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’.

sigLookupTableChanged

Emits the HistogramLUTItem itself when the gradient changes

Type:

QtCore.Signal

sigLevelsChanged

Emits the HistogramLUTItem itself while the movable region is changing

Type:

QtCore.Signal

sigLevelChangeFinished

Emits the HistogramLUTItem itself when the movable region is finished changing

Type:

QtCore.Signal

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:
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.

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GradientEditorItem

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GradientLegend