Colormap#

Render a single-channel image with a color map, e.g. to visualize depth, heat or edge maps.

Functions#

kornia.color.apply_colormap(input_tensor, colormap)[source]#

Apply to a gray torch.Tensor a colormap.

_images/apply_colormap.png
Parameters:

  • input_tensor (Tensor) – the input torch.Tensor of image.

  • colormap (ColorMap) – the colormap desired to be applied to the input torch.Tensor.

Return type:

Tensor

Returns:

A RGB torch.Tensor with the applied color map into the input_tensor.

Raises:

ValueError – If colormap is not a ColorMap object.

Note

The input torch.Tensor must be integer values in the range of [0-255] or float values in the range of [0-1].

Example

>>> input_tensor = torch.tensor([[[0, 1, 2], [15, 25, 33], [128, 158, 188]]])
>>> colormap = ColorMap(base=ColorMapType.autumn)
>>> apply_colormap(input_tensor, colormap)
tensor([[[[1.0000, 1.0000, 1.0000],
          [1.0000, 1.0000, 1.0000],
          [1.0000, 1.0000, 1.0000]],

         [[0.0000, 0.0159, 0.0159],
          [0.0635, 0.1111, 0.1429],
          [0.5079, 0.6190, 0.7302]],

         [[0.0000, 0.0000, 0.0000],
          [0.0000, 0.0000, 0.0000],
          [0.0000, 0.0000, 0.0000]]]])

Modules#

class kornia.color.ApplyColorMap(colormap)[source]#

Class for applying a colormap to images.

_images/ApplyColorMap.png
Parameters:

  • colormap (ColorMap) – Either the name of a built-in colormap or a ColorMap object.

  • num_colors – Number of colors in the colormap. Default is 256.

  • device – The device to put the generated colormap on.

  • dtype – The data type of the generated colormap.

Returns:

A RGB torch.Tensor with the applied color map into the input_tensor

Raises:

ValueError – If colormap is not a ColorMap object.

Note

The input torch.Tensor must be integer values in the range of [0-255] or float values in the range of [0-1].

Example

>>> input_tensor = torch.tensor([[[0, 1, 2], [15, 25, 33], [128, 158, 188]]])
>>> colormap = ColorMap(base=ColorMapType.autumn)
>>> ApplyColorMap(colormap=colormap)(input_tensor)
tensor([[[[1.0000, 1.0000, 1.0000],
          [1.0000, 1.0000, 1.0000],
          [1.0000, 1.0000, 1.0000]],

         [[0.0000, 0.0159, 0.0159],
          [0.0635, 0.1111, 0.1429],
          [0.5079, 0.6190, 0.7302]],

         [[0.0000, 0.0000, 0.0000],
          [0.0000, 0.0000, 0.0000],
          [0.0000, 0.0000, 0.0000]]]])
class kornia.color.ColorMap(base, num_colors=64, device=None, dtype=None)[source]#

Class to represent a colour map.

It can be created or selected from the built-in colour map. Please refer to the ColorMapType enum class to view all available colormaps.

Parameters:

  • base (Union[list[List[float]], str, ColorMapType]) – A list of RGB colors to define a new custom colormap or the name of a built-in colormap as str or

  • class. (using ColorMapType)

  • num_colors (int, optional) – Number of colors in the colormap. Default: 64

  • device (Optional[device], optional) – The device to put the generated colormap on. Default: None

  • dtype (Optional[dtype], optional) – The data type of the generated colormap. Default: None

Returns:

An object of the colormap with the num_colors length.

Examples

>>> ColorMap(base='viridis', num_colors=8).colors
tensor([[0.2813, 0.2621, 0.2013, 0.1505, 0.1210, 0.2463, 0.5259, 0.8557],
        [0.0842, 0.2422, 0.3836, 0.5044, 0.6258, 0.7389, 0.8334, 0.8886],
        [0.4072, 0.5207, 0.5543, 0.5574, 0.5334, 0.4519, 0.2880, 0.0989]])
Create a color map from the first color (RGB with range[0-1]) to the last one with num_colors length.
>>> ColorMap(base=[[0., 0.5 , 1.0], [1., 0.5, 0.]], num_colors=8).colors
tensor([[0.0000, 0.0000, 0.1250, 0.3750, 0.6250, 0.8750, 1.0000, 1.0000],
        [0.5000, 0.5000, 0.5000, 0.5000, 0.5000, 0.5000, 0.5000, 0.5000],
        [1.0000, 1.0000, 0.8750, 0.6250, 0.3750, 0.1250, 0.0000, 0.0000]])
kornia.color.RGBColor#

alias of List[float]

Color maps available:

class kornia.color.ColorMapType(value)[source]#

An enumeration for available colormaps.

List of available colormaps:

_images/ColorMapType.png
autumn = 1#
bone = 2#
jet = 3#
winter = 4#
rainbow = 5#
ocean = 6#
summer = 7#
spring = 8#
cool = 9#
hsv = 10#
brg = 11#
pink = 12#
hot = 13#
plasma = 14#
viridis = 15#
cividis = 16#
twilight = 17#
turbo = 18#
seismic = 19#
classmethod list()[source]#

Return a list of names of enumeration members.

Return type:

list[str]

Returns:

A list containing the names of enumeration members.