illuminate🔗
Short description🔗
illuminate — Illuminate image.
Signature🔗
illuminate( image Image, out image ImageIlluminate, extent.x MaskWidth, extent.y MaskHeight, real Factor )
Description🔗
The operator illuminate enhances contrast. Very dark parts of
the image are “illuminated” more strongly, very light ones are
“darkened”. If \(orig\) is the original gray value and \(mean\) is
the corresponding gray value of the low pass filtered image detected
via the operators mean_image and filter size
MaskHeight x MaskWidth. For byte-images val equals 127,
for int2-images and uint2-images val equals the median value.
The resulting gray value is \(new\):
new = round ( (val - mean) * Factor + orig ).
The low pass should have rather large dimensions (30 x 30 to
200 x 200). Reasonable parameter combinations might be:
Height Width Factor
---------------------
40 40 0.55
100 100 0.7
150 150 0.8
i.e. the larger the low pass mask is chosen, the larger
Factor should be as well.
The following “spotlight effect” should be noted: If, for example,
a dark object is in front of a light wall the object as well as the wall,
which is already light in the immediate proximity of the object contours,
are lightened by the operator illuminate. This corresponds
roughly to the effect that is produced when the object is illuminated by a
strong spotlight. The same applies to light objects in front of a darker
background. In this case, however, the fictitious “spotlight” darkens
objects.
Attention🔗
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.
Execution information🔗
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.
-
Automatically parallelized on channel level.
-
Automatically parallelized on internal data level.
Parameters🔗
Image (input_object) (multichannel-)image(-array) → object (byte / int2 / uint2)
Image to be enhanced.
ImageIlluminate (output_object) (multichannel-)image(-array) → object (byte / int2 / uint2)
“Illuminated” image.
MaskWidth (input_control) extent.x → (integer)
Width of low pass mask.
Default: 101
Suggested values: 31, 41, 51, 71, 101, 121, 151, 201
Minimum increment: 2
Recommended increment: 10
Restriction: MaskWidth < width(Image) * 2
MaskHeight (input_control) extent.y → (integer)
Height of low pass mask.
Default: 101
Suggested values: 31, 41, 51, 71, 101, 121, 151, 201
Minimum increment: 2
Recommended increment: 10
Restriction: MaskHeight < height(Image) * 2
Factor (input_control) real → (real)
Scales the “correction gray value” added to the original gray values.
Default: 0.7
Suggested values: 0.3, 0.5, 0.7, 1.0, 1.5, 2.0, 3.0, 5.0
Value range: 0.0 ≤ Factor
Minimum increment: 0.01
Recommended increment: 0.2
Example🔗
(HDevelop)
read_image(Image,'fabrik')
dev_display (Image)
illuminate(Image,Better,40,40,0.55)
dev_display (Better)
read_image(&Image,"fabrik")\;
disp_image(Image,WindowHandle)\;
illuminate(Image,&Better,40,40,0.55)\;
disp_image(Better,WindowHandle)\;
Result🔗
If the parameter values are correct the operator illuminate
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.
Combinations with other operators🔗
Combinations
Possible successors
Alternatives
scale_image_max, equ_histo_image, equ_histo_image_rect, mean_image, sub_image
See also
Module🔗
Foundation