GitHub PushEvent at 2014-02-06 01:38:18
Repository: oiio
Actor: lgritz
Payload: {"shas":[["22c41ec646335afa354d468292224c4889b47bdf","f0a1ce6f80112d72f7276457fd261d671b827567@larrygritz.com","IC/TS: Don't honor SHA-1 fingerprint for files not written by OIIO.\n\nEvil edge case: user creates MIP-mapped texture with maketx (which\nwrites the hash into either \"oiio:SHA-1\" metadata, or for formats that\ndon't support arbitrary metadata, into the \"ImageDescription\"), then\nuser alters the image with software like PhotoShop and somehow\nre-outputs a MIP-map and figures they don't need to re-maketx it.  Yet\nit still contains the metadata with the SHA-1 of the original image, and\nso will be recognized by the ImageCache/TextureSystem as an exact\nduplicate of the original. Oops.\n\nThis patch adds a heuristic wherein if the \"Software\" metadata does\nnot start with \"OpenImageIO\" (which it will, if written by maketx),\nthe SHA-1 fingerprint will be forgotten.  (In particular, we believe\nthat PhotoShop will rewrite the \"Software\" metadata.)  We are also\ncareful for ImageBufAlgo functions and in oiiotool itself to erase\nany fingerprints that are found in the input, before altering images.\n\nThis is not perfect -- it can still incorrectly classify an image as a\nduplicate if it was altered by a program that does not overwrite the\n\"Software\" metadata, yet alters the pixels.  So don't do that, dummy!","Larry Gritz",false],["544ff3640d0d637b714cc58ef13177dfd4b74ae3","f0a1ce6f80112d72f7276457fd261d671b827567@larrygritz.com","Remove --hash description, no longer used by maketx","Larry Gritz",false]],"size":2,"ref":"refs/heads/master","head":"544ff3640d0d637b714cc58ef13177dfd4b74ae3"}