colors: Colors and colormap

This module provides API to manage colors.

rgba(color, colorDict=None)

Convert color code ‘#RRGGBB’ and ‘#RRGGBBAA’ to (R, G, B, A)

It also convert RGB(A) values from uint8 to float in [0, 1] and accept a QColor as color argument.

Parameters:

• color (str) – The color to convert
• colorDict (dict) – A dictionary of color name conversion to color code

Returns:

RGBA colors as floats in [0., 1.]

Return type:

tuple

cursorColorForColormap(colormapName)

Get a color suitable for overlay over a colormap.

Parameters:colormapName (str) – The name of the colormap. Returns:Name of the color. Return type:str

DEFAULT_COLORMAPS = ('gray', 'reversed gray', 'temperature', 'red', 'green', 'blue')

Tuple of supported colormap names.

DEFAULT_MIN_LIN = 0

Default min value if in linear normalization

DEFAULT_MAX_LIN = 1

Default max value if in linear normalization

DEFAULT_MIN_LOG = 1

Default min value if in log normalization

DEFAULT_MAX_LOG = 10

Default max value if in log normalization

class Colormap(name='gray', colors=None, normalization='linear', vmin=None, vmax=None)

Description of a colormap

Parameters:

• name (str) – Name of the colormap
• colors (tuple) – optional, custom colormap. Nx3 or Nx4 numpy array of RGB(A) colors, either uint8 or float in [0, 1]. If ‘name’ is None, then this array is used as the colormap.
• normalization (str) – Normalization: ‘linear’ (default) or ‘log’
• vmin (float) – Lower bound of the colormap or None for autoscale (default)
• vmax (float) – Upper bounds of the colormap or None for autoscale (default)

LINEAR = 'linear'

constant for linear normalization

LOGARITHM = 'log'

constant for logarithmic normalization

NORMALIZATIONS = ('linear', 'log')

Tuple of managed normalizations

sigChanged = <PySide2.QtCore.Signal object>

Signal emitted when the colormap has changed.

isAutoscale()

Return True if both min and max are in autoscale mode

getName()

Return the name of the colormap :rtype: str

getNColors(nbColors=None)

Returns N colors computed by sampling the colormap regularly.

Parameters:nbColors (int or None) – The number of colors in the returned array or None for the default value. The default value is 256 for colormap with a name (see setName()) and it is the size of the LUT for colormap defined with setColormapLUT(). Returns:2D array of uint8 of shape (nbColors, 4) Return type:numpy.ndarray

setName(name)

Set the name of the colormap to use.

Parameters:name (str) – The name of the colormap. At least the following names are supported: ‘gray’, ‘reversed gray’, ‘temperature’, ‘red’, ‘green’, ‘blue’, ‘jet’, ‘viridis’, ‘magma’, ‘inferno’, ‘plasma’.

getColormapLUT()

Return the list of colors for the colormap or None if not set

Returns:the list of colors for the colormap or None if not set Return type:numpy.ndarray or None

setColormapLUT(colors)

Set the colors of the colormap.

Parameters:colors (numpy.ndarray) – the colors of the LUT. If float, it is converted from [0, 1] to uint8 range. Otherwise it is casted to uint8.

getNormalization()

Return the normalization of the colormap (‘log’ or ‘linear’)

Returns:the normalization of the colormap Return type:str

setNormalization(norm)

Set the norm (‘log’, ‘linear’)

Parameters:norm (str) – the norm to set

getVMin()

Return the lower bound of the colormap

Returns:the lower bound of the colormap Return type:float or None

setVMin(vmin)

Set the minimal value of the colormap

Parameters:vmin (float) – Lower bound of the colormap or None for autoscale (default) value)

getVMax()

Return the upper bounds of the colormap or None

Returns:the upper bounds of the colormap or None Return type:float or None

setVMax(vmax)

Set the maximal value of the colormap

Parameters:vmax (float) – Upper bounds of the colormap or None for autoscale (default)

isEditable()

Return if the colormap is editable or not

Returns:editable state of the colormap :rtype: bool

setEditable(editable)

Set the editable state of the colormap

Parameters:editable (bool) – is the colormap editable

getColormapRange(data=None)

Return (vmin, vmax)

Returns:the tuple vmin, vmax fitting vmin, vmax, normalization and data if any given Return type:tuple

setVRange(vmin, vmax)

Set the bounds of the colormap

Parameters:

• vmin – Lower bound of the colormap or None for autoscale (default)
• vmax – Upper bounds of the colormap or None for autoscale (default)

copy()

Return a copy of the Colormap.

Return type:silx.gui.colors.Colormap

applyToData(data)

Apply the colormap to the data

Parameters:data (numpy.ndarray) – The data to convert.

static getSupportedColormaps()

Get the supported colormap names as a tuple of str.

The list should at least contain and start by: (‘gray’, ‘reversed gray’, ‘temperature’, ‘red’, ‘green’, ‘blue’) :rtype: tuple

restoreState(byteArray)

Read the colormap state from a QByteArray.

Parameters:byteArray (qt.QByteArray) – Stream containing the state Returns:True if the restoration sussseed Return type:bool

saveState()

Save state of the colomap into a QDataStream.

Return type:qt.QByteArray

preferredColormaps()

Returns the name of the preferred colormaps.

This list is used by widgets allowing to change the colormap like the ColormapDialog as a subset of colormap choices.

Return type:tuple of str

setPreferredColormaps(colormaps)

Set the list of preferred colormap names.

Warning: If a colormap name is not available it will be removed from the list.

Parameters:colormaps (iterable of str) – Not empty list of colormap names Raises:ValueError – if the list of available preferred colormaps is empty.