On 12/18/2009 05:48 PM, Sven Neumann wrote:
> Hi,
> On Fri, 2009-12-18 at 15:39 -0500, Jay Smith wrote:
>> By the way, if possible, I would like to do this parasite removal on
>> tens of thousands of files.  Perhaps as the 'exec' of a 'find' command.
> I don't understand why you are even considering to use GIMP then. If all
> you care about is the image data, then a simple tifftopnm | pnmtotiff
> will probably do the trick.
> Sven

Hi Sven,

I am afraid I am not 100% following what you are saying.  Perhaps I
miscommunicated.  Or perhaps I am just not filling in assumed knowledge
well enough.

I want to use Gimp as an image editor.

However, there are thousands of images that have been created over the
years on different versions of various programs, some of which have
varying ICC profiles embedded.  And, then, importantly, there are
apparently some that have corrupted ICC profiles which were caused by a
 major data corruption event years ago.

So, I was asking about how to get to sRGB for all them (i.e. remove the
color profile).  You had mentioned some methods, but I don't have enough
information on how to use those methods.

Perhaps I am really missing something -- in Gimp is there a method /
command to (one at a time) remove the color profile parasite?  That
question was never answered in the archived newsgroup messages I have
read.  Instead there is reference to changing it to sRGB which
apparently accomplishes the same thing as removing the color profile
parasite.  I thought that I had once done some method/command in Gimp to
remove the color profile parasite, but perhaps I am mis-remembering.

My goals are two-fold:

a) When I find an individual image with a corrupted profile, I wish to
remove the color profile parasite.  (Changing to sRGB is not an option
due to the previously discussed problem that it is a corrupted file and
of course the plug-in is not always going to be happy with it.)  I am no
farther along in understanding whether Gimp has a tool to do this.

b) I would like to find a method to remove color profile parasites on
thousands of images, via the command line.  You have suggested trying
"tifftopnm | pnmtotiff" do to this.  I will experiment with that, but I
have a concern as noted below.

Based on your most recent recommendation, I looked at
and I am not sure how this helps me, unless you are suggesting to
ROUNDTRIP using these two programs.

However, I noted it said [below] that theoretically you can lose
information in certain cases.  I have no idea if my images would be
affected by that.

"The PNM output has the same maxval as the Tiff input, except that if
the Tiff input is colormapped (which implies a maxval of 65535) the PNM
output has a maxval of 255. Though this may result in lost information,
such input images hardly ever actually have more color resolution than a
maxval of 255 provides and people often cannot deal with PNM files that
have maxval > 255. By contrast, a non-colormapped Tiff image that
doesn't need a maxval > 255 doesn't have a maxval > 255, so when
tifftopnm sees a non-colormapped maxval > 255, it takes it seriously and
produces a matching output maxval. Another exception is where the TIFF
maxval is greater than 65535, which is the maximum allowed by the Netpbm
formats. In that case, tifftopnm uses a maxval of 65535, and you lose
some information in the conversion."


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