Table 4.
Examples of second-order statistics features evaluated on each matrix with their description [23]
| Group of features | Type of feature | Measure |
|---|---|---|
| Gray Level Co-occurrence Matrix (GLCM) | Correlation | Linear dependency of gray level values to their respective voxels in the GLCM |
| Difference Entropy | a measure of the randomness/variability in neighborhood intensity value differences | |
| Difference Average | A measure of the relationship between occurrences of pairs with similar intensity values and occurrences of pairs with differing intensity values | |
| Difference Variance | A measure of heterogeneity that places higher weights on differing intensity level pairs that deviate more from the mean | |
| Joint Energy | A measure of homogeneous patterns in the image | |
| Joint Entropy | A measure of the randomness/variability in neighborhood intensity values | |
| Inverse Difference Moment (IDM), Inverse Difference Moment Normalized (IDMN) and Inverse Difference (ID) | A measure of the local homogeneity of an image | |
| Autocorrelation | A measure of the magnitude of the fineness and coarseness of texture | |
| Joint Average | The mean gray level intensity of the i distribution | |
| Cluster Prominence | A measure of the skewness and asymmetry of the GLCM | |
| Cluster Shade | A measure of the skewness and uniformity of the GLCM | |
| Cluster Tendency | A measure of groupings of voxels with similar gray level values | |
| Contrast | A measure of the local intensity variation, favoring values away from the diagonal | |
| Informational Measure of Correlation (IMC) 1 and 2 and Maximal Correlation Coefficient (MCC) | A quantification of the complexity of the texture | |
| Maximum Probability | Occurrences of the most predominant pair of neighboring intensity values | |
| Sum Average | A measure of the relationship between occurrences of pairs with lower intensity values and occurrences of pairs with higher intensity values | |
| Sum Entropy | A sum of neighborhood intensity value differences | |
| Sum of Squares | A measure in the distribution of neighboring intensity level pairs about the mean intensity level in the GLCM | |
| Gray Level Run Length Matrix (GLRLM) | Short Run Emphasis (SRE) | A measure of the distribution of short run lengths, with a greater value indicative of shorter run lengths and more fine textural textures |
| Long Run Emphasis (LRE) | A measure of the distribution of long run lengths, with a greater value indicative of longer run lengths and more coarse structural textures | |
| Gray Level Non-Uniformity (GLN) and Gray Level Non-Uniformity Normalized (GLNN) | A measure of the similarity of gray level intensity values in the image | |
| Run Length Non-Uniformity (RLN) and Run Length Non-Uniformity Normalized (RLNN) | A measure of the similarity of run lengths throughout the image | |
| Run Percentage (RP) | A measure of the coarseness of the texture by taking the ratio of number of runs and number of voxels in the ROI | |
| Gray Level Variance (GLV) | The variance in gray level intensity for the runs | |
| Run Variance (RV) | The variance in runs for the run lengths | |
| Run Entropy (RE) | a measure of the uncertainty/randomness in the distribution of run lengths and gray levels | |
| Low and High Gray Level Run Emphasis (LGLRE and HGLRE) | A measure of the distribution of low and higher gray level values | |
| Short and Long Run Low Gray Level Emphasis (SRLGLE and LRLGLE) | A measure of the joint distribution of shorter and long run lengths with lower gray level values | |
| Short and Long Run High Gray Level Run Emphasis (SRHGLE and LRHGLE) | A measure of the joint distribution of shorter and long run lengths with higher gray level values | |
| Gray Level Size Zone Matrix (GLSZM) | Small and Large Area Emphasis (SAE and LAE) | A measure of the distribution of small and large size zones |
| Gray Level Non-Uniformity (GLN) and Gray Level Non-Uniformity Normalized (GLNN) | A measure of the variability of gray level intensity values in the image | |
| Size Zone Non-Uniformity (SZN) and Size Zone Non-Uniformity Normalized (SZNN) | A measure of the variability of size zone volumes in the image | |
| Zone Percentage (ZP) | A measure of the coarseness of the texture by taking the ratio of number of zones and number of voxels in the region of interest | |
| Gray Level Variance (GLV) | The variance in gray level intensities for the zones | |
| Zone Variance (ZV) | The variance in zone size volumes for the zones | |
| Zone Entropy (ZE) | A measure of the uncertainty/randomness in the distribution of zone sizes and gray levels | |
| Low and High Gray Level Zone Emphasis (LGLZE and HGLZE) | A measure of the distribution of lower and higher gray level size zones | |
| Small Area Low and High Gray Level Emphasis (SALGLE and SAHGLE) | A measure of the proportion in the image of the joint distribution of smaller size zones with lower and higher gray level values | |
| Large Area Low and High Gray Level Emphasis (LALGLE and LAHGLE) | A measure of the proportion in the image of the joint distribution of larger size zones with lower gray level values | |
| Neighboring Gray Tone Difference Matrix (NGTDM) | Coarseness | An average difference between the center voxel and its neighborhood and an indication of the spatial rate of change |
| Contrast | A measure of the spatial intensity change, also dependent on the overall gray level dynamic range | |
| Busyness | A measure of the change from a pixel to its neighbor | |
| Complexity | A measure of non-uniformity and rapid changes in gray levels | |
| Strength | A measure of the primitives in an image | |
| Gray Level Dependence Matrix (GLDM) | Small and Large Dependence Emphasis (SDE and LDE) | A measure of the distribution of small and large dependencies |
| Gray Level Non-Uniformity (GLN) | The similarity of gray level intensity values in the image | |
| Dependence Non-Uniformity (DN) and Dependence Non-Uniformity Normalized (DNN) | The similarity of dependence throughout the image | |
| Gray Level Variance | The variance in gray level in the image | |
| Dependence Variance | the variance in dependence size in the image | |
| Low and High Gray Level Emphasis (LGLE and HGLE) | The distribution of low and high gray level values | |
| Small and Large Dependence Low Gray Level Emphasis (SDLGLE and LDLGLE) | The joint distribution of small and large dependence with lower gray level values | |
| Small and Large Dependence High Gray Level Emphasis (SDHGLE and LDHGLE) | The joint distribution of small and large dependence with higher gray level values |