[Image-SIG] General question on JPEG file format
Ken McDonald
ken@be.com
Sat, 1 Jul 2000 02:48:14 -0700
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This isn't really a Python or PIL question, but I thought
the people reading this particular list were likely to know
the answer :-)
My understanding is that JPEG is really just a compression
algorithm, and that what most people think of as JPEG files
are actually JFIF files. From perusing the specs for a JFIF
file, it also seems that JFIF makes provision for the inclusion
of thumbnails and other metadata about the main image. However,
I've never actually seen this used by picture viewers, creators,
etc. Since I just got a shiny new digital camera, I'm interested
in writing a program that would take images from the camera,
and insert, if possible, and thumbnail and other info (f-stop,
exposure, etc.) into the image file. Is this possible? Are there
reasons this isn't commonly done with JPEG/JFIF files?
Thanks,
Ken
ken@be.com
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<DIV><FONT face=3DArial size=3D2>This isn't really a Python or PIL =
question,=20
but I thought</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>the people reading this particular list =
were likely=20
to know</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>the answer :-)</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>My understanding is that JPEG is really =
just a=20
compression</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>algorithm, and that what most people =
think of as=20
JPEG files</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>are actually JFIF files. From perusing =
the specs=20
for a JFIF</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>file, it also seems that JFIF makes =
provision for=20
the inclusion</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>of thumbnails and other metadata about =
the main=20
image. However,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I've never actually seen this used by =
picture=20
viewers, creators,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>etc. Since I just got a shiny new =
digital camera,=20
I'm interested</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>in writing a program that would take =
images from=20
the camera,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>and insert, if possible, and thumbnail =
and other=20
info (f-stop,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>exposure, etc.) into the image file. Is =
this=20
possible? Are there</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>reasons this isn't commonly done with =
JPEG/JFIF=20
files?</FONT></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Ken</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>ken@be.com</FONT></DIV></BODY></HTML>
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