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blocksub2sub

Convert block subscripts to pixel subscripts

    Description

    example

    [pStart,pEnd] = blocksub2sub(bim,blocksub) converts a block subscript to pixel subscripts. pStart is the pixel subscripts of the first pixel in the block. pEnd is the pixel subscripts of the last pixel in the block. Note: For partial blocks pEnd represents the last valid pixel subscript in the image.

    [pStart,pEnd] = blocksub2sub(bim,blocksub,'Level',L) additionally specifies the resolution level to use in a multiresolution image. Level defaults to 1.

    Examples

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    Create a small sample image as a 5-by-7 matrix of zeros. Here is an illustration of the small sample image, with the pixel coordinates of the four corners provided.

    Create a blocked image from the sample image, specifying a 2-by-2 block size. To create this blocked image, use blockedImage in write mode.

    bim = blockedImage([], [5 7], [2 2], uint8(0), "Mode", 'w');

    Here is an illustration of the blocked image overlaid on the original image. It is divided into 2-by-2 blocks. In the diagram, each block contains it's block coordinates.

    Convert block subscripts into pixel subscripts by using the blocksub2sub function. By default, if the image is a multiresolution image, blocksub2sub uses pixel coordinates from coarest level, although you can specify any level. Since the sample image has only one resolution level, blocksub2sub converts level 1.

    [pstart pend] = blocksub2sub(bim,[2 3])
    pstart = 1×2
    
         3     5
    
    
    pend = 1×2
    
         4     6
    
    

    This illustration show the block coordinate [2 3] converted to pixel coordinates.

    Input Arguments

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    Blocked image, specified as a blockedImage object.

    Block subscripts, specified as a numeric array.

    Example: [2 3]

    Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical

    Output Arguments

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    Subscript of first pixel in the specified block, returned as a numeric array.

    Subscript of last pixel in the specified block, returned as a numeric array.

    See Also

    Introduced in R2021a