Getting the average color of an image in Sanity CMS using metadata palette info.

  "image": image {
    ...,
    "metadata": asset->metadata
  }

Image assets also contain useful metadata such as Low Quality Image Previews (LQIP), palette information and original image dimension as well as aspect ratio.

{
            name: 'coverImage',
            title: 'Cover Image',
            type: 'image',
            fieldset: 'settings',
            validation: (Rule) => Rule.required(),
        },

*[_type == "post"] | order(title) {
  'key': _id,
  'type': _type,
  title,
  'slug': slug.current,
  'image': coverImage.asset->url,
}

'image': coverImage {
  'url': asset->url,
  'metadata': asset->metadata
}

'image': coverImage.asset->{
  url,
  metadata
}