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--- interimage:attributes_description [2010/06/23 14:33] – castejon
+++ interimage:attributes_description [2010/06/23 20:08] – hermann
@@ Linha 33: / Linha 33: @@
 ===== Shape Attributes =====
-  * area: Returns the area of the given polygon, in number of pixels.
+  * **area**: Returns the area of the given polygon, in number of pixels.
-  * bBoxArea: Returns the bounding box area of the given polygon, in number of pixels.
+  * **bBoxArea**: Returns the bounding box area of the given polygon, in number of pixels.
-  * perimeter: Returns the perimeter of the polygon, considering the amount of pixels in its border.
+  * **perimeter**: Returns the perimeter of the polygon, considering the amount of pixels in its border.
-  * fractalDimension: Returns the fractal dimension of a given polygon, which is calculated by the following equation:
+  * **fractalDimension**: Returns the fractal dimension of a given polygon, which is calculated by the following equation:
 {{ :interimage:fractal.png }}
 Where P is the polygon perimeter and A is the area.
-  * perimeterAreaRatio: Calculates the ratio between the perimeter and the area of a polygon.
+  * **perimeterAreaRatio**: Calculates the ratio between the perimeter and the area of a polygon.
-  * compacity: Returns the compacity of a given polygon, which is calculated by the following equation:
+  * **compacity**: Returns the compacity of a given polygon, which is calculated by the following equation:
 {{ :interimage:compacity.png }}
 Where P is the polygon perimeter and A is the area.
-  * density: The density of a polygon is calculated by the ratio between its area and its Radius (the maximum distance between the polygon centroid and all its vertices).
+  * **density**: The density of a polygon is calculated by the ratio between its area and its Radius (the maximum distance between the polygon centroid and all its vertices).
-  * length: The Length of a polygon is the height of its bounding box.
+  * **length**: The Length of a polygon is the height of its bounding box.
-  * width: The Width of a polygon is calculated by the width of its bounding box.
+  * **width**: The Width of a polygon is calculated by the width of its bounding box.
-  * contiguity: Contiguity index assesses the spatial connectedness of pixels within a polygon to provide an index of boundary configuration.
+  * **contiguity**: Contiguity index assesses the spatial connectedness of pixels within a polygon to provide an index of boundary configuration.
-  * gyrationRadius: This attribute equals the mean distance between each pixel in the polygon and the polygon centroid.
+  * **gyrationRadius**: This attribute equals the mean distance between each pixel in the polygon and the polygon centroid.
-  * angle: The main angle of a polygon. It is obtained by calculating the best elliptic fit, and the angle of the bigest radius of the ellipse corresponds to the polygon angle.
+  * **angle**: The main angle of a polygon. It is obtained by calculating the best elliptic fit, and the angle of the biggest radius of the ellipse corresponds to the polygon angle.
-  * ellipticFit: Finds the best ellipse which fits outside the polygon and returns the ratio between the polygon area and the ellipse area.
+  * **ellipticFit**: Finds the best ellipse which fits outside the polygon and returns the ratio between the polygon area and the ellipse area.
-  * squareness: This attribute fits the minimum rectangle outside the polygon and calculates the ratio between the polygon area and the area of this rectangle. The most close to 1 is this attribute, the most similar to a rectangle the polygon is.
+  * **squareness**: This attribute fits the minimum rectangle outside the polygon and calculates the ratio between the polygon area and the area of this rectangle. The t closest to 1 is this attribute, the most similar to a rectangle the polygon is.
-  * circleness: It is calculated by the following equation:
+  * **circleness**: It is calculated by the following equation:
 {{ :interimage:circle.png }}
 Where A is the polygon area and R is the maximum distance between the polygon centroid and all its vertices.
-  * shapeIndex: Returns the shape index of a given polygon, which is calculated by the following equation:
+  * **shapeIndex**: Returns the shape index of a given polygon, which is calculated by the following equation:
  {{ :interimage:shapeindex.png }}
 Where P is the polygon perimeter and A is the area.
@@ Linha 66: / Linha 67: @@
 ===== Spectral Statistical Attributes =====
-  * **Amplitude** -
+  * **Amplitude** - represents the difference between the maximum and minimum pixel values of a region for the given image band/channel.
   * **Brightness** -
-  * **Correlation** - Correlation is a similarity measures between two data sets under an absolute scale between [-1,1]. It is calculated as showed by the next formula:
+  * **Correlation** - Correlation is a similarity measure between two data sets under an absolute scale between [-1,1]. It is calculated as showed by the next formula:
 {{ interimage:att_correlation.gif }}
@@ Linha 101: / Linha 102: @@
   * **Variance** - Like the standart deviation, the variance also represents the numerical data dispersion degree surrounding the mean but in the original data values scale. It is defined by:
 {{ interimage:att_variance.gif }}
@@ Linha 122: / Linha 128: @@
 {{ interimage:att_dissimilarityglcm.gif }}
-  * **EntropyGLCM** -
+  * **EntropyGLCM** - Like the simple statistical entropy the GLCM entropy also is a statistical measure of image data randomness. The difference is that it uses frequencies of gray levels co-ocurrences instead of using point values frequencies. The co-ocurrences matrix is used and the calculus is showed by the next formula where "i" and "j" are adjacent image points values under one pre-defined direction. p(i,j) is the probability of that co-ocurrence over the image.
+{{ interimage:att_entropyglcm.gif }}
-  * **HomogeneityGLCM** -
+  * **HomogeneityGLCM** - Returns a value representing the distance between the distribuition of co-ocurrence matrix elements and those diagonal elements. The returned values range is between [0,1]. For images with low values variation the returned value will be near to zero. The calculus is showed by the next formula where "i" and "j" are adjacent image points values under one pre-defined direction. p(i,j) is the probability of that co-ocurrence over the image.
+{{ interimage:att_homogeneityglcm.gif }}
-  * **MeanGLCM** -
+  * **MeanGLCM** - The GLCM mean value is expressed in function of the frequency of co-ocorrence of image elements related to their neighborhood under one pre-defined direction. The calculus is showed by the next formula where "i" and "j" are adjacent image points values under one pre-defined direction. p(i,j) is the probability of that co-ocurrence over the image.
+{{ interimage:att_meanglcm.gif }}
-  * **QuiSquareGLCM** -
+  * **QuiSquareGLCM** - This metric can be understood as a form of energy normalization expressed in function of the linear dependency gray levels for image elements. The calculus is showed by the next formulas where "i" and "j" are adjacent image points values under one pre-defined direction. p(i,j) is the probability of that co-ocurrence over the image. Pj is the marginal probability for that co-ocurrence.
+{{ interimage:att_quisquareglcm_1.gif }}
+{{ interimage:att_quisquareglcm_2.gif }}
+{{ interimage:att_quisquareglcm_3.gif }}
-  * **StdDeviationGLCM** -
+  * **StdDeviationGLCM** - The standart deviation is a measure that represents the values dispersion around a GLCM mean value. The GLCM standart deviation calcule differs from the simple standart deviation because the use of co-ocurrence frequencies. The calculus is showed by the next formula where "i" and "j" are adjacent image points values under one pre-defined direction. p(i,j) is the probability of that co-ocurrence over the image.
+{{ interimage:att_stddeviationglcm.gif }}
 ===== Neighborhood Attributes =====
@@ Linha 148: / Linha 161: @@
   * **meanDiffToNeighbors** - mean difference of the layer **L** mean value of an image object to the layer **L** mean value of direct neighbors (**R**=0) or all neighbor objects inside the range **R** (**R**>0). The differences are weighted with regard to the shared border (**R**=0) or the area covered by the neighbor objects inside the range (**R**>0). The distance between the image object and its neighbors is calculated considering their centroids.