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Convert pixel subscripts to block subscripts

Since R2021a



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 L to use in a multiresolution image.


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Convert pixel subscripts from one level to another via the world coordinates.

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

bim = blockedImage("tumor_091R.tif");

Create a binary mask at the coarsest resolution level.

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

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

pixelStartLevel1 = [1700 1550];
pixelEndLevel1 = [2100 2000];
imagePixelSubs = [pixelStartLevel1; pixelEndLevel1];

Get the image data from the ROI at the finest resolution level.

roiImage = getRegion(bim,pixelStartLevel1,pixelEndLevel1,Level=1);
ans = 1×3

   401   451     3

Convert the pixel subscripts that define the ROI into world coordinates. By default, sub2world converts the coordinates at the finest resolution level.

worldRegion = sub2world(bim,imagePixelSubs);

Convert the world coordinates of the ROI to pixel subscripts of the mask.

maskPixelSubs = world2sub(bmask,worldRegion);

Get the mask data from the ROI.

roiMask = getRegion(bmask,maskPixelSubs(1,:),maskPixelSubs(2,:));
ans = 1×2

    51    58

View the region of interest and the corresponding mask.


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

Input Arguments

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Blocked image, specified as a blockedImage object.

Pixel subscripts, specified as a K-by-N integer-valued vector, where K is the number of pixels. N is equal to or less than the number of dimensions of the blocked image bim. For example, you can exclude a color channel from the conversion by specifying the pixel subscripts with one less dimension than the blocked image.

Resolution level, specified as a positive integer that is less than or equal to the number of resolution levels of bim.

Output Arguments

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World coordinates, returned as a K-by-N numeric array, where K is the number of pixels and N is the dimensionality of the coordinates.

Version History

Introduced in R2021a

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