LR 3.4: Export as JPEG, metadata using "quality" vs. "limit file size"
LRuser24 Apr 27, 2011 4:40 PMI found some unexpected differences between using "quality" and "limit file size" when exporting a RAW file (a Canon 40D CR2 in this case) as a JPEG with respect to the meta data in the exported file. Some of that was already present in 3.3 and 3.4RC, but now the following differences can be found in 3.4 final, which I just installed (WinXP, 32Bit). I think that this would be too long for the adobe bug report form, so it is perhaps better to post it here in the forum. I compared the meta data using exiftool. The tag names below are the "short" tag names used by exiftool.
- Differences between "quality" and "limit filesize" when "minimize embedded metadata" is OFF:
- With "quality", all brush strokes are included in what seems to be an XMP extension (?), but with "limit filesize", they are not included. However, with "limit filesize", one must still specify a file size greater than the metadata used by brush strokes, or the export will fail. I have an example here (many many brush strokes) that exports a file with 77K when the file size limit is set to 500K (and fails for 300K). This may be true for other local corrections, too - but I did not test that.
- With "quality", Exif tag "Software" with value "Adobe Photoshop Lightroom 3.4" is included, but with "limit filesize", it is not.
- With "quality", Exif tag "ExifVersion" equals "0230", but with "limit filesize", it equals "0221".
- With "quality", Exif tag "WhiteBalance" is NOT included, but with "limit filesize", it IS.
- With "quality", all Exif GPS tags are included, but with "limit filesize", they are not.
- With "quality", a thumbnail is included, but with "limit filesize", it is not.
- With "quality", XMP tag "ApproximateFocusDistance" is included, but with "limit filesize", it is not.
- With "limit filesize", XMP tags FlashFired, FlashReturn, FlashMode, FlashFunction, FlashRedEyeMode are included, but with "quality", they are not.
- Development settings are included in both, but with "limit filesize", they are in a "SavedSettingsParameters" variant, e.g. "quality": SaturationAdjustmentOrange, "limit filesize": SavedSettingsParametersSaturationAdjustmentOrange.
- With "quality", XMP tag "MetadataDate" seems to be the timestamp of the export (with time zone +02:00), but with "limit filesize", it seems to be the timestamp of the import (?), and with a different time zone (-02:00).
- With "quality", XMP tag "WhiteBalance" equals "Custom", but with "limit file size" (as "SavedSettingsParametersWhiteBalance", see above), it equals "As Shot" (but in LR, WB is set to "custom"!)
- Differences between "quality" and "limit filesize" when "minimize embedded metadata" is ON:
- Again, with "limit filesize", one must still specify a file size greater than the metadata used by brush strokes, or the export will fail - even though it was explicitely requested to minimize the metadata.
- With "quality", Exif tag "ExifVersion" is not present, but with "limit filesize", it equals "0221".
- Again, With "quality", a thumbnail is included, but with "limit filesize", it is not.
- With "limit filesize", the XMP tags WebStatement, UsageTerms, ExifImageWidth and ExifImageHeight are included, but with "quality", they are not.
- Last but not least, the following Exif tags are unexpectedly *included* with "limit filesize" - even though it was explicitely requested to minimize the metadata:
- Make (!!!)
- Model (!!!)
- ModifyDate
- ExposureTime
- FNumber
- ExposureProgram
- ISO
- DateTimeOriginal (!!!)
- CreateDate
- ShutterSpeedValue
- ApertureValue
- ExposureCompensation
- MaxApertureValue
- SubjectDistance
- MeteringMode
- Flash
- FocalLength
- SubSecTime
- SubSecTimeOriginal
- SubSecTimeDigitized
- FocalPlaneXResolution
- FocalPlaneYResolution
- FocalPlaneResolutionUnit
- CustomRendered
- ExposureMode
- WhiteBalance
- SceneCaptureType
- SerialNumber (!!!)
- LensInfo (!!!)
- LensModel (!!!)
- ... These are practically all Exif data that the camera provides. The ones marked with "!!!" may be relevant to data privacy when you think that "minimize embedded metadata" filters out all this critical stuff.
There may be other differences depending on images type and camera model. However, it seems that in general, "quality" and "limit filesize" behave completely different - but why??

