---|---|---|
| ◢ | [912] | {FlowingText [100%] [0] E} | Tesseract.TessSymbol |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 811 Y = 2238 Width = 17 Height = 18} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 99.55842 | float | |
| DeskewAngle | 0.0002258866 | float | |
| IsDropcap | false | bool | |
| IsSubscript | false | bool | |
| IsSuperscript | false | bool | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | "E" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection | |
| ◢ | [913] | {FlowingText [100%] [0] n} | Tesseract.TessSymbol |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 811 Y = 2238 Width = 27 Height = 14} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 99.55082 | float | |
| DeskewAngle | 0.0002258866 | float | |
| IsDropcap | false | bool | |
| IsSubscript | false | bool | |
| IsSuperscript | false | bool | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | "n" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection | |
| ◢ | [914] | {FlowingText [100%] [0] g} | Tesseract.TessSymbol |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 839 Y = 2242 Width = 11 Height = 14} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 99.56353 | float | |
| DeskewAngle | 0.0002258866 | float | |
| IsDropcap | false | bool | |
| IsSubscript | false | bool | |
| IsSuperscript | false | bool | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | "g" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection | |
| ◢ | [915] | {FlowingText [84%] [0] l} | Tesseract.TessSymbol |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 850 Y = 2239 Width = 7 Height = 13} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 84.39856 | float | |
| DeskewAngle | 0.0002258866 | float | |
| IsDropcap | false | bool | |
| IsSubscript | false | bool | |
| IsSuperscript | false | bool | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | "l" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection | |
| ◢ | [916] | {FlowingText [92%] [0] a} | Tesseract.TessSymbol |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 852 Y = 2238 Width = 19 Height = 18} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 91.98873 | float | |
| DeskewAngle | 0.0002258866 | float | |
| IsDropcap | false | bool | |
| IsSubscript | false | bool | |
| IsSuperscript | false | bool | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | "a" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection | |
| ◢ | [917] | {FlowingText [100%] [0] n} | Tesseract.TessSymbol |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 858 Y = 2242 Width = 23 Height = 10} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 99.55326 | float | |
| DeskewAngle | 0.0002258866 | float | |
| IsDropcap | false | bool | |
| IsSubscript | false | bool | |
| IsSuperscript | false | bool | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | "n" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection | |
| ◢ | [918] | {FlowingText [100%] [0] d} | Tesseract.TessSymbol |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 870 Y = 2238 Width = 23 Height = 18} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 99.57375 | float | |
| DeskewAngle | 0.0002258866 | float | |
| IsDropcap | false | bool | |
| IsSubscript | false | bool | |
| IsSuperscript | false | bool | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | "d" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection | |
| ◢ | [919] | {FlowingText [100%] [0] :} | Tesseract.TessSymbol |
| ▶ BaseLine | {X = 811 Y = 2253 Width = 91 Height = 0} | System.Drawing.Rectangle | |
| BlockType | FlowingText | Tesseract.PolyBlockType | |
| ▶ Bounds | {X = 882 Y = 2239 Width = 20 Height = 13} | System.Drawing.Rectangle | |
| ▶ Choices | Count = 0 | System.Collections.Generic.List<Tesseract.TessChoice> | |
| Confidence | 99.5546341 | float | |
| DeskewAngle | 0.0002258866 | float | |
| IsDropcap | false | bool | |
| IsSubscript | false | bool | |
| IsSuperscript | false | bool | |
| Orientation | PageUp | Tesseract.Orientation | |
| Text | ":" | string | |
| TextLineOrder | TopToBottom | Tesseract.TextLineOrder | |
| WritingDirection | LeftToRight | Tesseract.WritingDirection |
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