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read

Read data from randomPatchExtractionDatastore

Description

data = read(patchds) returns a batch of data from a random patch extraction datastore, patchds. Subsequent calls to the read function continue reading from the endpoint of the previous call.

[data,info] = read(patchds) also returns information about the extracted data, including metadata, in info.

Input Arguments

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Random patch extraction datastore, specified as a randomPatchExtractionDatastore object. The datastore specifies a MiniBatchSize number of observations in each batch, and a numObservations total number of observations.

Output Arguments

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Output data, returned as a table with MiniBatchSize number of rows.

  • The first variable is InputImage and contains input image patches.

  • If the network responses are images in an image datastore, then the second variable is ResponseImage.

  • If the network responses are pixel label images in a pixel label datastore, then the second variable is ResponsePixelLabelImage.

Each column contains a cell array of patches of size determined by PatchSize and the type of image data.

  • For 2-D single-channel images, the patches are size m-byn, where m specifies the number of rows and n specifies the number of columns in the patch.

  • For 2-D multi-channel images, the patches are size m-byn-by-c, where c specifies the number of color channels of the patch. c is 3 for RGB images.

  • For 3-D single-channel volumetric images, the patches are size m-byn-by-p, where p specifies the number of planes of the volume.

For the last batch of data in the datastore patchds, if numObservations is not cleanly divisible by MiniBatchSize, then read returns a partial batch containing all the remaining observations in the datastore.

Information about read data, returned as a structure array. The structure array can contain the following fields.

Field NameDescription
RandomPatchRectanglesMiniBatchSize-by-4 numeric matrix. Each row specifies the size and position of the patch in the format [xywidthheight]. The elements define the x- and y-coordinate of the top left corner, and the width and height of the patch.
ImageIndicesMiniBatchSize-by-1 numeric vector that specifies the indices of the read images in the input datastores.
InputImageFilenameMiniBatchSize-by-1 cell array that specifies the fully resolved path containing the path string, name of the file, and file extension of each input image.
ResponseImageFilenameMiniBatchSize-by-1 cell array that specifies the fully resolved path containing the path string, name of the file, and file extension of each response image or pixel label image.

Introduced in R2018b