Density and jpeg photo shop metadata

[ponroy jonathan]

Hi all,

i try to use the lib jpeg turbo to read some meta data from the attached file but i have discovered that i can't get x_density and y_density because it is a jpeg produced with Adobe Photoshop.

Contrary to other jpeg files produced by other softwares, when examining the source code where we finished to call function "examine_app0" and get density parameters, with attached file, we call "examine_app14" and don't get the density parameters.

This is valid picture which can be opened with Gimp for example and see the density inside meta data.

Is there a way to get density parameters from this attached file with lib jpeg turbo?

Yhank you for your help

[DRC]

It appears that Adobe is storing the density information in EXIF tags,
and libjpeg-turbo doesn't inherently support EXIF tags (other than token
support in jpegtran for copying the entire EXIF block from one image to
another or modifying the width/height tags in a transformed image.)

I am not opposed to modifying libjpeg-turbo so that it can parse density
information (or other information, for that matter) from EXIF tags if
the image doesn't have a JFIF marker.  If someone wants to submit a PR
for that, I will review it.

[ponroy jonathan]

Thank you for your answer.

Do you think library Exiv2 (https://exiv2.org) is a good candidate to handle EXIF tags? What is your opinion?

[DRC]

Yes. For licensing reasons, libjpeg-turbo cannot use Exiv2, but that appears to be what GIMP uses.

On Dec 15, 2022, at 1:45 AM, ponroy jonathan <ponr...@gmail.com> wrote:



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