Digital Signal Processing Reference
In-Depth Information
Second is decomposition of high-frequency coefficients after threshold. Choose an
appropriate threshold for each level of decomposition, and to quantify the layer of
high-frequency coefficients of the soft threshold.
The last is reconstruction of image signal wavelet. Low frequency coefficients after
threshold deal with layers of detail (high-frequency coefficient) of two-dimensional
signal, wavelet reconstruction based on wavelet decomposition of the N layer approx-
imation.
Fig. 3.
The image after wavelet de-noising
2.4
Image Black and White
Corrosion is a process to eliminate the boundary points, the result is target decreased
narrows and the hole increases, which can effectively eliminate isolated noise points.
Expansion sucked in contact with the object of all backgrounds merged into objects in
the process. The process of corrosion and expansion as the open operation, it has to
eliminate small objects and thin at the separation of the role of objects and smooth
larger objects boundaries.
Image minus operation is pre-operating as a complex image processing. It is using
special function to do minus between images or constants. The functions will be two
of the input image to do the corresponding pixel value minus, and then returns the
result to the corresponding pixel of the output image. It treats the background to the
current image of the morphological opening operation results, the background is then
subtracted from the current image.
Fig. 4.
The image after black and white preprocess
