qtgetblk (Image Processing Toolbox)

Get block values in quadtree decomposition

Syntax

[vals,r,c] = qtgetblk(I,S,dim)
[vals,idx] = qtgetblk(I,S,dim)

Description

[vals,r,c] = qtgetblk(I,S,dim) returns in vals an array containing the dim-by-dim blocks in the quadtree decomposition of I. S is the sparse matrix returned by qtdecomp; it contains the quadtree structure. vals is a dim-by-dim-by-k array, where k is the number of dim-by-dim blocks in the quadtree decomposition; if there are no blocks of the specified size, all outputs are returned as empty matrices. r and c are vectors containing the row and column coordinates of the upper-left corners of the blocks.

[vals,idx] = qtgetblk(I,S,dim) returns in idx a vector containing the linear indices of the upper-left corners of the blocks.

Class Support

I can be of class logical, uint8, uint16, or double. S is of class sparse.

Remarks

The ordering of the blocks in vals matches the columnwise order of the blocks in I. For example, if vals is 4-by-4-by-2, vals(:,:,1) contains the values from the first 4-by-4 block in I, and vals(:,:,2) contains the values from the second 4-by-4 block.

Example

This example continues the qtdecomp example.

[vals,r,c] = qtgetblk(I,S,4) 
 
vals(:,:,1) =
 
     1     1     1     1
     1     1     2     1
     1     1     1     1
     1     1     1     1
 
 
vals(:,:,2) =
 
    20    22    20    22
    20    22    22    20
    20    22    20    20
    22    22    20    20
 
 
r =
 
     1
     5


c =
 
     1
     1

See Also

qtdecomp, qtsetblk

qtdecomp qtsetblk