TIEVisionImage.findSkewAngle

Declaration

function findSkewAngle(maxAngle: Double = 7.0; confidence: double_p = nil): Double; safecall;

Description

Measures the skew of the text lines in a document image (via Leptonica) without changing the image.
Returns the angle, in degrees, that the image needs to be rotated clockwise to make the text lines horizontal (negative values mean counter-clockwise). Returns 0 if no skew could be measured.
The image should contain dark text on a light background. It is binarized with Otsu for the measurement.

Parameter	Description
maxAngle	Largest skew to search for, in degrees (greater than 0 and at most 45)
confidence	Optional. Receives the confidence of the measurement. A value of 3 or more is reliable. 0 means no skew could be measured

Note: This only measures small skews. Use getOrientation to detect pages rotated by 90, 180 or 270 degrees.

Examples

Also see: Automated Samples

var
  angle, conf: Double;
begin
  angle := ImageEnView1.IEBitmap.GetIEVisionImage().findSkewAngle( 7.0, @conf );
  if conf >= 3 then
    ShowMessage( Format( 'Skew: %.2f deg', [ angle ] ));
end;

// Measure the skew of the text lines of a document
angle := ImageEnView1.IEBitmap.GetIEVisionImage().findSkewAngle( 7, @conf );
s := Format( 'Skew: %.2f deg (Confidence: %.1f)', [ angle, conf ]);
For the following image, the result is "Rotate -1.31 deg clockwise to correct (Confidence: 5.1)"

TIEVisionImage.findSkewAngle