Go Back   Steve's Digicams Forums > Digicam Help > Newbie Help

Reply
 
Thread Tools Search this Thread
Old Oct 30, 2010, 4:40 PM   #1
Senior Member
 
maryintexas39's Avatar
 
Join Date: Dec 2009
Location: texas
Posts: 397
Default A question about EXIF data

Why do some of the editing software strip the EXIF data? For instance if I resize a photo in Picasa, Picnic or Photolightning and post the resized photo in a forum here on Steve's, the EXIF data is usually stripped .

Thanks,
__________________

maryintexas39
**************
Panasonic DMC-LX5/Panasonic Lumix ZS9/Panasonic Lumix ZS15

my flickr: http://www.flickr.com/photos/maryintexas39/
maryintexas39 is offline   Reply With Quote
Sponsored Links
Old Oct 30, 2010, 7:26 PM   #2
Senior Member
 
VTphotog's Avatar
 
Join Date: Mar 2005
Location: Extreme Northeastern Vermont, USA
Posts: 4,214
Default

I can't say for sure, but some may do it to help reduce file size, or possibly to protect your privacy. Or it may just be simpler to write the software without considering exif.
With some programs, such as Irfanview, you can choose whether to include the exif. Most of the more advanced editors have this ability.

brian
VTphotog is offline   Reply With Quote
Old Oct 31, 2010, 9:15 AM   #3
Senior Member
 
BillDrew's Avatar
 
Join Date: Jun 2002
Location: Hay River Township, WI
Posts: 2,512
Default

Simpler programming is likely the answer - if you look at various EXIF readers for your camera you will likely find that they don't all produce the same amount of detail, e.g., focus distance, shutter speed in both fraction and decimal format, ...

The EXIF data takes up something like 50-100K if the thumbnail is included which can be significant if there are a large number on a web page or if the user is on a dial-up connection.
BillDrew is offline   Reply With Quote
Old Oct 31, 2010, 9:21 AM   #4
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Quote:
Originally Posted by maryintexas39 View Post
Why do some of the editing software strip the EXIF data? For instance if I resize a photo in Picasa, Picnic or Photolightning and post the resized photo in a forum here on Steve's, the EXIF data is usually stripped .
It may not be your software. Have you looked to see if the EXIF is still in the photos you've downsized before you attach them to a post here?

If so, then the forums software is stripping it out. When you use the Attachments Manager here at Steve's to upload images to our Forum Servers, you'll see maximum sizes shown for dimensions and file sizes in the screen that comes up that lets you browse and attach images from your PC's hard drive. Many users don't pay any attention to it and exceed the maximum allowed sizes.

Right now, those maximums are set so that the image dimensions should be no larger than 1024 pixels on their longest side, and the file size should be no larger than 253.9KB (260,000 bytes).

If your images are larger than the maximum sizes we allow, the uploads will usually still work. But, the forums software will attempt to resize and recompress the images so that they meet the forum requirements. The EXIF is also stripped out during that process.

So, if you don't want your images being modified by the forums software, make sure you downsize them so that both the dimensions and the file size are within the maximum allowed sizes for image attachments. Usually (and image content will impact how well a jpeg image compresses), if you downsize an image so that it's 1024 pixels or smaller on the longest side, and use a JPEG Quality (compression) setting of around 80%, that will keep the images within the maximum allowed sizes. You should find a slider in your software that controls JPEG Quality (compression amount) when you downsize an image.
JimC is offline   Reply With Quote
Old Oct 31, 2010, 9:40 AM   #5
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Quote:
Originally Posted by JimC View Post
...Right now, those maximums are set so that the image dimensions should be no larger than 1024 pixels on their longest side, and the file size should be no larger than 253.9KB (260,000 bytes).
P.S.

Keep in mind that many users don't have higher resolution displays (the most common display size is still 1024 x 768 pixels if you look at most statistics keeping track of that kind of thing).

http://gs.statcounter.com/#resolutio...-200910-201010

You also have members browsing forums with netbooks and even smart phones. So, even an image that's 1024 pixels on it's longest side can make it difficult for some members to see the entire image without scrolling.

If file sizes are too large, that can also cause problems for members, as we still have a number of members that don't have high speed internet access (with a number of them still using dialup access). Also, some wireless data plans are not unlimited and have bandwidth usage restrictions (i.e., based on how much data is downloaded in kilobytes). So, larger image file sizes increase member costs in those cases (using more of the bandwidth on the data plan they have), and can cause longer page load times with large image sizes (especially if more than one image is on a page).

Not too long ago, we used to recommend images be no larger than 640 x 480 pixels. Here's an old post on the subject (the instructions are no longer valid, since we've changed forums software since then).

http://forums.steves-digicams.com/ge...ur-photos.html

Right now, we have the forums set for a maximum size of 1024 pixels on the longest side of an image, with a max file size of 253.9KB. But, keep in mind that that's still considered to be large when users don't have high speed internet access, or have a usage based data plan. Ditto for trying to view a larger image on a smaller screen (netbooks, smart phones, etc.) without needing to scroll to see all of it.

IOW, please don't assume everyone has the latest and greatest high resolution display, and an unlimited usage high speed internet plan when posting images here. ;-)
JimC is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 9:05 PM.