It depends on the software you use to prepare these images for the
Web. Adobe Photoshop, through its Save for Web feature, will strip out
everything except the image data from any PNG, JPEG or GIF image it
prepares for Web view. Other software may do the same, but I can’t say
for certain. If you are using a server-side image resize/conversion
system like ImageMagick, then there are flags you can set on the
server to ensure that these metadata are properly stripped from the
As to whether IE or other browsers still reliably crash in the
presence of these tags, I can only say that it used to be reliably
true, and may have been fixed by the browsers at some point in the
last 10 years. But since Photoshop still strips this stuff out, I
would err on the side of caution and make sure you do the same if
you’re not using Save for Web (or Freeway’s normal image processing
workflow – non-pass-through).
On Aug 9, 2011, at 7:54 AM, tedg wrote:
Supposing that I use 100% pass-through images…
Other than download sizes, what are the penalties of not ‘cleaning’
PNG and JPG images?
I am specifically thinking of embedded previews and IPTC info.
Heard (from a trusted source) that IPTC data could crash IE, I
suppose old versions.
The biggest concern I would have is what I’ve heard called “unintentional disclosure of information”.
Imagine the scenario where you take some shots of something precious to you (valuables, children, family, whatever) and share these shots with the world online. Without you knowing it your camera could well have added geo location meta data to the images which would pin-point the item to a couple of hundred feet allowing anyone who wanted to dig deeper to pin point the exact location of the items in the images.
Obviously having this data embedded in certain images can be a real bonus. If you want viewers to know where the shot was taken of that stunning sunset or waterfall then great. There are some situations, as I’ve outlined above, where you may decide to remove the embedded meta data.
Simply open the image up in Preview, open the Inspector palette (Tools > Inspector) and select the More Info and GPS tabs.
There are numerous tools that will allow you to view, set and remove meta data from within images. Exiftool (for example) is a very powerful (if not a little intimidating) command line tool that will do everything you want with image metadata; http://www.sno.phy.queensu.ca/~phil/exiftool/
On 9 Aug 2011, at 12:54, tedg wrote:
Other than download sizes, what are the penalties of not ‘cleaning’ PNG and JPG images?