Main Content

sub2world

Convert pixel subscripts to block subscripts

collapse all in page

Syntax

world = sub2world(bim,pixelsub)
world = sub2world(bim,pixelsub,'Level',L)

Description

example

world = sub2world(bim,pixelsub) converts the pixel subscripts, pixelsub, to the block subscript of the block containing the corresponding pixel.

world = sub2world(bim,pixelsub,'Level',L) additionally specifies the resolution level to use in a multiresolution image. Level defaults to 1.

Examples

collapse all

Open Live Script

Convert pixel subscripts from one level to another via the world coordinates to refer to the same spatial region.

Create a blocked image from a sample image included with the toolbox.

bim = blockedImage('tumor_091R.tif');

Define a region of interest in the finest resolution level in pixel subscripts.

level1PixelSubStart = [1700, 1550 1];
level1PixelSubEnd = [2100, 2000 3];

Get the image data from the region of interest on the resolution level 1 image.

imr = getRegion(bim, level1PixelSubStart, level1PixelSubEnd, "Level", 1);
size(imr)
ans = 1×3

   401   451     3

Convert the pixel subscripts that define the region of interest into world coordinates. By default, sub2world converts the coordinates at level 1, the finest resolution.

worldRegion = sub2world(bim,[level1PixelSubStart; level1PixelSubEnd]);

Compute a binary mask at the coarsest level.

bbw = apply(bim, @(bs)imbinarize(im2gray(bs.Data)), "Level", 3);

Convert the world coordinates of the region of interest to pixel subscripts of the mask. Note that the mask has only two dimensions.

worldRegion = worldRegion(:,1:2);
maskPixelSubs = world2sub(bbw,worldRegion);

Corresponding mask region.

bwr = getRegion(bbw, maskPixelSubs(1,:), maskPixelSubs(2,:));
size(bwr)
ans = 1×2

    51    58

View the original image and the mask.

montage({imr,bwr})

Figure contains an axes object. The axes object contains an object of type image.

Input Arguments

collapse all

Blocked image, specified as a blockedImage object.

Pixel subscripts, specified as a K-by-N integer-valued vector, where N is the number of dimensions and K is the number of coordinates.

Output Arguments

collapse all

World subscripts, returned as a K-by-X numeric array. The world coordinates are in the same order as the pixel subscripts. For an N-dimensional blockedImage, and K subscripts (each row is a separate subscript), pixelsub is a K-by-N integer-valued matrix and world is a K-by-N numeric matrix.

Version History

Introduced in R2021a

See Also

|