PARTNER

Densho
Visit partner

PARENT OBJECT

Camp hospital area (ddr-densho-2-42)

FILE ID

ddr-densho-2-42-mezzanine-7a4bc7cdd9

SIZE

2.4 MB

TECHNICAL DETAILS

Original file found corrupted on June 17, 2024 by Micah Merryman. What follows are the steps take to correct the corruption on June 28, 2024 ran TiffUtil (built into MacOS in commandline) $TiffUtil -verboseinfo Sanity checked info returned by command – metadata meshes with what observed in photo Used an editor (MS Paint) that could load corrupted file to identify what pixel the corruption started on Using the rows per strip value (in the output of TiffUtil) Divide vertical pixel number by rows per strip to find the index of the corrupted strip (651 [pixel]/3 [strip value] = 217 – means it’s the 218 value/row in the strip offset dump given to us in the TiffUtil verboseinfo output) Once we identified which TIFF strip was the corrupted one, I wrote this one-off python script to go through every bit in that strip and output a copy of the file with that bit flipped. Because MaC OS was treating an error in decompressing that one strip as cause for blacking out the entire thumbnail, I then went through the 21,000+ thumbnails, scanning for any that weren't black and checking them. The script is not general-purpose and is hacked together to handle exactly this one file with the known values that we gathered through examining it with tiffutil but here it is for reference.

RIGHTS

Copyright restricted