.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "auto_examples/color_exposure/plot_adapt_rgb.py" .. LINE NUMBERS ARE GIVEN BELOW. .. only:: html .. note:: :class: sphx-glr-download-link-note :ref:`Go to the end ` to download the full example code or to run this example in your browser via Binder .. rst-class:: sphx-glr-example-title .. _sphx_glr_auto_examples_color_exposure_plot_adapt_rgb.py: ========================================= Adapting gray-scale filters to RGB images ========================================= There are many filters that are designed to work with gray-scale images but not with color images. To simplify the process of creating functions that can adapt to RGB images, scikit-image provides the ``adapt_rgb`` decorator. To actually use the ``adapt_rgb`` decorator, you have to decide how you want to adapt the RGB image for use with the gray-scale filter. There are two pre-defined handlers: ``each_channel`` Pass each of the RGB channels to the filter one-by-one, and stitch the results back into an RGB image. ``hsv_value`` Convert the RGB image to HSV and pass the value channel to the filter. The filtered result is inserted back into the HSV image and converted back to RGB. Below, we demonstrate the use of ``adapt_rgb`` on a couple of gray-scale filters: .. GENERATED FROM PYTHON SOURCE LINES 25-40 .. code-block:: Python from skimage.color.adapt_rgb import adapt_rgb, each_channel, hsv_value from skimage import filters @adapt_rgb(each_channel) def sobel_each(image): return filters.sobel(image) @adapt_rgb(hsv_value) def sobel_hsv(image): return filters.sobel(image) .. GENERATED FROM PYTHON SOURCE LINES 41-44 We can use these functions as we would normally use them, but now they work with both gray-scale and color images. Let's plot the results with a color image: .. GENERATED FROM PYTHON SOURCE LINES 44-63 .. code-block:: Python from skimage import data from skimage.exposure import rescale_intensity import matplotlib.pyplot as plt image = data.astronaut() fig, (ax_each, ax_hsv) = plt.subplots(ncols=2, figsize=(14, 7)) # We use 1 - sobel_each(image) but this won't work if image is not normalized ax_each.imshow(rescale_intensity(1 - sobel_each(image))) ax_each.set_xticks([]), ax_each.set_yticks([]) ax_each.set_title("Sobel filter computed\n on individual RGB channels") # We use 1 - sobel_hsv(image) but this won't work if image is not normalized ax_hsv.imshow(rescale_intensity(1 - sobel_hsv(image))) ax_hsv.set_xticks([]), ax_hsv.set_yticks([]) ax_hsv.set_title("Sobel filter computed\n on (V)alue converted image (HSV)") .. image-sg:: /auto_examples/color_exposure/images/sphx_glr_plot_adapt_rgb_001.png :alt: Sobel filter computed on individual RGB channels, Sobel filter computed on (V)alue converted image (HSV) :srcset: /auto_examples/color_exposure/images/sphx_glr_plot_adapt_rgb_001.png :class: sphx-glr-single-img .. rst-class:: sphx-glr-script-out .. code-block:: none Text(0.5, 1.0, 'Sobel filter computed\n on (V)alue converted image (HSV)') .. GENERATED FROM PYTHON SOURCE LINES 64-83 Notice that the result for the value-filtered image preserves the color of the original image, but channel filtered image combines in a more surprising way. In other common cases, smoothing for example, the channel filtered image will produce a better result than the value-filtered image. You can also create your own handler functions for ``adapt_rgb``. To do so, just create a function with the following signature:: def handler(image_filter, image, *args, **kwargs): # Manipulate RGB image here... image = image_filter(image, *args, **kwargs) # Manipulate filtered image here... return image Note that ``adapt_rgb`` handlers are written for filters where the image is the first argument. As a very simple example, we can just convert any RGB image to grayscale and then return the filtered result: .. GENERATED FROM PYTHON SOURCE LINES 83-92 .. code-block:: Python from skimage.color import rgb2gray def as_gray(image_filter, image, *args, **kwargs): gray_image = rgb2gray(image) return image_filter(gray_image, *args, **kwargs) .. GENERATED FROM PYTHON SOURCE LINES 93-98 It's important to create a signature that uses ``*args`` and ``**kwargs`` to pass arguments along to the filter so that the decorated function is allowed to have any number of positional and keyword arguments. Finally, we can use this handler with ``adapt_rgb`` just as before: .. GENERATED FROM PYTHON SOURCE LINES 98-114 .. code-block:: Python @adapt_rgb(as_gray) def sobel_gray(image): return filters.sobel(image) fig, ax = plt.subplots(ncols=1, nrows=1, figsize=(7, 7)) # We use 1 - sobel_gray(image) but this won't work if image is not normalized ax.imshow(rescale_intensity(1 - sobel_gray(image)), cmap=plt.cm.gray) ax.set_xticks([]), ax.set_yticks([]) ax.set_title("Sobel filter computed\n on the converted grayscale image") plt.show() .. image-sg:: /auto_examples/color_exposure/images/sphx_glr_plot_adapt_rgb_002.png :alt: Sobel filter computed on the converted grayscale image :srcset: /auto_examples/color_exposure/images/sphx_glr_plot_adapt_rgb_002.png :class: sphx-glr-single-img .. GENERATED FROM PYTHON SOURCE LINES 115-120 .. note:: A very simple check of the array shape is used for detecting RGB images, so ``adapt_rgb`` is not recommended for functions that support 3D volumes or color images in non-RGB spaces. .. rst-class:: sphx-glr-timing **Total running time of the script:** (0 minutes 1.603 seconds) .. _sphx_glr_download_auto_examples_color_exposure_plot_adapt_rgb.py: .. only:: html .. container:: sphx-glr-footer sphx-glr-footer-example .. container:: binder-badge .. image:: images/binder_badge_logo.svg :target: https://mybinder.org/v2/gh/scikit-image/scikit-image/v0.23.2?filepath=notebooks/auto_examples/color_exposure/plot_adapt_rgb.ipynb :alt: Launch binder :width: 150 px .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: plot_adapt_rgb.ipynb ` .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: plot_adapt_rgb.py ` .. only:: html .. rst-class:: sphx-glr-signature `Gallery generated by Sphinx-Gallery `_