EXIF data

Camera lucida · 10-08-2008, 01:02 AM

What happens to the EXIF data after an image is resized?

*egordon99* · 10-08-2008, 06:31 AM

Assuming you're just using regular old Photoshop to change the image size, nothing.

Wheatfield · 10-08-2008, 07:25 AM

Originally Posted by Camera lucida

What happens to the EXIF data after an image is resized?

It sits there, taking up space in the maker notes part of the file, which is unaffected by resizing. If you are sizing images for the web, it is a nice idea to use the "Save for Web" option in Photoshop, as it strips out the EXIF data, which can take as much as 50K off the file size.

Marc Sabatella · 10-08-2008, 09:07 AM

Originally Posted by Wheatfield

If you are sizing images for the web, it is a nice idea to use the "Save for Web" option in Photoshop, as it strips out the EXIF data, which can take as much as 50K off the file size.

On the other hand, many of us like the option of being able to view EXIF for images that interest us. So unless you're deliberately trying to prevent people from knowing what camera you used or what aperture and shutter speed you had set, or are *extremely* cramped for space, or are worried about download speeds for people with 300 baud modems, I recommend people *not* use the "Save for Web" option.

Wheatfield · 10-08-2008, 07:23 PM

Originally Posted by Marc Sabatella

On the other hand, many of us like the option of being able to view EXIF for images that interest us. So unless you're deliberately trying to prevent people from knowing what camera you used or what aperture and shutter speed you had set, or are *extremely* cramped for space, or are worried about download speeds for people with 300 baud modems, I recommend people *not* use the "Save for Web" option.

I do worry about wasting people's bandwidth, far more than I worry about people downloading my pictures for no reason other than to satisfy their idle curiosity. When I post images on the Pentax mail list, it is by link, and I include the pertinent information (shutter speed, aperture, lens and camera used in the email. This is a few bits of data transmission rather than the 50 or so kilobytes that the EXIF data takes up.
Consider that if I post a picture a day to my website and get 200 hits per picture, how much extra bandwidth my server has to use per month to transmit the EXIF data, which isn't really pertinent to the picture itself.

One of the major annoyances of this forum (other than people who disagree with me) is opening a thread I've been following, only to find out that someone has posted huge image files into it for no apparent reason.
To me, this is the pinnacle of internet self centered rudeness.

Camera lucida · 10-08-2008, 07:49 PM

The reason why I posted this thread is the upcoming Pentaxian day on Saturday.
If I decided to post a photo and have to resize it to 800 pixels on the longest side and then save it for web, how are the organisers going to know when the photo was taken, if resizing and saving for web strips out the EXIF data?
(Jeez - what a long sentence).

Wheatfield · 10-08-2008, 07:58 PM

Originally Posted by Camera lucida

The reason why I posted this thread is the upcoming Pentaxian day on Saturday.
If I decided to post a photo and have to resize it to 800 pixels on the longest side and then save it for web, how are the organisers going to know when the photo was taken, if resizing and saving for web strips out the EXIF data?
(Jeez - what a long sentence).

If you need the EXIF data imbedded, then leave it in by using "Save As" rather than "Save for Web".
This is a fairly simple decision to make.

HGMonaro · 10-08-2008, 08:15 PM

It depends on the software... I use PS7 and I'm pretty sure it removes EXIF info regardless of the saving method. If you'd like to buy me a new copy, I'll ensure my EXIF's stay intact

*ChipB* · 10-08-2008, 09:05 PM

I use one of two methods for resizing - Microsoft's resizing tool (part of Microsoft Power Toys for XP - a tool package) or Fast Stone Image Viewer.

Does anyone know if either or both leave the EXIF data intact? Thanks.

*FHPhotographer* · 10-08-2008, 09:15 PM

Originally Posted by Wheatfield

I do worry about wasting people's bandwidth, far more than I worry about people downloading my pictures for no reason other than to satisfy their idle curiosity. When I post images on the Pentax mail list, it is by link, and I include the pertinent information (shutter speed, aperture, lens and camera used in the email. This is a few bits of data transmission rather than the 50 or so kilobytes that the EXIF data takes up.
Consider that if I post a picture a day to my website and get 200 hits per picture, how much extra bandwidth my server has to use per month to transmit the EXIF data, which isn't really pertinent to the picture itself.

One of the major annoyances of this forum (other than people who disagree with me) is opening a thread I've been following, only to find out that someone has posted huge image files into it for no apparent reason.
To me, this is the pinnacle of internet self centered rudeness.

I agree that redundant posting of images from folks too lazy to take them out is annoying.

However, I can't agree about exif. I guess it depends on whose ox is being gored; I find it very frustrating to find posted images that have the exif stripped. If posts to a photogaphy site, they want the image and the artistry to be appreciated and/or critiqued. If they don't want to tell me some basics about the method by including exif data, they shouldn't be on photography sites. Or so it seems to me,
Brian (FHPhotographer)

Wheatfield · 10-08-2008, 10:09 PM

Originally Posted by FHPhotographer

I agree that redundant posting of images from folks too lazy to take them out is annoying.

However, I can't agree about exif. I guess it depends on whose ox is being gored; I find it very frustrating to find posted images that have the exif stripped. If posts to a photogaphy site, they want the image and the artistry to be appreciated and/or critiqued. If they don't want to tell me some basics about the method by including exif data, they shouldn't be on photography sites. Or so it seems to me,
Brian (FHPhotographer)

Good point.
For my personal stuff, I am putting forwards an image, to be accepted or no, on it's merits, not for whatever camera, lens or f stop I chose to use to produce it. If I am posting something to make a point, for example, then I would leave EXIF intact, but for an art picture, I just don't see the point.

Wheatfield · 10-08-2008, 10:12 PM

Originally Posted by ChipB

I use one of two methods for resizing - Microsoft's resizing tool (part of Microsoft Power Toys for XP - a tool package) or Fast Stone Image Viewer.

Does anyone know if either or both leave the EXIF data intact? Thanks.

You can download a free version of PhotoMe and use it to check EXIF data of image files.
I suspect that most image editors leave EXIF intact. I'm pretty sure that PS7 does, but to be sure, I would have to install it and check.

PDL · 10-09-2008, 12:18 AM

On some sites - including this one - EXIF is stripped out by some automagic system. Since I embed my copyright in the IPTC fields, I find it very frustrating when my EXIF is stripped. I know that the EXIF is intact before uploading because I check it with the Pentax codec in Vista, MS explorer properties and Photome. It is there but for the last few months it has been stripped out when uploading to this site. Just use Photome on the monthly contest - a lot of missing data.

Now, that said, normally I don't really give a rip about the so-called details. I am more interested in the subject, composition and such rather than what lens was used. Now, if the poster is making some claim about DOF, focus point, high/low ISO quirks etc. then the EXIF information is interesting. When I attend workshops, the hardware is hardly ever discussed -- it is all about the image. During the last workshop I attended, we spent 20-30 minutes talking camera hardware - the rest of the 5 days we talked about how to improve our images.

Hardware is secondary - it's the image content that counts.

The Elitist - formerly known as PDL

Zebooka · 10-09-2008, 02:16 AM

Originally Posted by egordon99

Assuming you're just using regular old Photoshop to change the image size, nothing.

Wrong. Photoshop (as well as other known programs) kills MakerNote tag in EXIF.
This tag contains vital data such as ShutterCount, camera temperature, internal serial number etc.

Wheatfield · 10-09-2008, 07:53 AM

Originally Posted by Zebooka

Wrong. Photoshop (as well as other known programs) kills MakerNote tag in EXIF.
This tag contains vital data such as ShutterCount, camera temperature, internal serial number etc.

That's because EXIF data is standardized, but Maker Notes are proprietary to the camera manufacturer.
I tend to distrust Wikipedia, but here is a link anyway:
EXIF Maker Notes - ptWiki