Halcon image enhancement operator summary

1. Grayscale linear transformation
1.1, scale_image
g' := g * Mult + Add
g is the current grayscale value, Mult is the multiplied coefficient, and Add is the added offset value. It
can be seen from the formula that scale_image is used for processing The image is a change of (multiple + offset)
1.2, scale_image_max
calculates the maximum and minimum values ​​of pixels, scales each pixel according to the maximum value, and stretches the gray value to 0-255
1.3, invert_image
g' = 255-g
inversion Image pixel value
2. Grayscale nonlinear transformation
2.1, log_image
performs logarithmic transformation on the picture
g' = ln(g+1)
is used to improve the pixel value of the dark part
2.2, exp_image
performs exponential transformation on the picture
g'=g e power
It is used to improve the pixel value of the bright part
. 3. Image enhancement contrast and illumination
3.1. Emphasize
enhances image contrast
and enhances the high-frequency areas (edges and corners) of the image to make the image look clearer.
3.2. Illuminate
enhances the image illumination
and enhances the high-frequency areas (edges and corners) of the image to make the image look clearer.
Four. Histogram equalization
4.1, equ_histo_image
enhances the contrast of the image through the linearization of the gray histogram
V. Morphology of grayscale images
5.1, gray_erosion_rect
grayscale corrosion, reduce brightness, eliminate white spots.
5.2, gray_dilation_rect
gray expansion, increase brightness, eliminate black spots.
5.3, gray_opening
grayscale opening operation, the grayscale first corrodes and then expands, used to remove isolated white points.
5.4, ​​gray_closing
grayscale closing operation, the grayscale first expands and then corrodes, used to remove isolated black spots.
5.5, gray_range_rect
uses a rectangular structure element to slide in the image, new value = (largest in the rectangle) gray value - (largest in the rectangle) minimum gray value 6. Operation between
pictures
6.1, add_image
g' := ( g1 + g2) * Mult + Add Adds
the gray value of the two images to
6.2, sub_image
g' := (g1 - g2) * Mult + Add
subtracts the gray value of the two images to
6.3, mult_image
g' := (g1 * g2) * Mult + Add Multiply
the gray value of the two images
6.4, div_image
g' := g1 / g2 * Mult + Add
Divide the gray value of the two images
7. Image smoothing
7.1, coherence_enhancing_diff
performs image coherence enhancement diffusion
Anisotropic diffusion processing is performed on the input image Image to increase the correlation of the image structure contained in the Image.
In particular, discontinuous image edges are connected by diffusion without smoothing perpendicular to their dominant directions.
Can make the boundary of the image blurred
7.2, mean_curvature_flow
Use grayscale histogram curvature smoothing on the image to make the image smooth.
Can reduce image interference
7.3. Filtering operations: Gaussian filtering, mean filtering, median filtering, bilateral filtering, guided filtering.