.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "auto_examples/general_examples/plot_04_empr_3d.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_auto_examples_general_examples_plot_04_empr_3d.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_auto_examples_general_examples_plot_04_empr_3d.py:


EMPR on an 3D Tensor
====================

Load an RGB image as a 3D tensor, run EMPR, reconstruct the tensor, and compare
the reconstruction with the original image.

.. GENERATED FROM PYTHON SOURCE LINES 8-82



.. image-sg:: /auto_examples/general_examples/images/sphx_glr_plot_04_empr_3d_001.png
   :alt: Original image, EMPR reconstruction (order=3), Mean absolute error
   :srcset: /auto_examples/general_examples/images/sphx_glr_plot_04_empr_3d_001.png
   :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    Image path: /home/runner/work/HDMRLib/HDMRLib/docs/_static/examples/squirell.png
    Input shape: (160, 160, 3)
    Reconstructed shape: (160, 160, 3)
    Available component keys: ['g_0', 'g_1', 'g_2', 'g_3', 'g_1,2', 'g_1,3', 'g_2,3', 'g_1,2,3']
    Mean absolute error: 3.2556784236118884e-18

    (np.float64(-0.5), np.float64(159.5), np.float64(159.5), np.float64(-0.5))





|

.. code-block:: Python


    from pathlib import Path

    import matplotlib.pyplot as plt
    import numpy as np
    import os
    from PIL import Image

    from hdmrlib import EMPR


    candidates = [
        Path(os.environ.get("GITHUB_WORKSPACE", "")) / "docs" / "_static" / "examples" / "squirell.png",
        Path("docs/_static/examples/squirell.png"),
        Path("_static/examples/squirell.png"),
    ]

    image_path = None
    for candidate in candidates:
        if str(candidate) and candidate.exists():
            image_path = candidate
            break

    if image_path is None:
        raise FileNotFoundError(
            "Could not find squirell.png. Checked:\n"
            + "\n".join(str(p) for p in candidates)
        )

    # Load image 
    img = Image.open(image_path).convert("RGB")
    max_size = 160
    img.thumbnail((max_size, max_size), Image.Resampling.LANCZOS)

    X = np.asarray(img, dtype=np.float64) / 255.0

    # RGB image is a 3D tensor, so use order=3
    empr = EMPR(X, order=3)
    X_reconstructed = np.asarray(empr.reconstruct(), dtype=np.float64)
    components = empr.components()

    # Clip for display
    X_display = np.clip(X, 0.0, 1.0)
    X_reconstructed_display = np.clip(X_reconstructed, 0.0, 1.0)

    # Mean absolute error across RGB channels
    error_map = np.mean(np.abs(X_display - X_reconstructed_display), axis=2)

    print("Image path:", image_path)
    print("Input shape:", X.shape)
    print("Reconstructed shape:", X_reconstructed.shape)
    print("Available component keys:", list(components.keys()))
    print("Mean absolute error:", float(np.mean(error_map)))

    # Create three equal-sized image axes + one separate colorbar axis.
    fig = plt.figure(figsize=(13, 4.2), constrained_layout=True)
    gs = fig.add_gridspec(1, 4, width_ratios=[1, 1, 1, 0.05])

    ax0 = fig.add_subplot(gs[0, 0])
    ax1 = fig.add_subplot(gs[0, 1])
    ax2 = fig.add_subplot(gs[0, 2])
    cax = fig.add_subplot(gs[0, 3])

    # Use nearest to avoid display blur in docs/screenshots.
    ax0.imshow(X_display, interpolation="nearest")
    ax0.set_title("Original image")
    ax0.axis("off")

    ax1.imshow(X_reconstructed_display, interpolation="nearest")
    ax1.set_title("EMPR reconstruction (order=3)")
    ax1.axis("off")

    im = ax2.imshow(error_map, cmap="viridis", interpolation="nearest")
    ax2.set_title("Mean absolute error")
    ax2.axis("off")

.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.446 seconds)


.. _sphx_glr_download_auto_examples_general_examples_plot_04_empr_3d.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: plot_04_empr_3d.ipynb <plot_04_empr_3d.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: plot_04_empr_3d.py <plot_04_empr_3d.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: plot_04_empr_3d.zip <plot_04_empr_3d.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_