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)

Description

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

The parameter RegionRegionRegionregionregion specifies the area of the image in which the text lines are located. The RegionRegionRegionregionregion 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_slantTextLineSlantTextLineSlanttext_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.

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

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

With the calculated slant angle SlantAngleSlantAngleSlantAngleslantAngleslant_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

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Automatically parallelized on tuple level.

Parameters

RegionRegionRegionregionregion (input_object) region(-array) → object

Area of text lines.

ImageImageImageimageimage (input_object) singlechannelimage → object (byte / uint2)

Input image.

CharHeightCharHeightCharHeightcharHeightchar_height (input_control) integer → (integer)

Height of the text lines.

Default: 25

Value range: 1 ≤ CharHeight CharHeight CharHeight charHeight char_height

SlantFromSlantFromSlantFromslantFromslant_from (input_control) angle.rad → (real)

Minimum slant of the characters

Default: -0.523599

Value range: -0.785398 ≤ SlantFrom SlantFrom SlantFrom slantFrom slant_from ≤ 0.785398

Restriction: SlantFrom <= SlantTo

SlantToSlantToSlantToslantToslant_to (input_control) angle.rad → (real)

Maximum slant of the characters

Default: 0.523599

Value range: -0.785398 ≤ SlantTo SlantTo SlantTo slantTo slant_to ≤ 0.785398

Restriction: SlantFrom <= SlantTo

SlantAngleSlantAngleSlantAngleslantAngleslant_angle (output_control) angle.rad(-array) → (real)

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_slantTextLineSlantTextLineSlanttext_line_slant returns the value 2 ( H_MSG_TRUE) . Otherwise an exception will be raised.

Possible Successors

hom_mat2d_slanthom_mat2d_slantHomMat2dSlantHomMat2dSlanthom_mat2d_slant, affine_trans_imageaffine_trans_imageAffineTransImageAffineTransImageaffine_trans_image, affine_trans_image_sizeaffine_trans_image_sizeAffineTransImageSizeAffineTransImageSizeaffine_trans_image_size

Module

Foundation

Operators