Calculate gray value features from a co-occurrence matrix.
The procedure calculates from a co-occurence matrix (CoocMatrix) the energy (Energy), correlation (Correlation), local homogenity (Homogenity) and contrast (Contrast).
The operator cooc_feature2 calculates the gray value features from the part of the input matrix generated by gen_cooc_matrix corresponding to the direction matrix indicated by the parameters LdGrey and Direction according to the following formulae:
Energy: width width ---- ---- \ \ Energy = / / cij * cij ---- ---- i=0 j=0 (Measure for image homogenity) Correlation: width width ---- ---- \ \ / / (i - ux) * (j - uy) * cij ---- ---- i=0 j=0 Correlation = ----------------------------------------- sx * sy (Measure for gray value dependencies) Local homogenity: width width ---- ---- \ \ Homogenity = / / (1 / (1+(i - j) * (i - j)) * cij ---- ---- i=0 j=0 Contrast: width width ---- ---- \ \ Contrast = / / (i - j) * (i - j) * cij ---- ---- i=0 j=0 (Measure for the size of the intensity differences) where width 2^LdGrey - 1 cij Entry of co-occurrence matrix width width ---- ---- \ \ ux / / i * cij ---- ---- i=0 j=0 width width ---- ---- \ \ uy / / j * cij ---- ---- i=0 j=0 width width ---- ---- \ \ sx^2 / / (i - ux)^2 * cij ---- ---- i=0 j=0 width width ---- ---- \ \ sy^2 / / (i - uy)^2 * cij ---- ---- i=0 j=0
The region of the input image is disregarded.
CoocMatrix (input_object) |
image -> object : int4 |
Co-occurrence matrix. |
Energy (output_control) |
real -> real |
Homogeneity of the gray values. |
Correlation (output_control) |
real -> real |
Correlation of gray values. |
Homogenity (output_control) |
real -> real |
Local homogeneity of gray values. |
Contrast (output_control) |
real -> real |
Gray value contrast. |
The operator cooc_feature2 returns the value TRUE if an image with defined gray values is passed and 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.
write_cooc_matrix, intensity__, min_max__, entropy2__, select_grey__