RGBA#

Tip

Learn more: https://en.wikipedia.org/wiki/RGBA_color_model

Functions#

kornia.color.rgb_to_rgba(image, alpha_val)[source]#

Convert an image from RGB to RGBA.

Parameters:

image (Tensor) – RGB Image to be converted to RGBA of shape \((*,3,H,W)\).
alpha_val (float, torch.Tensor) – A float number for the alpha value or a torch.tensor of shape \((*,1,H,W)\).

Return type:

Tensor

Returns:

RGBA version of the image with shape \((*,4,H,W)\).

Note

The current functionality is NOT supported by Torchscript.

Example

>>> input = torch.rand(2, 3, 4, 5)
>>> output = rgb_to_rgba(input, 1.) # 2x4x4x5

kornia.color.rgba_to_rgb(image, background_color=None)[source]#

Convert an image from RGBA to RGB using alpha compositing.

The function composites the input RGBA image over a background color. If no background color is provided, it defaults to a white background.

Parameters:

image (Tensor) – The RGBA image to be converted, with shape \((*,4,H,W)\).
background_color (Optional[Tensor], optional) – An optional background color. It can be a tuple or list of 3 floats, a torch.Tensor of shape \((*,3,H,W)\) for a per-pixel background, or a broadcastable torch.Tensor (e.g., \((*,3,1,1)\)). If None, a white background is used. Default: None

Return type:

Tensor

Returns:

The converted RGB image with shape \((*,3,H,W)\).

Example

>>> rgba_image = torch.rand(2, 4, 32, 32)
>>> # Test with default white background
>>> rgb_image_default = rgba_to_rgb(rgba_image) # 2x3x32x32
>>> # Test with a custom background color
>>> rgb_image_custom = rgba_to_rgb(rgba_image, background_color=(0.0, 0.0, 1.0)) # 2x3x32x32

kornia.color.rgba_to_bgr(image)[source]#

Convert an image from RGBA to BGR.

Parameters:: image (Tensor) – RGBA Image to be converted to BGR of shape \((*,4,H,W)\).
Return type:: Tensor
Returns:: RGB version of the image with shape \((*,3,H,W)\).

Example

>>> input = torch.rand(2, 4, 4, 5)
>>> output = rgba_to_bgr(input) # 2x3x4x5

Modules#

class kornia.color.RgbToRgba(alpha_val)[source]#

Convert an image from RGB to RGBA.

Add an alpha channel to existing RGB image.

Parameters:: alpha_val (Union[float, Tensor]) – A float number for the alpha value or a torch.Tensor of shape \((*,1,H,W)\).
Returns:: RGBA version of the image with shape \((*,4,H,W)\).
Return type:: torch.Tensor

Shape:

image: \((*, 3, H, W)\)
output: \((*, 4, H, W)\)

Note

The current functionality is NOT supported by Torchscript.

Example

>>> input = torch.rand(2, 3, 4, 5)
>>> rgba = RgbToRgba(1.)
>>> output = rgba(input)  # 2x4x4x5

class kornia.color.RgbaToRgb(*args, **kwargs)[source]#

Convert an image from RGBA to RGB.

Remove an alpha channel from RGB image.

Returns:: RGB version of the image.

Shape:

image: \((*, 4, H, W)\)
output: \((*, 3, H, W)\)

Example

>>> input = torch.rand(2, 4, 4, 5)
>>> rgba = RgbaToRgb()
>>> output = rgba(input)  # 2x3x4x5

class kornia.color.RgbaToBgr(*args, **kwargs)[source]#

Convert an image from RGBA to BGR.

Remove an alpha channel from BGR image.

Returns:: BGR version of the image.

Shape:

image: \((*, 4, H, W)\)
output: \((*, 3, H, W)\)

Example

>>> input = torch.rand(2, 4, 4, 5)
>>> rgba = RgbaToBgr()
>>> output = rgba(input)  # 2x3x4x5