emphasize
— Enhance contrast of the image.
emphasize(Image : ImageEmphasize : MaskWidth, MaskHeight, Factor : )
The operator emphasize
emphasizes high frequency areas of the
image (edges and corners). The resulting images appears sharper.
First the procedure carries out a filtering with the low pass
(mean_image
). The resulting gray values (res) are calculated
from the obtained gray values (mean) and the original gray values
(orig) as follows:
res := round((orig - mean) * Factor) + orig
Factor
serves as measurement of the increase in contrast.
The division frequency is determined via the size of the filter matrix:
The larger the matrix, the lower the division frequency.
As an edge treatment the gray values are mirrored at the edges of the image. Overflow and/or underflow of gray values is clipped.
Note that filter operators may return unexpected results if an image with a reduced domain is used as input. Please refer to the chapter Filters.
Image
(input_object) (multichannel-)image(-array) →
object (byte / int2 / uint2)
Image to be enhanced.
ImageEmphasize
(output_object) (multichannel-)image(-array) →
object (byte / int2 / uint2)
contrast enhanced image.
MaskWidth
(input_control) extent.x →
(integer)
Width of low pass mask.
Default value: 7
Suggested values: 3, 5, 7, 9, 11, 15, 21, 25, 31, 39
Typical range of values: 3
≤
MaskWidth
≤
201
Minimum increment: 2
Recommended increment: 2
MaskHeight
(input_control) extent.y →
(integer)
Height of the low pass mask.
Default value: 7
Suggested values: 3, 5, 7, 9, 11, 15, 21, 25, 31, 39
Typical range of values: 3
≤
MaskHeight
≤
201
Minimum increment: 2
Recommended increment: 2
Factor
(input_control) real →
(real)
Intensity of contrast emphasis.
Default value: 1.0
Suggested values: 0.3, 0.5, 0.7, 1.0, 1.4, 1.8, 2.0
Typical range of values: 0.0
≤
Factor
≤
20.0
(sqrt)
Minimum increment: 0.01
Recommended increment: 0.2
Restriction: 0 < Factor && Factor < 20
read_image(Image,'mreut') dev_display (Image) draw_region(Region,WindowHandle) reduce_domain(Image,Region,Mask) emphasize(Mask,Sharp,7,7,2.0) dev_display (Sharp)
If the parameter values are correct the operator emphasize
returns the value 2 (H_MSG_TRUE)
The behavior in case of empty input (no input images available) is
set via the operator
set_system(::'no_object_result',<Result>:)
.
If necessary an exception is raised.
mean_image
,
sub_image
,
laplace
,
add_image
Foundation