Interactive image cutting and thresholding
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**A simple demo of a quib-based GUI.**

-  **Features**

   -  Graphics quibs
   -  Graphics-driven assignments
   -  Inverse assignments
   -  Matplotlib widgets with quibs

-  **Try me**

   -  Try dragging/resizing the Region of Interest (ROI) in the main
      image.
   -  Try dragging/resizing the rectangle around the cut image in the
      second figure.
   -  Try moving the thresholds.

.. code:: python

    from pyquibbler import iquib, initialize_quibbler
    initialize_quibbler()

.. code:: python

    import matplotlib.pyplot as plt
    from matplotlib.widgets import RectangleSelector
    import numpy as np
    %matplotlib tk

.. code:: python

    # Load an image:
    filename = iquib('bacteria_in_droplets.tif')
    img_main = plt.imread(filename);

.. code:: python

    # Show the image:
    plt.figure()
    ax = plt.gca()
    ax.imshow(img_main);

.. code:: python

    # Define and plot a rectangle Region Of Interest (ROI)
    ROI = iquib(np.array([250, 400, 300, 450]))
    rectprops = dict(edgecolor='w', alpha=0.7, fill=False, linewidth=3)
    RectangleSelector(ax, extents=ROI, props=rectprops);

.. code:: python

    # Cut the ROI from the main image:
    img_cut = img_main[ROI[2]:ROI[3], ROI[0]:ROI[1], :]
    
    # Plot the cut image:
    fig2 = plt.figure()
    ax_cut = fig2.add_axes([0.05, 0.55, 0.35, 0.4])
    ax_cut.imshow(img_cut);

.. code:: python

    # Threshold each of the RGB channels:
    thresholds_rgb = iquib(np.array([160, 170, 150])) # <-- input: RGB thresholds
    img_cut01 = img_cut > np.reshape(thresholds_rgb,(1, 1, 3))
    
    # Plot the thresholded image:
    ax_cut01 = fig2.add_axes([0.05, 0.05, 0.35, 0.4])
    ax_cut01.imshow(img_cut01 * 1.);

.. code:: python

    # Calculate area above threshold for each color:
    fraction_above_threshold = np.average(img_cut01, (0, 1))
    
    # Plot detected areas:
    ax_area = fig2.add_axes([0.6, 0.4, 0.3, 0.55])
    rgb = ['Red', 'Green', 'Blue']
    ax_area.bar(rgb, fraction_above_threshold * 100, color=list('rgb'))
    ax_area.axis([-0.5, 2.5, 0, 1.5])
    ax_area.set_ylabel('Total detected area, %');

.. code:: python

    # Threshold controls
    ax_thr = fig2.add_axes([0.6, 0.05, 0.3, 0.2])
    ax_thr.axis([-0.5, 2.5, 0, 255])
    ax_thr.xaxis.grid(True)
    ax_thr.plot(rgb, thresholds_rgb, 'sk', markersize=16, markerfacecolor='k');

.. code:: python

    # Add a "draggable" rectangle ROI around the extracted image:
    shifted_ROI = ROI - ROI[[0, 0, 2, 2]]
    shrinked_shifted_ROI = shifted_ROI + [7, -7, +7, -7]
    RectangleSelector(ax_cut, extents=shrinked_shifted_ROI, props=rectprops);
.. image:: ../images/demo_gif/quibdemo_image_ROI.gif