How to strip EXIF except "date taken" using Imagemagick? - image-processing

Question

I want to reduce image size by stripping EXIF metadata (convert -strip ...), but the problem is I want to preserve the "date taken" entry. Is it possible? For example: convert -quality 80 -strip-except "date taken" source.jpg dest.jpg

Answer 1

It depends how important it is to save the "date taken" "in the correct place" where it can be parsed by normal image viewing programs. If you just want the original date/time in the file somewhere/anywhere, you can extract it and save it in the "Comment" field like this:
# Use ImageMagick to get the exif:DateTime, e.g. "exif:DateTime: 2014:12:23 13:51:00"
d=$(identify -verbose image.jpg | grep "exif:DateTime:")
# Strip EXIF but then put DateTime in the "Comment" field
convert image.jpg -strip -set comment "$d" result.jpg
Update
Actually, you can get the date/time more succinctly, and in a platform-independent way than above by using:
identify -format "%[EXIF:DateTime]" image.jpg
2014:12:23 13:51:00
The date and time are now in the "Comment" field, it's just that ImageViewers won't find it there - although you can with:
identify -verbose result.jpg
Image: result.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Mime type: image/jpeg
Class: DirectClass
Geometry: 3264x2448+0+0
Resolution: 72x72
Print size: 45.3333x34
Units: PixelsPerInch
Type: TrueColor
Endianess: Undefined
Colorspace: sRGB
Depth: 8-bit
Channel depth:
red: 8-bit
...
...
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 3264x2448+0+0
Dispose: Undefined
Iterations: 0
Compression: JPEG
Quality: 96
Orientation: Undefined
Properties:
comment: exif:DateTime: 2014:12:23 13:51:00
A better way to do it though is using jhead. It has these options:
-ft Set filetime to EXIF time
-purejpg Strip EXIF, IPTC and other meta-data
-mkexif Create a minimal EXIF section
-dsft Set EXIF time to filetime
which you can string together as you wish, but probably in the order I have shown.