sub_image — Subtract two images.
sub_image(ImageMinuend, ImageSubtrahend : ImageSub : Mult, Add : )
The operator sub_image subtracts two images. The gray values
(g1,g2) of the input images (ImageMinuend and
ImageSubtrahend) are transformed as follows:
g' := (g1 - g2) * Mult + Add
If an overflow or an underflow occurs the values are clipped.
Note that this is not the case with cyclic and direction images.
Several images can be processed in one call. In this case both input parameters contain the same number of images which are then processed in pairs. An output image is generated for every pair.
Please note that the runtime of the operator varies with different
control parameters. For frequently used combinations special
optimizations are used. Additionally, for byte, int2, and uint2
images special optimizations are implemented that use SIMD technology.
The actual application of these special optimizations is controlled by the
system parameter 'mmx_enable' (see set_system).
If 'mmx_enable' is set to 'true' (and the SIMD
instruction set is available), the internal calculations are performed
using SIMD technology.
sub_image can be executed on an OpenCL device for byte, int1, int2,
uint2, int4, real, direction, cyclic, and complex images. However, since
for OpenCL 1.0 only single precision floating point is supported for all
devices, and not all rounding modes are supported, the OpenCL implementation
can produce slightly different results from the scalar or SIMD
implementations.
Note that the acceleration gained by SIMD technology is highest on large,
compact input regions. However, in rare cases, the execution of
sub_image might take significantly longer with SIMD technology
than without, depending on the input region and the capabilities of
the hardware. In these cases, the use of SIMD
technology can be avoided by set_system(::'mmx_enable','false':).
ImageMinuend (input_object) (multichannel-)image(-array) → object (byte* / int1* / int2* / uint2* / int4* / int8 / real* / direction* / cyclic* / complex*) *allowed for compute devices
Minuend(s).
ImageSubtrahend (input_object) (multichannel-)image(-array) → object (byte* / int1* / int2* / uint2* / int4* / int8 / real* / direction* / cyclic* / complex*) *allowed for compute devices
Subtrahend(s).
ImageSub (output_object) (multichannel-)image(-array) → object (byte / int1 / int2 / uint2 / int4 / int8 / real / direction / cyclic / complex)
Result image(s) by the subtraction.
Mult (input_control) number → (real / integer)
Correction factor.
Default value: 1.0
Suggested values: 0.0, 1.0, 2.0, 3.0, 4.0
Typical range of values: -255.0
≤
Mult
≤
255.0
Minimum increment: 0.001
Recommended increment: 0.1
Add (input_control) number → (real / integer)
Correction value.
Default value: 128.0
Suggested values: 0.0, 128.0, 256.0
Typical range of values: -512.0
≤
Add
≤
512.0
Minimum increment: 0.01
Recommended increment: 1.0
read_image(Image1,'fabrik') dev_display (Image1) read_image(Image2,'monkey') dev_display (Image2) sub_image (Image1, Image2, Result, 1, 100) dev_display (Result)
The operator sub_image returns the value 2 (H_MSG_TRUE) if the
parameters are correct. 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.
add_image,
mult_image,
dyn_threshold,
check_difference
Foundation