c2e6202da6
The problem was that we were stripping color profiles from thumbnails, but we weren't setting `export_profile: "srgb"` to convert images to sRGB first. This resulted in wrong colors for images with non-sRGB color profiles, such as Adobe RGB. The fix is to convert images to sRGB when possible, while leaving CMYK and greyscale images alone. We leave CMYK images alone because we can't convert CMYK to sRGB without losing color. We leave greyscale images alone if they don't have a color profile, that way they stay as one-channel greyscale (or two-channel greyscale, in case of alpha) instead of being converted to three-channel sRGB. However, if a greyscale image has a color profile, then we have to convert to sRGB, otherwise the colors would be wrong when we strip the profile. We also have to set the import profile, otherwise images with broken embedded color profiles won't have a fallback profile and may get incorrect colors. In this case we also have to be careful, because we can't specify an sRGB fallback for greyscale or CMYK images.
122 lines
3.3 KiB
Ruby
122 lines
3.3 KiB
Ruby
# A MediaFile for a JPEG, PNG, or GIF file. Uses libvips for resizing images.
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#
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# @see https://github.com/libvips/ruby-vips
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# @see https://libvips.github.io/libvips/API/current
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class MediaFile::Image < MediaFile
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# http://jcupitt.github.io/libvips/API/current/VipsForeignSave.html#vips-jpegsave
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JPEG_OPTIONS = { Q: 90, background: 255, strip: true, interlace: true, optimize_coding: true }
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def dimensions
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image.size
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rescue Vips::Error
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[0, 0]
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end
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def is_corrupt?
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image.stats
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false
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rescue Vips::Error
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true
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end
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def duration
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return nil if !is_animated?
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video.duration
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end
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def frame_count
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if file_ext == :gif
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image.get("n-pages")
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elsif file_ext == :png
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metadata.fetch("PNG:AnimationFrames", 1)
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else
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nil
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end
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end
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def frame_rate
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return nil if !is_animated? || frame_count.nil? || duration.nil? || duration == 0
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frame_count / duration
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end
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def channels
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image.bands
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end
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def colorspace
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image.interpretation
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end
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def resize(max_width, max_height, format: :jpeg, **options)
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# @see https://www.libvips.org/API/current/Using-vipsthumbnail.md.html
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# @see https://www.libvips.org/API/current/libvips-resample.html#vips-thumbnail
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if colorspace == :srgb
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resized_image = preview_frame.image.thumbnail_image(max_width, height: max_height, import_profile: "srgb", export_profile: "srgb", **options)
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elsif colorspace == :cmyk
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# Leave CMYK as CMYK for better color accuracy than sRGB.
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resized_image = preview_frame.image.thumbnail_image(max_width, height: max_height, import_profile: "cmyk", export_profile: "cmyk", intent: :relative, **options)
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elsif colorspace == :"b-w" && has_embedded_profile?
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# Convert greyscale to sRGB so that the color profile is properly applied before we strip it.
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resized_image = preview_frame.image.thumbnail_image(max_width, height: max_height, export_profile: "srgb", **options)
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elsif colorspace == :"b-w"
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# Otherwise, leave greyscale without a profile as greyscale because
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# converting it to sRGB would change it from 1 channel to 3 channels.
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resized_image = preview_frame.image.thumbnail_image(max_width, height: max_height, **options)
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else
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raise NotImplementedError
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end
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output_file = Tempfile.new(["image-preview", ".jpg"])
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resized_image.jpegsave(output_file.path, **JPEG_OPTIONS)
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MediaFile::Image.new(output_file)
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end
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def preview(max_width, max_height)
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resize(max_width, max_height, size: :down)
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end
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def crop(max_width, max_height)
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resize(max_width, max_height, crop: :attention)
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end
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def preview_frame
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if is_animated?
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FFmpeg.new(file).smart_video_preview
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else
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self
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end
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end
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def is_animated?
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frame_count.to_i > 1
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end
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def is_animated_gif?
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file_ext == :gif && is_animated?
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end
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def is_animated_png?
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file_ext == :png && is_animated?
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end
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# Return true if the image has an embedded ICC color profile.
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def has_embedded_profile?
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image.icc_import(embedded: true)
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true
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rescue Vips::Error
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false
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end
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# @return [Vips::Image] the Vips image object for the file
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def image
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Vips::Image.new_from_file(file.path, fail: true).autorot
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end
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def video
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FFmpeg.new(file)
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end
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memoize :image, :video, :dimensions, :is_corrupt?, :is_animated_gif?, :is_animated_png?
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end
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