commons-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Charles Matthew Chen <>
Subject Re: [Sanselan] - Help Parsing EXIF Info embedded in PNG
Date Thu, 04 Mar 2010 02:35:38 GMT
   First, calling getText() on Sanselan's zTXt chunk returns the
uncompressed contents:

   Next, I'm not sure exactly what is meant by "raw" Exif data, but
Exif is a binary format.  It'd be strange to store it in a zTXt chunk.

   Phil's exiftool documentation is in many ways the defacto standard
for image metadata practices, especially for these non-standardized
dark corners.  In the absence of a standard, I'm not sure what you're
looking for or asking to be implemented.

   What is the source of the images with this data?  What software is
writing these PNGs?


On Wed, Mar 3, 2010 at 3:22 PM, Stephen Nesbitt
<> wrote:
> Hi Chris:
> I honestly don't think so. First of all if I use exiftool on one of my PNG I
> do get a dump of EXIF info. And this corresponds to the documentation for
> exiftool (
> which indicates that embedding EXIF is indeed not a PNG standard *but*
> embedding arbitrary tag names is allowable and that one of the arbitrary but
> standard tag names is "Raw profile type exif" and that it contains "raw" EXIF
> info.
> So I think the key questions is how do I parse the data and in particular is
> the data returned by the zTxt.getText() method is compressed or uncompressed.
> -steve
> On Wednesday 03 March 2010 11:25:12 am Christopher Schultz wrote:
>> Stephen,
>> On 3/3/2010 1:38 PM, Stephen Nesbitt wrote:
>> > I am trying to figure out how to parse EXIF info embedded in a PNG.
>> I'm no PNG/EXIF expert, but Wikipedia's EXIF page says that PNG doesn't
>> support EXIF:
>> "
>> The specification uses the existing JPEG, TIFF Rev. 6.0, and RIFF WAV
>> file formats, with the addition of specific metadata tags. It is not
>> supported in JPEG 2000, PNG, or GIF.
>> "
>> (
>> Maybe that's the problem?
>> -chris
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail:
>> For additional commands, e-mail:
> ---------------------------------------------------------------------
> To unsubscribe, e-mail:
> For additional commands, e-mail:

To unsubscribe, e-mail:
For additional commands, e-mail:

View raw message