Greetings fellow Gimp Users,
I make images using Gimp, but I assume that this question is not really
I have tens of thousands of images (postage stamps) on my site. Every
now and then when I am looking at a page I discover that the image (a
JPEG) has had is colors "sort of inverted". The JPEGs were created in
large batches by a script from UNcompressed TIFF images. When I go back
and look at the the original TIFF, I discover that its colors are "sort
of inverted" -- thus the JPEG is a correct rendition of the appearance
of its TIFF source.
Thus the problem is in the TIFF. But, the problem happens now and then,
over the course of years. The TIFFs are _not_ being intentionally
manipulated in that time. The images was originally okay, now its not.
It seems to be completely random, just one image here and there.
Somehow the TIFF is getting corrupted. I am assuming by a memory error
or a disk/RAID controller error, or such. The images are still openable
This is only happening to one out perhaps one out of five thousand
images, every five years. (I am just *guessing* at the error rate
because I only find out about them by randomly coming across them.)
But, if I have 40,000 images, that is eight images destroyed every five
years. (And often I am not able to replace the image because I no
longer have the item.)
This example image was originally created in 2006. I suspect (mostly
guessing) that it was corrupted sometime since 2010. There is no reason
that it would have been edited since that time and file modification
information shows nothing since 2006.
On Ubuntu Linux, using "identify -verbose filename.tif" I can read the
header information. The only odd thing (to my eye) is that the create
date is 2011 and the modification date is 2006:
I am guessing that means the corruption may have happened in 2011, even
though the filesystems own file datestamp is 2006 and the lsattr command
shows nothing unusual.
Here is example of a) the resulting JPEG (just to illustrate the nature
of the corruption); b) a similar JPEG to show generally what it is
supposed to look like; c) the corrupted TIFF.
Correct image of a similar, but different item:
This is the TIFF file (corrupted, but viewable in Gimp; colors are
sort-of-inverted) Size 496 KB:
My primary question is whether there is a "particular bit that is
getting flipped" that could be "unflipped" by some sort of non-visual
editing of the source TIFF file?
My secondary question is whether or not other people have seen this type
of problem crop up in large image libraries and what the causes have been?
Any thoughts appreciated.
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