HistogramLUTItem#

class pyqtgraph.HistogramLUTItem(
image=None,
fillHistogram=True,
levelMode='mono',
gradientPosition='right',
orientation='vertical',
)[source]#

GraphicsWidget with controls for adjusting the display of an ImageItem.

Includes:

  • Image histogram

  • Movable region over the histogram to select black/white levels

  • Gradient editor to define color lookup table for single-channel images

Parameters:

  • image (pyqtgraph.ImageItem, optional) – If provided, control will be automatically linked to the image and changes to the control will be reflected in the image’s appearance. This may also be set via setImageItem().

  • fillHistogram (bool, optional) – By default, the histogram is rendered with a fill. Performance may be improved by disabling the fill. Additional control over the fill is provided by fillHistogram().

  • levelMode (str, optional) –

    ‘mono’ (default)

    One histogram with a LinearRegionItem is displayed to control the black/white levels of the image. This option may be used for color images, in which case the histogram and levels correspond to all channels of the image.

    ‘rgba’

    A histogram and level control pair is provided for each image channel. The alpha channel histogram and level control are only shown if the image contains an alpha channel.

  • gradientPosition (str, optional) – Position of the gradient editor relative to the histogram. Must be one of {‘right’, ‘left’, ‘top’, ‘bottom’}. ‘right’ and ‘left’ options should be used with a ‘vertical’ orientation; ‘top’ and ‘bottom’ options are for ‘horizontal’ orientation.

  • orientation (str, optional) – The orientation of the axis along which the histogram is displayed. Either ‘vertical’ (default) or ‘horizontal’.

Variables:

  • sigLookupTableChanged (QtCore.Signal) – Emits the HistogramLUTItem itself when the gradient changes

  • sigLevelsChanged (QtCore.Signal) – Emits the HistogramLUTItem itself while the movable region is changing

  • sigLevelChangeFinished (QtCore.Signal) – Emits the HistogramLUTItem itself when the movable region is finished changing

See also

ImageItem

HistogramLUTItem is most useful when paired with an ImageItem.

ImageView

Widget containing a paired ImageItem and HistogramLUTItem.

HistogramLUTWidget

QWidget containing a HistogramLUTItem for widget-based layouts.

__init__(
image=None,
fillHistogram=True,
levelMode='mono',
gradientPosition='right',
orientation='vertical',
)[source]#
autoHistogramRange()[source]#

Enable auto-scaling on the histogram plot.

disableAutoHistogramRange()[source]#

Disable auto-scaling on the histogram plot.

fillHistogram(
fill=True,
level=0.0,
color=(100, 100, 200),
)[source]#

Control fill of the histogram curve(s).

Parameters:

  • fill (bool, optional) – Set whether or not the histogram should be filled.

  • level (float, optional) – Set the fill level. See PlotCurveItem.setFillLevel. Only used if fill is True.

  • color (color_like, optional) – Color to use for the fill when the histogram levelMode == "mono". See PlotCurveItem.setBrush.

getHistogramRange()[source]#

Returns range on the histogram plot.

getLevels()[source]#

Return the min and max levels.

For rgba mode, this returns a list of the levels for each channel.

getLookupTable(
img=None,
n=None,
alpha=None,
)[source]#

Return a lookup table from the color gradient defined by this HistogramLUTItem.

setHistogramRange(
mn,
mx,
padding=0.1,
)[source]#

Set the X/Y range on the histogram plot, depending on the orientation. This disables auto-scaling.

setImageItem(
img,
)[source]#

Set an ImageItem to have its levels and LUT automatically controlled by this HistogramLUTItem.

setLevelMode(
mode,
)[source]#

Set the method of controlling the image levels offered to the user.

Options are ‘mono’ or ‘rgba’.

setLevels(
min=None,
max=None,
rgba=None,
)[source]#

Set the min/max (bright and dark) levels.

Parameters:

  • min (float, optional) – Minimum level.

  • max (float, optional) – Maximum level.

  • rgba (list, optional) – Sequence of (min, max) pairs for each channel for ‘rgba’ mode.