Create a bigimage using a modified version of image "tumor_091.tif" from the CAMELYON16 data set. The original image is a training image of a lymph node containing tumor tissue. The original image has eight resolution levels, and the finest level has resolution 53760-by-61440. The modified image has only three coarse resolution levels. The spatial referencing of the modified image has been adjusted to enforce a consistent aspect ratio and to register features at each level.

bim = bigimage('tumor_091R.tif');

Display the entire bigimage at the finest resolution level. Display a grid of the block boundaries.

bshow = bigimageshow(bim,'GridVisible','on','GridLevel',1);

Determine the coarsest resolution level and the spatial referencing of the bigimage at that level.

clevel = bim.CoarsestResolutionLevel;
clevelLims = bim.SpatialReferencing(clevel);

Create a mask of the coarsest resolution level by following these steps:

imcoarse = getFullLevel(bim,clevel);
graycoarse = rgb2gray(imcoarse);
bwcoarse = imbinarize(graycoarse);
mask = imcomplement(bwcoarse);

Create a bigimage containing the mask. Use the same spatial referencing as the original big image.

bmask = bigimage(mask,'SpatialReferencing',clevelLims);

Display the mask.

figure
bigimageshow(bmask);

Overlay the mask on the original bigimage. To highlight all blocks that contain at least one nonzero mask pixel, specify an inclusion threshold of 0.

showmask(bshow,bmask,'InclusionThreshold',0);