image preprocessing

  • Last Post 11 October 2018
Rama Reddy posted this 08 October 2018

Hi Team,

How to fine required rotation angle for given image to extract the text from it? what is the difference between rotation,skew and orientation angles?

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Helen Osetrova posted this 09 October 2018

Hi Rama,


The DetectOrientation method of the FRPage object detects text orientation on the image. The method returns the TextOrientation object, if orientation has been detected successfully, and NULL, if the program failed to detect orientation. Please find more in Developer'sHelp → API Reference → Document-Related Objects → FRPage → DetectOrientation Method of the FRPage Object. The OrientationDetectionParams object provides access to the parameters of orientation detection. Please learn more from the Developer's Help → API Reference → Parameter Objects → Preprocessing, Analysis, Recognition, and Synthesis Parameters → OrientationDetectionParams Object section. You can also use the CorrectOrientation property of the PagePreprocessingParams object to correct page orientation automatically.


Skew can be corrected only for angles not greater than 20 degrees. By default, skew is corrected by horizontal and vertical text lines. Other types of skew correction should be used only in the cases they are intended for. See Developer's Help → API Reference → Enumerations → CorrectSkewModeEnum for details.


Rotation property of the PrepareImageMode object specifies the rotation angle to apply to the image during preparation. The default option specifies no rotation, other possible options specify clockwise, counterclockwise, and upside-down rotation. Kindly see Developer's Help → API Reference → Enumerations → RotationTypeEnum for details.


Rama Reddy posted this 11 October 2018

Hi Helen,


Thank you. Is rotation is applicable when we need to rotate image ? and when and where  orientation is applicable?