* This program shows how to detect defects (scratches) in
* an inhomogeneously illuminated surface by filtering in
* the frequency domain.
* First, a suitable bandpass filter is created. Then, the
* input image is fourier transformed and filtered in the
* frequency domain, so that high frequency information is
* enhanced. Finally, it is transformed back to the
* spatial domain and the enhanced defects are post-processed
* by morphology.
* 频域+空域
dev_update_off ()
dev_close_window ()
read_image (Image, 'surface_scratch')
invert_image (Image, ImageInverted)
get_image_size (Image, Width, Height)
dev_open_window (0, 0, Width, Height, 'black', WindowHandle)
set_display_font (WindowHandle, 16, 'mono', 'true', 'false')
dev_display (Image)
*
* Optimize the speed of the fast fourier transform
* Message := 'Optimize the speed of the fast fourier transform.'
* Message[1] := 'Please wait...'
* disp_message (WindowHandle, Message, 'window', 12, 12, 'black', 'true')
* optimize_rft_speed (Width, Height, 'standard')
* disp_continue_message (WindowHandle, 'black', 'true')
* stop ()
*
* Enhance the scratches by filtering in the frequency domain正弦带通滤波器
gen_sin_bandpass (ImageBandpass, 0.4, 'none', 'rft', Width, Height)
rft_generic (ImageInverted, ImageFFT, 'to_freq', 'none', 'complex', Width)
convol_fft (ImageFFT, ImageBandpass, ImageConvol)
rft_generic (ImageConvol, Lines, 'from_freq', 'n', 'byte', Width)
*
* Segment the scratches by using morphology
threshold (Lines, Region, 5, 255)
connection (Region, ConnectedRegions)
select_shape (ConnectedRegions, SelectedRegions, 'area', 'and', 5, 5000)
dilation_circle (SelectedRegions, RegionDilation, 5.5)
union1 (RegionDilation, RegionUnion)
reduce_domain (Image, RegionUnion, ImageReduced)
lines_gauss (ImageReduced, LinesXLD, 0.8, 3, 5, 'dark', 'false', 'bar-shaped', 'false')
union_collinear_contours_xld (LinesXLD, UnionContours, 40, 3, 3, 0.2, 'attr_keep')
select_shape_xld (UnionContours, SelectedXLD, 'contlength', 'and', 15, 1000)
gen_region_contour_xld (SelectedXLD, RegionXLD, 'filled')
union1 (RegionXLD, RegionUnion)
dilation_circle (RegionUnion, RegionScratches, 10.5)
*
* Display the results
dev_set_draw ('margin')
dev_set_line_width (3)
dev_set_colored (12)
dev_display (Image)
dev_display (RegionScratches)
