mindspore.dataset.vision.LinearTransformation

class mindspore.dataset.vision.LinearTransformation(transformation_matrix, mean_vector)

Linearly transform the input numpy.ndarray image with a square transformation matrix and a mean vector.

It will first flatten the input image and subtract the mean vector from it, then compute the dot product with the transformation matrix, finally reshape it back to its original shape.

Parameters

• transformation_matrix (numpy.ndarray) – A square transformation matrix in shape of (D, D), where \(D = C \times H \times W\).

• mean_vector (numpy.ndarray) – A mean vector in shape of (D,), where \(D = C \times H \times W\).

Raises

• TypeError – If transformation_matrix is not of type numpy.ndarray.

• TypeError – If mean_vector is not of type numpy.ndarray.

Supported Platforms:

CPU

Examples

>>> import numpy as np
>>> from mindspore.dataset.transforms import Compose
>>>
>>> height, width = 32, 32
>>> dim = 3 * height * width
>>> transformation_matrix = np.ones([dim, dim])
>>> mean_vector = np.zeros(dim)
>>> transforms_list = Compose([vision.Decode(to_pil=True)),
...                            vision.Resize((height,width)),
...                            vision.ToTensor(),
...                            vision.LinearTransformation(transformation_matrix, mean_vector)])
>>> # apply the transform to dataset through map function
>>> image_folder_dataset = image_folder_dataset.map(operations=transforms_list,
...                                                 input_columns="image")

execute_py(np_img)

Execute method.

Parameters

np_img (numpy.ndarray) – Image in shape of (C, H, W) to be linearly transformed.

Returns

numpy.ndarray, linearly transformed image.