mmagic.datasets.transforms.fgbg

Augmentation on foreground and background.

Module Contents

Classes

CompositeFg	Composite foreground with a random foreground.
MergeFgAndBg	Composite foreground image and background image with alpha.
PerturbBg	Randomly add gaussian noise or gamma change to background image.
RandomJitter	Randomly jitter the foreground in hsv space.
RandomLoadResizeBg	Randomly load a background image and resize it.

class mmagic.datasets.transforms.fgbg.CompositeFg(fg_dirs, alpha_dirs, interpolation='nearest')

Bases: mmcv.transforms.BaseTransform

Composite foreground with a random foreground.

This class composites the current training sample with additional data randomly (could be from the same dataset). With probability 0.5, the sample will be composited with a random sample from the specified directory. The composition is performed as:

\[ \begin{align}\begin{aligned}fg_{new} = \alpha_1 * fg_1 + (1 - \alpha_1) * fg_2\\\alpha_{new} = 1 - (1 - \alpha_1) * (1 - \alpha_2)\end{aligned}\end{align} \]

where \((fg_1, \alpha_1)\) is from the current sample and \((fg_2, \alpha_2)\) is the randomly loaded sample. With the above composition, \(\alpha_{new}\) is still in [0, 1].

Required keys are “alpha” and “fg”. Modified keys are “alpha” and “fg”.

Parameters

• fg_dirs (str | list[str]) – Path of directories to load foreground images from.

• alpha_dirs (str | list[str]) – Path of directories to load alpha mattes from.

• interpolation (str) – Interpolation method of mmcv.imresize to resize the randomly loaded images. Default: ‘nearest’.

transform(results: dict) → dict

Transform function.

Parameters

results (dict) – A dict containing the necessary information and data for augmentation.

Returns

A dict containing the processed data and information.

Return type

dict

_get_file_list(fg_dirs, alpha_dirs)

__repr__()

Return repr(self).

class mmagic.datasets.transforms.fgbg.MergeFgAndBg

Bases: mmcv.transforms.BaseTransform

Composite foreground image and background image with alpha.

Required keys are “alpha”, “fg” and “bg”, added key is “merged”.

transform(results: dict) → dict

Transform function.

Parameters

results (dict) – A dict containing the necessary information and data for augmentation.

Returns

A dict containing the processed data and information.

Return type

dict

__repr__() → str

Return repr(self).

class mmagic.datasets.transforms.fgbg.PerturbBg(gamma_ratio=0.6)

Bases: mmcv.transforms.BaseTransform

Randomly add gaussian noise or gamma change to background image.

Required key is “bg”, added key is “noisy_bg”.

Parameters

gamma_ratio (float, optional) – The probability to use gamma correction instead of gaussian noise. Defaults to 0.6.

transform(results: dict) → dict

Transform function.

Parameters

results (dict) – A dict containing the necessary information and data for augmentation.

Returns

A dict containing the processed data and information.

Return type

dict

__repr__()

Return repr(self).

class mmagic.datasets.transforms.fgbg.RandomJitter(hue_range=40)

Bases: mmcv.transforms.BaseTransform

Randomly jitter the foreground in hsv space.

The jitter range of hue is adjustable while the jitter ranges of saturation and value are adaptive to the images. Side effect: the “fg” image will be converted to np.float32. Required keys are “fg” and “alpha”, modified key is “fg”.

Parameters

hue_range (float | tuple[float]) – Range of hue jittering. If it is a float instead of a tuple like (min, max), the range of hue jittering will be (-hue_range, +hue_range). Default: 40.

transform(results)

transform function.

Parameters

results (dict) – A dict containing the necessary information and data for augmentation.

Returns

A dict containing the processed data and information.

Return type

dict

__repr__()

Return repr(self).

class mmagic.datasets.transforms.fgbg.RandomLoadResizeBg(bg_dir, flag='color', channel_order='bgr')

Bases: mmcv.transforms.BaseTransform

Randomly load a background image and resize it.

Required key is “fg”, added key is “bg”.

Parameters

• bg_dir (str) – Path of directory to load background images from.

• flag (str) – Loading flag for images. Default: ‘color’.

• channel_order (str) – Order of channel, candidates are ‘bgr’ and ‘rgb’. Default: ‘bgr’.

• kwargs (dict) – Args for file client.

transform(results: dict) → dict

Transform function.

Parameters

results (dict) – A dict containing the necessary information and data for augmentation.

Returns

A dict containing the processed data and information.

Return type

dict

__repr__()

Return repr(self).