setBlock

(Removed) Put data in specific block of bigimage object

The setBlock function of the bigimage object has been removed (since R2026a). Use the setBlock function associated with the blockedImage object instead. For more information, see Version History.

Syntax

setBlock(bigimg,level,locationWorld,data)

Description

setBlock(bigimg,level,locationWorld,data) sets the pixel data in the block of big image bigimg that contains coordinate locationWorld at the specified resolution level.

example

Examples

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Set Blocks of Writable Big Image

Create a bigimage from the sample image "tumor_091R.tif".

bim = bigimage("tumor_091R.tif");

Display the bigimage, then create a circle ROI over the displayed image.

h = bigimageshow(bim);
hROI = drawcircle(gca,'Radius',470,'Position',[1477 2284]);

Choose the level at which to create a writable bigimage. Level 3 is the coarsest resolution level.

maskLevel = 3;

Get the spatial referencing and pixel extents from the specified level.

ref = bim.SpatialReferencing(maskLevel);
pixelExtent = [ref.PixelExtentInWorldX,ref.PixelExtentInWorldY];

Create a writable bigimage by specifying the spatial referencing instead of image data. This big image has one channel and is of data type logical.

bmask = bigimage(ref,1,"logical");

Loop through all blocks in the writable big image to create a mask image. For each block, set the pixel values as 1 (true) for pixels inside the ROI and 0 (false) for pixels outside the ROI.

for cStart = 1:bmask.BlockSize(2):ref.ImageSize(2)
    for rStart = 1:bmask.BlockSize(1):ref.ImageSize(1)

        % Get the center of top left pixel of this block in world units.
        xyStart = [cStart,rStart].*pixelExtent;

        % Get the block size. The 'BlockSize' property represents the
        % size as a 2-element vector of the form [row,column]. Switch the
        % order of the elements so that the block size is represented as
        % [x,y].
        bsize = bmask.BlockSize;
        numRows = bsize(1);
        numCols = bsize(2);

        % Determine which pixels have coordinates inside the ROI.
        roiPositions = hROI.Vertices;

        % Transform |roiPositions| from world coordinates to the intrinsic
        % image indices at the given resolution level.
        roiPositions = (roiPositions - xyStart) ./ pixelExtent + 1;

        blockMask = poly2mask(roiPositions(:,1),roiPositions(:,2), ...
                              numRows, numCols);

        % Set the pixel values of the block.
        setBlock(bmask,1,xyStart,blockMask);
    end
end

Display the mask.

bigimageshow(bmask)

Input Arguments

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`bigimg` — Big image
`bigimage` object

Big image, specified as a bigimage object.

`level` — Resolution level
positive integer

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

`locationWorld` — Coordinate of a point
1-by-2 numeric vector

Coordinate of a point, specified as a 1-by-2 numeric vector of the form [x y]. The location is specified in world coordinates, which are the pixel locations relative to the highest resolution level. The position must be a valid position within bigimg.

`data` — Pixel data
numeric array

Pixel data, specified as a numeric array of the same data type as the big image, bigimg.ClassUnderlying. The first two dimensions of the data must match the block size at the specified level.

Tips

Create a writable bigimage by using a syntax that does not initialize image data. If you create a bigimage by specifying the file name, directory name, or variable name of image data, or by using the apply function, then the bigimage is not writable and you cannot use the setBlock function.
If the size of data is less than the block size bigimg.BlockSize, then setBlock pads the data with the default value, bigimg.UnloadedValue.
setBlock trims data for partial edge blocks.

Version History

Introduced in R2019b

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R2026a: Removed

The setBlock function has been removed. Use the setBlock function of the blockedImage object instead.

Code Updates

To update your code, first create a writable blockedImage object to which you can write image data. Then, follow these steps:

Convert from (x, y) world coordinates to (row, column) world coordinates by switching the order of the two elements.
Convert the world coordinates to pixel subscripts using the world2sub function. If you want to set the block at a resolution level other than level 1, then specify that level by using the Level name-value argument.
Convert the pixel subscripts to block subscripts using the sub2blocksub function. If you want to set the block at a resolution level other than level 1, then specify that level by using the Level name-value argument.
The blockedImage setBlock function requires the size of the data to be equal to the block size. If you want to set blockedImage data of size smaller than the block size, then you can pad the data.
Pass the blocked image, the block subscript, and the data to write to the setBlock function. If you want to set the block at a resolution level other than level 1, then specify that level by using the Level name-value argument.
After you are done writing data to the blockedImage object, then you must change the mode of the object to read-only before getting the image data. For example, change the mode of blockedImage object blockedMask by setting the Mode property to "r" using dot notation:
```
blockedMask.Mode = "r";
```
In contrast, you can read written data from a bigimage object without changing the object properties.

Removed Recommended

Removed	Recommended
This example uses the `setBlock` function with a `bigimage` object to set the image data in the block surrounding world (x, y) coordinates (1000, 2500) at the highest resolution level. % Create a writable bigimage object filename = "tumor_091R.tif"; bim = bigimage(filename); ref = bim.SpatialReferencing(1); blockSize = bim.BlockSize(1,1:2); bigMask = bigimage(ref,1,"logical"); % Identify a coordinate coordWorld = [1000 2500]; % Specify the data to write, then write the data blockSize = bim.BlockSize(1,1:2); data = logical(checkerboard(blockSize(1)/16,8)); setBlock(bigMask,1,coordWorld,data);	Here is equivalent code using a `blockedImage` object. % Create a writable blockedImage object filename = "tumor_091R.tif"; blockedIm = blockedImage(filename); imgSize = blockedIm.Size(1,1:2); blockSize = blockedIm.BlockSize(1,1:2); initVal = logical(0); blockedMask = blockedImage([],imgSize,blockSize,initVal,Mode="w"); % Identify the block containing a coordinate coordWorld = [1000 2500]; coordRC = flip(coordWorld); subPixel = world2sub(blockedMask,coordRC); subBlock = sub2blocksub(blockedMask,subPixel); % Specify the data to write, then write the data to the block data = logical(checkerboard(blockSize(1)/16,8)); setBlock(blockedMask,subBlock,data);
This example uses the `setBlock` function with a `bigimage` object to set image data of a size smaller than the block size. % Create a writable bigimage object % (same as above) % Identify a coordinate % (same as above) % Specify the data to write, then write the data data = logical(checkerboard(10,8)); setBlock(bmask,1,coordWorld,data);	Here is equivalent code using a `blockedImage` object. % Create a writable blockedImage object % (same as above) % Identify a coordinate % (same as above) % Specify the data to write, then write the data to the block data = logical(checkerboard(10,8)); data = padarray(data,blockSize-size(data),initVal,"post"); setBlock(blockedMask,subBlock,data);

This example uses the setBlock function with a bigimage object to set the image data in the block surrounding world (x, y) coordinates (1000, 2500) at the highest resolution level.

% Create a writable bigimage object
filename = "tumor_091R.tif";
bim = bigimage(filename);
ref = bim.SpatialReferencing(1);
blockSize = bim.BlockSize(1,1:2);
bigMask = bigimage(ref,1,"logical");

% Identify a coordinate
coordWorld = [1000 2500];

% Specify the data to write, then write the data
blockSize = bim.BlockSize(1,1:2);
data = logical(checkerboard(blockSize(1)/16,8));
setBlock(bigMask,1,coordWorld,data);

Here is equivalent code using a blockedImage object.

% Create a writable blockedImage object
filename = "tumor_091R.tif";
blockedIm = blockedImage(filename);
imgSize = blockedIm.Size(1,1:2);
blockSize = blockedIm.BlockSize(1,1:2);
initVal = logical(0);
blockedMask = blockedImage([],imgSize,blockSize,initVal,Mode="w");

% Identify the block containing a coordinate
coordWorld = [1000 2500];
coordRC = flip(coordWorld);
subPixel = world2sub(blockedMask,coordRC);
subBlock = sub2blocksub(blockedMask,subPixel);

% Specify the data to write, then write the data to the block
data = logical(checkerboard(blockSize(1)/16,8));
setBlock(blockedMask,subBlock,data);

This example uses the setBlock function with a bigimage object to set image data of a size smaller than the block size.

% Create a writable bigimage object
% (same as above)
% Identify a coordinate
% (same as above)

% Specify the data to write, then write the data
data = logical(checkerboard(10,8));
setBlock(bmask,1,coordWorld,data);

Here is equivalent code using a blockedImage object.

% Create a writable blockedImage object
% (same as above)
% Identify a coordinate
% (same as above)

% Specify the data to write, then write the data to the block
data = logical(checkerboard(10,8));
data = padarray(data,blockSize-size(data),initVal,"post");
setBlock(blockedMask,subBlock,data);

R2024b: Warns

The setBlock function issues a warning that it will be removed in a future release.

R2023b: To be removed

The bigimage object and this function will be removed in a future release.

R2021a: Not recommended

The setBlock function of the bigimage object is not recommended. Use the setBlock function of the blockedImage object instead. The blockedImage object offers several advantages including extension to N-D processing, a simpler interface, and custom support for reading and writing nonstandard image formats.