Unwriteable Metadata Tags Questions

[Metalsech]

Hi everyone. I've been trying out the Exiftool copy all metadata option (exiftool -all= -tagsfromfile FilePath1 -exif FilePath2) on a variety of images on multiple cameras and have noted that some tags it isn't able to copy across: FlashPix tags on images shot on Fujifilm cameras, Y Cb Cr Sub Sampling EXIF tag, Preview Image Size Composite tag, Samsung Trailer tags on Samsung phone images, JFIF tags on iPhone images.

Does anyone know the reason why these cannot be copied back across by ExifTool? Would it be possible to copy these back across using programming code or would this encounter the same blockers? If it would be possible can anyone provide any advice on this - code language this would be done in, links to any guides showing how to do this etc?

[StarGeek]

For FlashPix, exiftool doesn't have the ability to write any of those tags.  It may be possible to copy it as a block.  See last paragraph of FAQ #9.

YCbCrSubSampling can be copied, but it is marked as unsafe to copy.  You would have to explicitly copy it and doing so may affect the way the image is rendered.  See 4th paragraph on the Tag Names page.

PreviewImageSize is a Composite tag.  It doesn't actually exist. Exiftool creates it out of other existing tags.  You would have to copy the tags it is based upon.  I'm assuming that in your case, it would be based upon the FlashPix preview image.  It would probably appear if it's possible to copy the FlashPix block.

Samsung Trailer tags are not writable, though as with FlashPix, it may be possible to copy as a block.

Not all JFIF tags are writable.  Those that are can be copied.  Otherwise, you can copy as a block.