Universal viewer (UV) fails rendering png with transparent alpha channel #3760
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This issue has been automatically marked as stale because it has not had activity for 30 days. It will be closed if no further activity occurs within 14 days. Thank you for your contributions. |
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I wonder if it will become a problem having this property called "channels" when audio files have "channels" as well. |
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@cjcolvar good point, I'll rename it alphachannels ... I want to get this finished this week if at all possible |
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It would be good for someone else to review this because I don't work with images and don't feel confident enough. |
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@cjcolvar thanks! I need to get the tests passing, and do a bit of manual QA of my own, then I'll ping a couple of reviewers |
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… also bumps the circle ci cache_key version to rebuild the test app
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@no-reply Hi Tom, any chance of a review? |
| @@ -33,7 +33,7 @@ def mount_route | |||
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| def override_image_url_builder_in_hyrax_config | |||
| insert_into_file 'config/initializers/hyrax.rb', before: /^ # config.iiif_image_url_builder/ do | |||
| " config.iiif_image_url_builder = lambda do |file_id, base_url, size|\n" \ | |||
| " config.iiif_image_url_builder = lambda do |file_id, base_url, size, format|\n" \ | |||
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Does this change in the lambda signature require updating documentation or at least need to be called out in the 3.0 migration docs?
Fixes #3422; required a new version of Riiif: #125 released as 2.1.
This PR, combined with a change in Riiif will fix an issue whereby images with an alpha channel are incorrectly rendered by Universal Viewer backed by Riiif.
The incorrect rendering occurs because Riiif is asked for a 'jpg', and jpegs do not support alpha channels.
One complication is that Universal Viewer requests 'jpg' even if png is specified in the manifest. The changes proposed in Riiif help to get around that by returning a png if an alpha channel present, irrespective of the request format.
Changes in Hyrax are:
Extend the characterize job to run Imagemagick identify and extract channel information (via the Riiif::ImageInfoExtractor) ... we need channel information to pass to Riiif, and we cannot get this from FITS AFAIK. Channel information could also be useful for preservation purposes, so it is useful to collect it. This channel information is added to the characterization_proxy and indexed into solr.
Change the Riiif info_service to return format AND alpha_channels; Riiif will then check for an alpha channel and preserve this, returning a png instead of a jpg.
@samvera/hyrax-code-reviewers