Documentation for all Available Warping Transformations¶
BarrelDistortion ¶
Bases: WarpTransform
Applies a barrel distortion effect by distorting the radial distance from the center using a polynomial approximation.
Note: We use an an approximation of the polynomial radial distortion model to invert the original barrel formulas. see https://stackoverflow.com/questions/6199636/formulas-for-barrel-pincushion-distortion
Transformation
r' = r * (1 + strength * r^2)
x' = r' * cos(theta)
y' = r' * sin(theta)
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the barrel distortion effect. |
0.5
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the barrel distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Bulge ¶
Bases: WarpTransform
Applies a bulge distortion effect by radially distorting the coordinates outward.
Transformation
r' = r^strength
x' = r' * cos(theta)
y' = r' * sin(theta)
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the bulge distortion effect. Must be greater than or equal to 1.0. |
1.0
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the bulge distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Compression ¶
Bases: Stretching
Applies a compression effect along the specified axis.
Transformation
x' = x * (1 + strength) (if axis = 'horizontal')
y' = y * (1 + strength) (if axis = 'vertical')
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the stretching effect. Should be >=0. |
0.5
|
axis |
str
|
The axis along which to apply the stretching effect ('horizontal' or 'vertical'). |
'horizontal'
|
Fisheye ¶
Bases: WarpTransform
Applies a fisheye distortion effect by stretching the magnitude of the coordinates based on a power function.
Transformation
r' = r^{1 + strength}
x' = r' cos(theta)
y' = r' sin(theta)
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the distorsion. Identity function for strenght = 0.0. |
0.5
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the fisheye distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Implosion ¶
Bases: Bulge
Applies an implosion distortion effect by radially distorting the coordinates inward.
Transformation
r' = r^strength
x' = r' * cos(theta)
y' = r' * sin(theta)
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the implosion distortion effect. Must be between 0.0 and 1.0. |
0.5
|
Perspective ¶
Bases: WarpTransform
pylint: disable=C0301¶
Applies a random perspective wrap as defined here: https://pytorch.org/vision/main/_modules/torchvision/transforms/transforms.html#RandomPerspective https://pytorch.org/vision/main/_modules/torchvision/transforms/functional.html#perspective
Transformation
Picks random end points for perspective warp and uses current corners as start points to generate the warping matrix. Given the warping coefficients (a, b, c, d, e, f, g, h) we have the following association:
x' = (ax + by + c) / (gx + hy + 1)
y' = (dx + ey + f) / (gx + hy + 1)
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the perspective distortion effect. |
0.5
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the shear distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Pinch ¶
Bases: WarpTransform
Applies a pinch distortion effect by pinching it towards the user.
Transformation
pinch_factor = sin(pi/2 * r)^(-strength)
x' = x' * pinch_factor
y' = y' * pinch_factor
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the pinch distortion effect. Must be between 0.0 and 1.0. |
0.5
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the pinch distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Pincushion ¶
Bases: BarrelDistortion
Applies a pincushion distortion effect, which is the inverse of barrel distortion.
Transformation
r' = r * (1 - strength * r^2)
x' = r' * cos(theta)
y' = r' * sin(theta)
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the pincushion distortion effect. |
0.5
|
Punch ¶
Bases: Pinch
Applies a punch distortion effect which is opposite of pinch and pushes image away from the user.
Transformation
punch_factor = sin(pi/2 * r)^(strength)
x' = x' * punch_factor
y' = y' * punch_factor
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the punch distortion effect. Must be between 0.0 and 1.0. |
0.5
|
Shear ¶
Bases: WarpTransform
Applies a shear distortion effect. Implemented as defined here: https://en.wikipedia.org/wiki/Shear_mapping
Transformation
x' = x + strength*y (if axis = 'horizontal')
y' = strength*x + y (if axis = 'vertical')
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the shear distortion effect. Also defined as the cotangent of the shear angle. Positive for right/top leaning, negative for left/bottom leaning shear. |
0.5
|
axis |
The axis along which to apply the shearing effect ('horizontal' or 'vertical'). |
'horizontal'
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the shear distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Spherize ¶
Bases: WarpTransform
Applies a spherical distortion effect by mapping the coordinates onto a sphere.
Transformation
r' = sin(r * strength * pi/2) / (strength * pi/2)
x' = r' * cos(theta)
y' = r' * sin(theta)
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the spherical distortion effect. |
0.5
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the spherize distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Stretching ¶
Bases: WarpTransform
Applies a stretching effect along the specified axis.
Transformation
x' = x * (1 - strength) (if axis = 'horizontal')
y' = y * (1 - strength) (if axis = 'vertical')
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the stretching effect. |
0.5
|
axis |
str
|
The axis along which to apply the stretching effect ('horizontal' or 'vertical'). |
'horizontal'
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the stretching distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Swirl ¶
Bases: WarpTransform
Applies a swirl distortion effect by rotating the coordinates around the center based on their radial distance from the center.
Transformation
theta' = theta + (radius - r) * strength
x' = r' * cos(theta')
y' = r' * sin(theta')
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the swirl effect. Higher values result in a stronger swirl. |
1.0
|
radius |
float
|
The maximum distance from the center where the swirl effect is applied. |
1.0
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the swirl distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Twirl ¶
Bases: WarpTransform
Applies a twirl distortion effect by rotating the coordinates around the center with an angle proportional to their radial distance from the center.
Transformation
theta' = theta + strength * r
x' = r * cos(theta')
y' = r * sin(theta')
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the twirl effect. |
0.5
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the twirl distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |
Wave ¶
Bases: WarpTransform
Applies a wave distortion effect along the specified axis.
Transformation
y' = y + strength * amplitude * sin(2 * pi * frequency * x + phase) (if axis = 'horizontal')
x' = x + strength * amplitude * sin(2 * pi * frequency * y + phase) (if axis = 'vertical')
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
strength |
float
|
The strength of the distortion as defined by the scaling of the amplitude. |
1
|
amplitude |
float
|
The amplitude of the wave. |
0.1
|
frequency |
float
|
The frequency of the wave. |
1.0
|
phase |
float
|
The phase shift of the wave. |
0.0
|
axis |
str
|
The axis along which to apply the wave effect ('horizontal' or 'vertical'). |
'horizontal'
|
generate_warp_field ¶
generate_warp_field(height, width)
Generates the warp field for the wave distortion.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
height |
int
|
The height of the image. |
required |
width |
int
|
The width of the image. |
required |
Returns:
| Type | Description |
|---|---|
Tensor
|
The grid for warping the image. |