A post that is the same or inferior to an already existing post.
Duplicates should not be confused for the following:
- image sample, an image typically used by sites to load images faster.
- md5 mismatch, an post that has a different md5 from the file at the source.
- revision, a post that has been revised by the artist from a previous version.
- scan, a post that has been scanned from another source.
A few cases where the tag applies:
- Images with identical pixel data, but different metadata.
- Lower resolution versions of the same post.
- Resized posts. Note that duplicate resized posts should not be tagged with md5 mismatch.
- Images of generally lower quality; often a result of jpeg artifacts.
Before you upload something, check if it has already been uploaded by using the IQDB image search or the "Find similar" button.
Most duplicates are tagged manually; only pixel-perfect duplicates are tagged automatically. There is no automated system in place to accurately tag non pixel-perfect duplicates given how easy it is to confuse them for the above (with the exception image samples where the original is already uploaded).
- Do not flag a duplicate post for deletion if your only reason is that the post is a duplicate.
- Don't add the duplicate tag on posts with visual differences (revisions, textless versions etc.).
- Avoid uploading visually identical posts.
- Check for differences with DuplicateBooru if you are unable to confirm with your own eyes.
Not to be confused with multiple sources, although they may overlap sometimes.
- multiple sources is about outside sources -- it means that multiple copies are available outside Danbooru.
- duplicate is about Danbooru -- it means that we have multiple copies of the same image.
- How can I tell exactly what changed between two images?
- Diffchecker Online compare images
- ImageMagick Multitool with compare function
- XnView MP Image viewer. Support EXIF, IPTC, XMP metadata
- ExifTool Command-line application for work with metadata