colors: Colors and colormap

This module provides API to manage colors.

silx.gui.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

silx.gui.colors.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

silx.gui.colors.DEFAULT_COLORMAPS = ('gray', 'reversed gray', 'temperature', 'red', 'green', 'blue')

Tuple of supported colormap names.

silx.gui.colors.DEFAULT_MIN_LIN = 0

Default min value if in linear normalization

silx.gui.colors.DEFAULT_MAX_LIN = 1

Default max value if in linear normalization

silx.gui.colors.DEFAULT_MIN_LOG = 1

Default min value if in log normalization

silx.gui.colors.DEFAULT_MAX_LOG = 10

Default max value if in log normalization

class silx.gui.colors.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

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

silx.gui.colors.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

silx.gui.colors.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.