PDA

View Full Version : Strange EXIF values


peppies
February 18th, 2008, 06:10 AM
Hello all,

can anyone please explain the strange EXIF values I'm getting in my VBGallery? Why such an important thing as Aperture is not there at all? All I really want displayed are basic camera settings for each photo. Have a look at my attachment.

Can this be modified? Highlighted fields are the values that don't make much sense to me. Thank you.

Chuck S
February 18th, 2008, 08:49 AM
What do you think are wrong with that info? Basically your camera is writing the exif info to the photos you take and we simply extract it from the image when we process it.

peppies
February 18th, 2008, 09:16 AM
Hi Chuck,

Well, the way it's interpreted is just wrong. For example focal length 800/10 should be 80 mm. Exposure time 10/2500 should simply be 1/250s, metering mode "5" should say "multi-segment" and so on. The same photo shows EXIF perfectly in any other application. This is not just example of one photo's weird EXIF. All images in a gallery from all users show numbers similar to that. And there is aperture F number missing which is important to have.

Have a look at this EXIF shown from IrfanView. Everything makes sense (it's different photo):

Make - Canon
Model - Canon EOS 30D
Orientation - Top left
XResolution - 72.00
YResolution - 72.00
ResolutionUnit - Inch
Software - Adobe Photoshop CS3 Windows
DateTime - 2007:12:19 21:05:46
YCbCrPositioning - Co-Sited
ExifOffset - 220
ExposureTime - 1/60 seconds
FNumber - 5.60
ExposureProgram - Portrait mode
ISOSpeedRatings - 400
ExifVersion - 0221
DateTimeOriginal - 2007:12:19 14:32:43
DateTimeDigitized - 2007:12:19 14:32:43
ComponentsConfiguration - YCbCr
ShutterSpeedValue - 1/60 seconds
ApertureValue - F 5.60
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Flash fired, auto mode
FocalLength - 68 mm
UserComment -
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 2870
ExifImageHeight - 1913
InteroperabilityOffset - 920
FocalPlaneXResolution - 3959.32
FocalPlaneYResolution - 3959.32
FocalPlaneResolutionUnit - Inch
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
SceneCaptureType - Standard

Thumbnail: -
Compression - 6 (JPG)
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
JpegIFOffset - 1046
JpegIFByteCount - 4520

Can at least main parameters be shown correctly?

Chuck S
February 18th, 2008, 09:32 AM
We dont interpret data in any manner nor can be make things appear any different than your camera imprints them on the photo. Basically this is up to your camera. Your camera writes the name and value of a field in an array and imprints it on the photo. Whether using jhead or exif function of php that simply takes the data in an array from the image and reads the variables and we write the data into the database

http://us.php.net/exif

You cant change what your camera has imprinted on the image. Now you may want to investigate whether your camera can show information in different formats.

peppies
February 18th, 2008, 09:40 AM
I understand what you're saying, but how come the PhotoPost is able to interpret the EXIF correctly? Example: http://www.donwoodphoto.com/showphoto.php/photo/7398

You can see Shutter speed, focal length, aperture white balance and everything else properly. Why I cannot have EXIF like that in VbGallery?

Chuck S
February 18th, 2008, 09:52 AM
Thats not much of a comparison there as those are two different programs using different exif programs and even different cameras which most likely write the information differently.

Photopost Pro = jhead = canon powershot

vbGallery = exif in php = Nikon Camera

You would have to use the same camera and same photo and upload it to a vbgallery and a photopost site and see the difference and then again it comes down to one uses jhead as the exif extractor and one uses php's exif function. So literally there is no comparison. The end result is we have no control over what is written to a photo and what the extractor that is used extracts or what info a camera writes to a photo.

peppies
February 18th, 2008, 10:27 AM
So there is no way to interpret for example
FNumber: 32/10 to show FNumber: 3.2?

Chuck S
February 18th, 2008, 10:31 AM
Not that I am aware of. Your using vbGalley and php exif function with a nikon.

Your other example is Photopost Pro which uses jhead not php exif and a canon camera.

Both functions that I see just strip the info the camera writes to the photo and inserts it into the database for display. This is more so probally an issue of how your camera model writes the exif data than anything else. Your Nikon which is probally a very expensive efficient model writes exif in true values and that canon sureshot which is a cheap model probally writes data in short hand values. Probally the difference in comparing a samsung tv versus an rca tv.

peppies
February 18th, 2008, 10:59 AM
Chuck I'm afraid it has nothing to do with the camera model.

Same photo in PhotoPost shows Focal length correctly: 4.6mm
and in VbGallery it shows: 4600/1000. (which basically is the same value but format is just dreadful.)

I'm sorry to be a pain, but it's hard to believe that PHP interpretation of the same EXIF data is vastly different from the one jhead generated. It shows correctly in one but different in another? I've never seen focal length of 4600/1000. It's nonsense. Had tested expensive and cheap cameras to no avail.

Chuck S
February 18th, 2008, 11:08 AM
You can report this as a vbgallery bug for them to look at but from what I see in the code we simply use php exif in vbGallery and it simply grabs the info and displays it. php exif and jhead are functions and programs not written by us so I can not say how they interpret or display data.

peppies
February 18th, 2008, 11:21 AM
Thank you for responding so fast. Where can I report it?

Chuck S
February 18th, 2008, 12:03 PM
In the support forums under vbGallery section bugs. I do not beleive this to be a big since we are talking two separate exif processors but they will respond further. You can also upload one of your images to a photopost pro site to see how the exif is displayed. This will tell you if its the camera or the difference between using php exif over jhead. Now if jhead does what you want then your might need to run photopost pro as vbgallery does not use jhead.