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EXIF inconsistency
This seems very strange, and I'd appreciate any suggestions as to the
cause please. In IrfaNview 3.95 I viewed a JPG. First the original HD file and then the identical file burned to a CD with Nero. All EXIF entries are identical *except* the following 3 (and the File path of course): Value........ EXIF Tag From HD From CD --------- ------- ------- ExifImageWidth 1360 2048 ExifImageHeight 2048 1360 InteroperabilityOffset 531 582 I don't know what 'InteroperabilityOffset' is, but I can say that the HD version is correct and the CD version incorrect on the first two entries, as this was a photo in portrait mode. FWIW, here are the other identical tags: EXIF Tag Value -------- ------ Make SONY Model CYBERSHOT Orientation Top left XResolution 72 YResolution 72 ResolutionUnit Inch DateTime 2004:04:05 11:18:48 YCbCrPositioning Co-Sited ExifOffset 224 ExposureTime 1/626 seconds FNumber 5.60 ExposureProgram Normal program ISOSpeedRatings 100 ExifVersion 0210 DateTimeOriginal 2004:04:05 11:18:48 DateTimeDigitized 2004:04:05 11:18:48 ComponentsConfiguration YCbCr CompressedBitsPerPixel 2 (bits/pixel) ExposureBiasValue 0.00 MaxApertureValue F 2.83 MeteringMode Center weighted average LightSource Auto Flash Not fired FocalLength 9.20 mm FlashPixVersion 0100 ColorSpace sRGB FileSource DSC - Digital still SceneType A directly photographed image I've also emailed IrfanView's author. -- Terry, West Sussex, UK |
#2
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"Terry Pinnell" wrote in message ... This seems very strange, and I'd appreciate any suggestions as to the cause please. In IrfaNview 3.95 I viewed a JPG. First the original HD file and then the identical file burned to a CD with Nero. All EXIF entries are identical *except* the following 3 (and the File path of course): Value........ EXIF Tag From HD From CD --------- ------- ------- ExifImageWidth 1360 2048 ExifImageHeight 2048 1360 InteroperabilityOffset 531 582 I don't know what 'InteroperabilityOffset' is, but I can say that the HD version is correct and the CD version incorrect on the first two entries, as this was a photo in portrait mode. FWIW, here are the other identical tags: EXIF Tag Value -------- ------ Make SONY Model CYBERSHOT Orientation Top left XResolution 72 YResolution 72 ResolutionUnit Inch DateTime 2004:04:05 11:18:48 YCbCrPositioning Co-Sited ExifOffset 224 ExposureTime 1/626 seconds FNumber 5.60 ExposureProgram Normal program ISOSpeedRatings 100 ExifVersion 0210 DateTimeOriginal 2004:04:05 11:18:48 DateTimeDigitized 2004:04:05 11:18:48 ComponentsConfiguration YCbCr CompressedBitsPerPixel 2 (bits/pixel) ExposureBiasValue 0.00 MaxApertureValue F 2.83 MeteringMode Center weighted average LightSource Auto Flash Not fired FocalLength 9.20 mm FlashPixVersion 0100 ColorSpace sRGB FileSource DSC - Digital still SceneType A directly photographed image I've also emailed IrfanView's author. -- Terry, West Sussex, UK FWIW, my camera (S1 IS) puts the orientation (P/L) in the EXIF file and displays the thumbnail oriented correctly (viewfinder/LCD screen) when reviewed in the camera. Some other software also automatically rotates (JAlbum, for one). Although I use IrfanView for quick viewing and slide shows on my PC, I use either Exifer (which shows 35mm 'equivalent' focal lengths/viewpoints? with the zoom multiplier relative to the shortest focal length & the digital zoom multiplier seperately) and Exif Viewer, which doesn't how the real zoom multiplier but does have the useful picture comparison & statistics options. http://www.exif.org/ is a useful site for info :- "EXIF.org is a site dedicated to EXIF and related resources. EXIF stands for Exchangeable Image File Format, and is a standard for storing interchange information in image files, especially those using JPEG compression. Most digital cameras now use the EXIF format. The format is part of the DCF standard created by JEIDA to encourage interoperability between imaging devices. " |
#3
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"Terry Pinnell" wrote in message ... This seems very strange, and I'd appreciate any suggestions as to the cause please. In IrfaNview 3.95 I viewed a JPG. First the original HD file and then the identical file burned to a CD with Nero. All EXIF entries are identical *except* the following 3 (and the File path of course): Value........ EXIF Tag From HD From CD --------- ------- ------- ExifImageWidth 1360 2048 ExifImageHeight 2048 1360 InteroperabilityOffset 531 582 I don't know what 'InteroperabilityOffset' is, but I can say that the HD version is correct and the CD version incorrect on the first two entries, as this was a photo in portrait mode. FWIW, here are the other identical tags: EXIF Tag Value -------- ------ Make SONY Model CYBERSHOT Orientation Top left XResolution 72 YResolution 72 ResolutionUnit Inch DateTime 2004:04:05 11:18:48 YCbCrPositioning Co-Sited ExifOffset 224 ExposureTime 1/626 seconds FNumber 5.60 ExposureProgram Normal program ISOSpeedRatings 100 ExifVersion 0210 DateTimeOriginal 2004:04:05 11:18:48 DateTimeDigitized 2004:04:05 11:18:48 ComponentsConfiguration YCbCr CompressedBitsPerPixel 2 (bits/pixel) ExposureBiasValue 0.00 MaxApertureValue F 2.83 MeteringMode Center weighted average LightSource Auto Flash Not fired FocalLength 9.20 mm FlashPixVersion 0100 ColorSpace sRGB FileSource DSC - Digital still SceneType A directly photographed image I've also emailed IrfanView's author. -- Terry, West Sussex, UK FWIW, my camera (S1 IS) puts the orientation (P/L) in the EXIF file and displays the thumbnail oriented correctly (viewfinder/LCD screen) when reviewed in the camera. Some other software also automatically rotates (JAlbum, for one). Although I use IrfanView for quick viewing and slide shows on my PC, I use either Exifer (which shows 35mm 'equivalent' focal lengths/viewpoints? with the zoom multiplier relative to the shortest focal length & the digital zoom multiplier seperately) and Exif Viewer, which doesn't how the real zoom multiplier but does have the useful picture comparison & statistics options. http://www.exif.org/ is a useful site for info :- "EXIF.org is a site dedicated to EXIF and related resources. EXIF stands for Exchangeable Image File Format, and is a standard for storing interchange information in image files, especially those using JPEG compression. Most digital cameras now use the EXIF format. The format is part of the DCF standard created by JEIDA to encourage interoperability between imaging devices. " |
#4
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Terry
In IrfaNview 3.95 I viewed a JPG. First the original HD file and then the identical file burned to a CD with Nero. All EXIF entries are identical *except* the following 3 (and the File path of course): I'm not sure what you mean when you say the "identical" file. Is it just a straight copy of the jpeg file onto CD or did you use some photo-aware package to make the CD copy? If you just did it by, say, dragging and dropping the HD file into Nero, no way can the EXIF data be different. Applications like Nero just copy files as lumps of arbitrary data and wouldn't recognise an EXIF header if one jumped out and bit it. A file copied to CD by Nero should be byte-for-byte identical to the original. I don't know what 'InteroperabilityOffset' is... The header information on a photo contains a number of data structures called "Image File Directories" (IFDs). Each IFD can contain an arbitrary number of items. Information tends to be grouped into different IFDs depending upon type. For example, there are separate IFDs for information pertaining to the main image and the thumbnail (if present). All the camera settings (exposure etc.) will be in another IFD called, surprise surprise, the Camera Information IFD. One of the IFD's is called the "interoperability IFD" and contains, according to the EXIF spec, "tags which store information to ensure interoperability" (whatever that means). The Interoperability offset is simply the offset of the interoperability IFD within the jpeg file, telling processing software where to find this data. Quite _why_ I should want to find the interoperability IFD I don't know, because I've never found any useful information in it. When creating a photo file, application software and cameras have a lot of flexibility what to store where in which IFD, and the order of the data. Applications and cameras can also insert arbitrary "padding" into the file between data blocks. Cameras frequently do this to keep important information at fixed offsets. This helps to keep the camera firmware simpler and therefore smaller. It is therefore possible for the "same" photo with the "same" header info to have wildly differing file sizes and/or to store the header information in completely different orders. EXIF Tag From HD From CD InteroperabilityOffset 531 582 What this says is that the Interoperability IFD is 51 bytes further up the file on the CD compared with the file on the HD. This implies to me that some sort of photo-aware application package has processed the file before it was stored on CD. Keith |
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