Module imagingbook.common
Package imagingbook.common.image

Class IntegralImage

java.lang.Object
imagingbook.common.image.IntegralImage
public class IntegralImage extends Object

This class represents an 'integral image' or 'summed area table' as proposed in [1], See Sec. 2.8 of [2] for a detailed description. Currently only implemented for images of type ByteProcessor.

[1] F. C. Crow. Summed-area tables for texture mapping. SIGGRAPH, Computer Graphics 18(3), 207–212 (1984).
[2] W. Burger, M.J. Burge, Digital Image Processing – An Algorithmic Introduction, 3rd ed, Springer (2022).

Version:
2022/07/11

  • Constructor Summary

    Constructors
    Constructor
    Description
    IntegralImage(int[][] I)
    Constructor, creates a new IntegralImage instance from pixel values in a 2D int-array I[x][y].
    IntegralImage(ByteProcessor I)
    Constructor, creates a new IntegralImage instance from pixel values in the specified ByteProcessor.

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    getBlockSum1(int ua, int va, int ub, int vb)
    Calculates the sum of the pixel values in the rectangle R, specified by the corner points a = (ua, va) and b = (ub, vb).
    long
    getBlockSum2(int ua, int va, int ub, int vb)
    Calculates the sum of the squared pixel values in the rectangle R, specified by the corner points a = (ua, va) and b = (ub, vb).
    double
    getMean(int ua, int va, int ub, int vb)
    Calculates the mean of the image values in the specified rectangle.
    long[][]
    getS1()
    Returns the summed area table of pixel values (Σ1).
    long[][]
    getS2()
    Returns the summed area table of squared pixel values (Σ2).
    int
    getSize(int ua, int va, int ub, int vb)
    Returns the size of (number of pixels in) the specified rectangle.
    double
    getVariance(int ua, int va, int ub, int vb)
    Calculates the variance of the image values in the specified rectangle.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

  • Method Details

    • getS1

      public long[][] getS1()
      Returns the summed area table of pixel values (Σ1).
      Returns:
      array of Σ1 values

    • getS2

      public long[][] getS2()
      Returns the summed area table of squared pixel values (Σ2).
      Returns:
      array of Σ2 values

    • getBlockSum1

      public long getBlockSum1(int ua, int va, int ub, int vb)
      Calculates the sum of the pixel values in the rectangle R, specified by the corner points a = (ua, va) and b = (ub, vb).
      Parameters:
      ua - leftmost position in R
      va - top position in R
      ub - rightmost position in R
      vb - bottom position in R
      Returns:
      the first-order block sum (S1(R)) inside the specified rectangle or zero if the rectangle is empty.

    • getBlockSum2

      public long getBlockSum2(int ua, int va, int ub, int vb)
      Calculates the sum of the squared pixel values in the rectangle R, specified by the corner points a = (ua, va) and b = (ub, vb).
      Parameters:
      ua - leftmost position in R
      va - top position in R
      ub - rightmost position in R
      vb - bottom position in R
      Returns:
      the second-order block sum (S2(R)) inside the specified rectangle or zero if the rectangle is empty.

    • getSize

      public int getSize(int ua, int va, int ub, int vb)
      Returns the size of (number of pixels in) the specified rectangle.
      Parameters:
      ua - leftmost position in R
      va - top position in R
      ub - rightmost position in R (ub >= ua)
      vb - bottom position in R (vb >= va)
      Returns:
      the size of the specified rectangle

    • getMean

      public double getMean(int ua, int va, int ub, int vb)
      Calculates the mean of the image values in the specified rectangle.
      Parameters:
      ua - leftmost position in R
      va - top position in R
      ub - rightmost position in R (ub >= ua)
      vb - bottom position in R (vb >= va)
      Returns:
      the mean value for the specified rectangle

    • getVariance

      public double getVariance(int ua, int va, int ub, int vb)
      Calculates the variance of the image values in the specified rectangle. parameters.
      Parameters:
      ua - leftmost position in R
      va - top position in R
      ub - rightmost position in R (u1 >= u0)
      vb - bottom position in R (v1 >= v0)
      Returns:
      the variance for the specified rectangle