OCR Results
This section describes the format of the results produced by an OCR analysis task.
Results by Line
The following XML shows records from the Result
track of an OCR task. The analysis engine produces one record for each line of text in the analyzed image or video frame.
If you are processing a document, then unless you have set ProcessTextElements=FALSE
, some of the records in the Result
track could represent text that has been extracted from text elements that were present in the document.
<record> ... <trackname>OCR.Result</trackname> <OCRResult> <id>c0cf6d75-ad43-4fce-8589-e2a297923996</id> <text>New rover discovers life on Mars</text> <region> <left>35</left> <top>21</top> <width>290</width> <height>15</height> </region> <confidence>99</confidence> <angle>0</angle> <block>0</block> <fontSize>13.56</fontSize> <source>image</source> <parentID>4d69390f-a8c4-4c5d-a0b0-705a3f98aa9b</parentID> </OCRResult> </record> <record> ... <trackname>OCR.Result</trackname> <OCRResult> <id>e17ee583-e980-4d07-92c1-579657f46c3e</id> <text>Some more text</text> <region> <left>89</left> <top>66</top> <width>140</width> <height>15</height> </region> <confidence>99</confidence> <angle>0</angle> <block>1</block> <fontSize>13.56</fontSize> <source>image</source> <parentID>4d69390f-a8c4-4c5d-a0b0-705a3f98aa9b</parentID> </OCRResult> </record>
Each record contains the following information:
-
The
id
element provides a unique identifier for the line of text. The OCR analysis engine issues an ID for each detected appearance of a line of text. If you are running OCR on video and consecutive frames show the same text, all records related to that appearance will have the same ID.For example, if text appears in the same location for fifty consecutive video frames, the engine uses the same ID for each record in the data track and produces a single record in the result track. The record in the result track will have a timestamp that covers all fifty frames.
If the text moves to a different location on the screen, or disappears and then reappears, the engine considers this as a new detection and produces a new ID and a new record in the result track.
- The
text
element contains the text recognized by OCR. - The
region
element describes the position of the text in the ingested media. If the record represents a text element that has been extracted from a document, the region is accurate only if the source media was a PDF file or a presentation format (such as Microsoft PowerPoint). Position information is not extracted from other document formats. - The
confidence
element provides the confidence score for the OCR process (from 0 to 100). For text that was extracted from a text element in a document, the confidence score is always100
. - The
angle
element gives the orientation of the text (rotated clockwise in degrees from upright). - The
block
element indicates which block of text the result belongs to. Media Server starts counting at zero and increments the counter each time it recognizes a new heading, paragraph, or table. The counter is reset to zero at the start of each page. For example, a page that consists of ten paragraphs will have blocks numbered from zero to nine, in logical reading order. A table, including headings, columns, and rows, is considered to be a single block. - The
fontSize
element provides information about the font size. Larger values may indicate that the text is a heading or more important than other blocks that have a smaller font size. If you know the resolution at which the image was scanned or created (in dots per inch), you can convert this value to points by multiplying it by 72 / DPI. -
The
source
element specifies the origin of the text. The possible values are:image
- static text from an image or video.image table
- text from an image that forms part of a table. The record will be referenced by anOCRTableResult
record (see Tables).scroller, left
- text from video of a news ticker, with text scrolling from right to left.text
- text from a text element in a document.text table
- text from a text element in a PDF file that forms part of a table. The record will be referenced by anOCRTableResult
record (see Tables).
-
The
parentID
element is empty, unless you configure the analysis engine withRegion=Input
in which case it contains the UUID of the input record. This provides a way to link the result with other records (from another analysis task) that supplied the region to analyze. To generate a single record combining the information, you can use the Combine ESP engine and the example Lua scriptparentuuidMatch.lua
.
Results by Word
OCR also produces a WordResult
output track. This track contains a record for each recognized word. The following XML shows an example record.
NOTE: Text that is extracted from a text element in a document is not output to the WordResult
or WordData
tracks.
<record> ... <trackname>OCR.WordResult</trackname> <OCRResult> <id>c0cf6d75-ad43-4fce-8589-e2a297923996</id> <text>New</text> <region> <left>35</left> <top>21</top> <width>39</width> <height>15</height> </region> <confidence>99</confidence> <angle>0</angle> <block>0</block> <fontSize>13.56</fontSize> <source>image</source> <parentID>4d69390f-a8c4-4c5d-a0b0-705a3f98aa9b</parentID> </OCRResult> </record>
Each record contains the following information:
- The
id
element provides a unique identifier for the word. - The
text
element contains the recognized word. - The
region
element describes the position of the word. - The
confidence
,angle
,block
,fontSize
, andsource
elements provide the same information as described for the result track. - The
parentID
element provides the identifier of the line of text to which the word belongs. This identifier will match a record in theResult
track, and you can use that record to obtain information about the line.
Results by Character
When you analyze an image or document (but not video), OCR produces a CharResult
output track. This track contains a record for each line of text. However, the records in this track also provide detail about individual characters. The following XML shows an example record.
NOTE: Text that is extracted from a text element in a document is not output to the CharResult
track.
<record> ... <trackname>OCR.CharResult</trackname> <OCRDetail> <id>c0cf6d75-ad43-4fce-8589-e2a297923996</id> <text>New rover discovers life on Mars</text> <region> <left>35</left> <top>21</top> <width>290</width> <height>15</height> </region> <angle>0</angle> <block>0</block> <fontSize>13.56</fontSize> <parentID>4d69390f-a8c4-4c5d-a0b0-705a3f98aa9b</parentID> <character> <text>N</text> <region> <left>35</left> <top>21</top> <width>12</width> <height>15</height> </region> </character> <character> <text>e</text> <region> <left>49</left> <top>25</top> <width>10</width> <height>11</height> </region> </character> ... </OCRDetail> </record>
Each record includes the following information:
- The
id
element provides a unique identifier for the line of text. Every record in theCharResult
track has a differentid
. - The
text
,region
,angle
,block
,fontSize
, andparentID
elements provide the same information as described for the result track. -
There is a
character
element for each character on the line, including spaces. This element includes the following information:text
- the character that was recognized. This element is empty if the character is a space.region
- the location of the character in the source media.
Page Information
When you analyze an image or document (but not video), OCR produces a PageResult
track that provides information about each page.
<record> <pageNumber>1</pageNumber> <trackname>OCR.PageResult</trackname> <OCRPageResult> <id>69ad32b4-3f7b-4b92-b153-7bbe6f850e20</id> <alphabet>Latin</alphabet> <mode>Document</mode> <orientation>0</orientation> <parentID/> </OCRPageResult> </record>
- The
alphabet
element provides a space-separated list of alphabets that were used on the page. The value can also be "Unknown" if Media Server failed to recognize the text. - The
mode
element describes the mode used by the OCR engine. For descriptions of these modes, see the documentation for theOcrMode
configuration parameter. This element will never contain the value "Auto", instead Media Server reports the mode that was chosen. - The
orientation
element describes the orientation of the page (in 90-degree increments from upright).
Tables
Media Server can identify tables that occur in images and tables that are constructed from text elements in PDF files. OCR only identifies tables when your session configuration uses the TableResult
track.
When OCR recognizes text that appears to be arranged in a table, Media Server outputs a record in the TableResult
track that describes the table. The record includes enough structure information to reconstruct the table. The records in the TableResult
track do not include the recognized text, instead they include record IDs that match the records in the Result
, WordResult
, and CharResult
tracks. This means that when a table is identified, some of the records in the Result
, WordResult
, and CharResult
tracks will represent table cells rather than lines of text. For example:
<record> ... <trackname>OCR.TableResult</trackname> <OCRTableResult> <id>6596a664-b69a-4a33-b9fc-8adb2be6c37f</id> <region> <left>256</left> <top>166</top> <width>1213</width> <height>362</height> </region> <block>0</block> <columnCount>9</columnCount> <rowCount>10</rowCount> <row> <cell> <columnSpan>1</columnSpan> </cell> <cell> <columnSpan>2</columnSpan> <OCRResultID>2240914c-440c-40cc-9254-c3c59727953e</OCRResultID> </cell> <cell> <columnSpan>3</columnSpan> </cell> <cell> <columnSpan>3</columnSpan> <OCRResultID>9ea804cc-a1a2-4d31-99f8-d1d96a3a1c9e</OCRResultID> </cell> </row> ... <parentID>4d69390f-a8c4-4c5d-a0b0-705a3f98aa9b</parentID> </OCRTableResult> </record>
Each record contains the following elements:
id
- a unique identifier for the table.region
- the position and size of the table in the media source.block
- indicates which block of text the result belongs to. Media Server starts counting at zero and increments the counter each time it recognizes a new heading, paragraph, or table. The counter is reset to zero at the start of each page. For example, a page that consists of ten paragraphs will have blocks numbered from zero to nine, in logical reading order. A table, including headings, columns, and rows, is considered to be a single block.columnCount
- the total number of columns.rowCount
- the total number of rows.row
- contains the information for a single row. Eachrow
element containscell
elements. Usually the number of cells in a row matches the value ofcolumnCount
, but there can be fewer when cells span multiple columns. The number of columns spanned by a cell is given by thecolumnSpan
element. TheOCRResultID
element provides the ID of an OCR result. This ID matches the ID of relevant records in theResult
,WordResult
, andCharResult
tracks, so that you can obtain the recognized text. If the cell is empty, theOCRResultID
element is omitted.- The
parentID
element is empty, unless you configure the analysis engine withRegion=Input
in which case it contains the UUID of the input record. This provides a way to link the result with other records (from another analysis task) that supplied the region to analyze. To generate a single record combining the information, you can use the Combine ESP engine and the example Lua scriptparentuuidMatch.lua
.
Media Server includes an example session configuration and XSL transform, named Table.cfg
and toHTMLTable.xsl
, that use the information in the TableResult
track to output HTML tables.