HALCON 21.11.0.0 / HALCON Operator Reference / OCR / Segmentation
ClassesClasses | | Operators

text_line_slanttext_line_slantTextLineSlantTextLineSlanttext_line_slant (Operator)

Name

text_line_slanttext_line_slantTextLineSlantTextLineSlanttext_line_slant — Determines the slant of characters of a text line or paragraph.

Signature

text_line_slant(Region, Image : : CharHeight, SlantFrom, SlantTo : SlantAngle)

Herror text_line_slant(const Hobject Region, const Hobject Image, const Hlong CharHeight, double SlantFrom, double SlantTo, double* SlantAngle)

Herror T_text_line_slant(const Hobject Region, const Hobject Image, const Htuple CharHeight, const Htuple SlantFrom, const Htuple SlantTo, Htuple* SlantAngle)

void TextLineSlant(const HObject& Region, const HObject& Image, const HTuple& CharHeight, const HTuple& SlantFrom, const HTuple& SlantTo, HTuple* SlantAngle)

HTuple HRegion::TextLineSlant(const HImage& Image, Hlong CharHeight, double SlantFrom, double SlantTo) const

static void HOperatorSet.TextLineSlant(HObject region, HObject image, HTuple charHeight, HTuple slantFrom, HTuple slantTo, out HTuple slantAngle)

HTuple HRegion.TextLineSlant(HImage image, int charHeight, double slantFrom, double slantTo)

def text_line_slant(region: HObject, image: HObject, char_height: int, slant_from: float, slant_to: float) -> Sequence[float]

def text_line_slant_s(region: HObject, image: HObject, char_height: int, slant_from: float, slant_to: float) -> float

Description

text_line_slanttext_line_slantTextLineSlantTextLineSlantTextLineSlanttext_line_slant determines the slant of a single text line or a paragraph.

The parameter RegionRegionRegionRegionregionregion specifies the area of the image in which the text lines are located. The RegionRegionRegionRegionregionregion is only used to reduce the working area. To determine the slant, the gray values inside that area are used. The text lines are segmented by the operator text_line_slanttext_line_slantTextLineSlantTextLineSlantTextLineSlanttext_line_slant itself. If more than one region is passed, the numerical values of the orientation angle are stored in a tuple, the position of a value in the tuple corresponding to the position of the region in the input tuple.

CharHeightCharHeightCharHeightCharHeightcharHeightchar_height specifies the approximately high of the existing text lines in the region RegionRegionRegionRegionregionregion. It's assumed, that the text lines are darker than the background.

The search area can be restricted by the parameters SlantFromSlantFromSlantFromSlantFromslantFromslant_from and SlantToSlantToSlantToSlantToslantToslant_to, whereby also the runtime of the operator is influenced.

With the calculated slant angle SlantAngleSlantAngleSlantAngleSlantAngleslantAngleslant_angle and operators for affine transformations, the slant can be removed from the characters. This may simplify the character separation for OCR applications. To work correctly all characters of a region should have nearly the same slant.

Execution Information

Parameters

RegionRegionRegionRegionregionregion (input_object)  region(-array) → objectHRegionHObjectHRegionHobject

Area of text lines.

ImageImageImageImageimageimage (input_object)  singlechannelimage → objectHImageHObjectHImageHobject (byte / uint2)

Input image.

CharHeightCharHeightCharHeightCharHeightcharHeightchar_height (input_control)  integer → HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Height of the text lines.

Default value: 25

Typical range of values: 1 ≤ CharHeight CharHeight CharHeight CharHeight charHeight char_height

Restriction: CharHeight >= 1

SlantFromSlantFromSlantFromSlantFromslantFromslant_from (input_control)  angle.rad → HTuplefloatHTupleHtuple (real) (double) (double) (double)

Minimum slant of the characters

Default value: -0.523599

Typical range of values: -0.785398 ≤ SlantFrom SlantFrom SlantFrom SlantFrom slantFrom slant_from ≤ 0.785398

Restriction: - pi / 4 <= SlantFrom && SlantFrom <= SlantTo

SlantToSlantToSlantToSlantToslantToslant_to (input_control)  angle.rad → HTuplefloatHTupleHtuple (real) (double) (double) (double)

Maximum slant of the characters

Default value: 0.523599

Typical range of values: -0.785398 ≤ SlantTo SlantTo SlantTo SlantTo slantTo slant_to ≤ 0.785398

Restriction: - pi / 4 <= SlantTo && SlantTo <= pi / 4

SlantAngleSlantAngleSlantAngleSlantAngleslantAngleslant_angle (output_control)  angle.rad(-array) → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)

Calculated slant of the characters in the region

Example (HDevelop)

hom_mat2d_identity(HomMat2DIdentity)
read_image(Image,'dot_print_slanted')
* correct slant
text_line_slant(Image,Image,50,rad(-45),rad(45),SlantAngle)
hom_mat2d_slant(HomMat2DIdentity,-SlantAngle,'x',0,0,HomMat2DSlant)
affine_trans_image(Image,Image,HomMat2DSlant,'constant','true')

Result

If the input parameters are set correctly, the operator text_line_slanttext_line_slantTextLineSlantTextLineSlantTextLineSlanttext_line_slant returns the value TRUE. Otherwise an exception will be raised.

Possible Successors

hom_mat2d_slanthom_mat2d_slantHomMat2dSlantHomMat2dSlantHomMat2dSlanthom_mat2d_slant, affine_trans_imageaffine_trans_imageAffineTransImageAffineTransImageAffineTransImageaffine_trans_image, affine_trans_image_sizeaffine_trans_image_sizeAffineTransImageSizeAffineTransImageSizeAffineTransImageSizeaffine_trans_image_size

Module

Foundation

ClassesClasses | | Operators
HALCON Operator Reference 21.11.0.0 Copyright © 1996-2021 MVTec Software GmbH
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