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I have two gifs: aura.gif which is a 7 frames animation, and character.gif which is a 1 frame image. When I overlay one on top of the other as shown below, I get a 7 frames animated image but the character in character.gif only appears in the first frame.
How can I make character.gif "appear" in all frames of aura.gif when I overlay both images?
This is the code I'm currently using:
require 'vips' character = File.open("character.gif").read character_b = Vips::Image.new_from_buffer(character, "", access: 'sequential', n: -1) aura = File.open("aura.gif").read aura_b = Vips::Image.new_from_buffer(aura, "", access: 'sequential', n: -1) aura_b.composite(character_b, "over", x: 0, y: 0).webpsave("composite.gif")
Thanks
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Hi @slnc,
That'll work, but it'll be pretty slow since every pixel will need to pass through a stack of n_pages composite operations. A quicker solution would be to copy the character n_pages times vertically, then do a single composite for the whole animation.
replicate tiles images:
https://www.rubydoc.info/gems/ruby-vips/Vips/Image#replicate-instance_method
It's extremely quick (it just copies pointers), so you can use it instead of any kind of loop over the X and Y dimensions.
Something like:
require 'vips' character = Vips::Image.new_from_file(ARGV[0]) aura = Vips::Image.new_from_file(ARGV[1], access: 'sequential') character = character .replicate(1, aura.get("n-pages")) aura
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After digging around a bit more I realized that Vips models animated images as a huge image so I ended up with this code which does what I need:
require 'vips' character = File.open("character.webp").read character_b = Vips::Image.new_from_buffer(character, "") aura = File.open("aura.webp").read aura_b = Vips::Image.new_from_buffer(aura, "", access: 'sequential', n: -1) page_h = aura_b.get("height") / aura_b.get("n-pages") aura_b.get("n-pages").times.each do |i| aura_b = aura_b.composite(character_b, "over", x: 0, y: page_h * i) end aura_b.webpsave("composite.webp")
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Hi @slnc,
That'll work, but it'll be pretty slow since every pixel will need to pass through a stack of n_pages composite operations. A quicker solution would be to copy the character n_pages times vertically, then do a single composite for the whole animation.
replicate tiles images:
https://www.rubydoc.info/gems/ruby-vips/Vips/Image#replicate-instance_method
It's extremely quick (it just copies pointers), so you can use it instead of any kind of loop over the X and Y dimensions.
Something like:
require 'vips' character = Vips::Image.new_from_file(ARGV[0]) aura = Vips::Image.new_from_file(ARGV[1], access: 'sequential') character = character .replicate(1, aura.get("n-pages")) aura .composite(character, "over") .write_to_file(ARGV[2])
Then:
$ ./x.rb ~/pics/character.gif ~/pics/aura.gif[n=-1] x.gif
To make:
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Thanks a lot John!
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Argh! Please don't cross post questions. It makes extra unnecessary work for volunteer maintainers.
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I'm sorry, I checked activity on both SO for tag "vips" and on this forum before posting. I posted on both places because I got the impression that neither had a lot of activity. I realize now that SO has quite a bit of activity and that my assumption that if I got an answer on both places it would be better because a question and a solution would appear on two places instead of one.
Perhaps consider making this request (to not cross-post) a bit more visible with maybe a "How to get help" section and a message like "If you need help go here or here but don't cross post" either on https://www.libvips.org/ or https://github.com/libvips/libvips? I easily spent 1h browsing those two sites but if that section exists, I missed it. Just a suggestion to help other people who might be tempted to do like I did. :-)
Again, thank you for your help John. 🙏
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It's a general rule with all active open source projects: ask once, and only ask around if you don't get a reply. libvips is an evenings and weekends thing, and it'd obviously be much more fun to work on adding something new than answering the same question several times.
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I understand, I will follow your directions next time.
Thanks again for your help, the code you helped me with is already in production. :-)
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