Add a page for cover art processing

config/options_cover.rst

@@ -19,7 +19,8 @@
       :doc:`options_location` /
       :doc:`options_cover_art_providers` /
       :doc:`options_cover_art_archive` /
-      :doc:`options_local_files`
+      :doc:`options_local_files` /
+      :doc:`options_cover_art_processing`
 
 .. toctree::
    :hidden:
@@ -28,3 +29,4 @@
    options_cover_art_providers
    options_cover_art_archive
    options_local_files
+   options_cover_art_processing

config/options_cover_art_processing.rst

@@ -0,0 +1,40 @@
+.. MusicBrainz Picard Documentation Project
+
+:index:`Cover Art Processing <pair: configuration; cover art>`
+===============================================================
+
+.. image:: images/options-cover-processing.png
+   :width: 100 %
+
+Picard can filter and process the images downloaded from the providers.  Image processing can differentiate between images
+embedded into tags and images saved as a separate file.  More filters and processors can be added by `plugins
+<https://picard.musicbrainz.org/plugins/>`_.
+
+**Discard images if below the given size**
+
+   This filter will discard any image with its width or its height lower than the given values.  With some providers,
+   like the Cover Art Archive, the image is discarded before it is downloaded.
+
+**Resize images to the given size**
+
+   Images can be scaled to the given dimensions.  You can also choose whether to allow images to increase in size, though
+   at a loss of image quality.  There are a few options as to how images are resized:
+
+   * **Maintain aspect ratio**: Scale the source image so that it fits within the target dimensions.  One of the final
+     image dimensions may be less than the target dimension if the source image and target dimensions have different aspect
+     ratios.
+
+   * **Scale to width**: Scale the width of the source image to the target width while keeping aspect ratio.
+
+   * **Scale to height**: Scale the height of the source image to the target height while keeping aspect ratio.
+
+   * **Crop to fit**: Scale the source image so that it completely fills the target dimensions in both directions.
+     If the source image and target dimensions have different aspect ratios, then there will be overflow in one direction which
+     will be (center) cropped.
+
+   * **Stretch to fit**: Stretch the image to exactly fit the specified dimensions, distorting it if necessary.
+
+**Convert images to the given format**
+
+   Images can be converted to the given format.  The available formats are JPEG, PNG, WebP, and TIFF.
+