text_line_slant🔗
Short description🔗
text_line_slant — Determines the slant of characters of a text line or paragraph.
Signature🔗
text_line_slant( region Region, image Image, integer CharHeight, angle.rad SlantFrom, angle.rad SlantTo, out angle.rad SlantAngle )
Description🔗
text_line_slant determines the slant of a single text line or a
paragraph.
The parameter Region specifies the area of the image in which the
text lines are located. The Region 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_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.
CharHeight specifies the approximately high of the existing text
lines in the region Region. It’s assumed, that the text lines are
darker than the background.
The search area can be restricted by the parameters SlantFrom and
SlantTo, whereby also the runtime of the operator is influenced.
With the calculated slant angle SlantAngle 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🔗
Execution information
-
Multithreading type: reentrant (runs in parallel with non-exclusive operators).
-
Multithreading scope: global (may be called from any thread).
Parameters🔗
Region (input_object) region(-array) → object
Area of text lines.
Image (input_object) singlechannelimage → object (byte / uint2)
Input image.
CharHeight (input_control) integer → (integer)
Height of the text lines.
Default: 25
Value range: 1 ≤ CharHeight
SlantFrom (input_control) angle.rad → (real)
Minimum slant of the characters
Default: -0.523599
Value range: -0.785398 ≤ SlantFrom ≤ 0.785398
Restriction: SlantFrom <= SlantTo
SlantTo (input_control) angle.rad → (real)
Maximum slant of the characters
Default: 0.523599
Value range: -0.785398 ≤ SlantTo ≤ 0.785398
Restriction: SlantFrom <= SlantTo
SlantAngle (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_slant returns the value 2 (H_MSG_TRUE).
Otherwise an exception will be raised.
Combinations with other operators🔗
Module🔗
Foundation