Which Exif are usefull for image processing?

[feelart]

Normally one strips the EXIF.
But, are some usefull to keep to perform image processing?
Maybe, just these two?
%Q
identify -format '%[exif:orientation]

Are focus point & white balance, lens, aperture information, useful ??

See also
viewtopic.php?f=1&t=23712&p=100433#p100433
http://www.imagemagick.org/Usage/photos/#exif
http://photo.stackexchange.com/question ... -exif-tags


In the end,if one only wants to keep the date&time and necessary EXIF, what's the command line to do so?

[GreenKoopa]

If you use it, it is useful. I do sometimes look at the EXIF data when deciding how to adjust a photo, although never in an automated way. I also use it in learning how to take better photos in the future.

There are tools that will take a jpeg and automatically rotate it, optimize the compression, and strip the thumbnail or other metadata. These jpeg specific tools are not only fast, they do all of this with perfectly zero loss of quality (or losslessly).

[snibgo]

When processing raw photos, I use ISO to determine noise reduction, and white balance to (possibly) determine white balance, and the lens ID to determine geometric distortion and chromatic aberation.

[GreenKoopa]

Why remove it? Are you looking for privacy or to save disk space?

I believe the latest Photoshop reads the EXIF data to automatically load lens correction settings. My cheap digital camera isn't supported and doesn't support raw or interchangeable lenses, but I can use focal length to get reasonable settings. And I also use ISO.

[snibgo]

I'll also mention that I find the metadata very useful when reviewing my photographic technique. Modern cameras have many controls -- aperture, shutter speed, ISO, exposure compensation, meter modes, auto-focus type (although I rarely use auto-focus), white balance, flash settings -- and when a picture doesn't work, I want to know why. For example, if there is camera shake I want to know the shutter speed so I can do it better next time.

For keeping/changing/removing metadata, I use exiftool. Not the easiest program in the world, so I create standard Windows script files. For example, to list all metadata:

Code: Select all

exiftool -s2 -all -b -X -fXMP:XMP %1.%EXT%>%1_allMeta.txt

To strip all metadata and add a copyright, for internet publishing:

Code: Select all

call setYear
exiftool -all= "-copyright=(c) %year% snibgo applied arts" %1
del *.jpg_original

[feelart]

OK, my prime question was badly formulated, I agree when working on the source shot.

But as soon as for instance, one applies some transformations, for example:

Code: Select all

convert -auto-orient -crop 2752x2168+1300+600 -normalize -resize 1980x1980

What EXIF are still correct and usefull to keep, or if you prefer should be deleted because incorrect?

>Why remove it? Are you looking for privacy or to save disk space?
Save disk space and keep was is still right.

[fmw42]

I suspect there is no good answer. Each processing step will affect different camera properties. Some processing steps may invalidate only some of the properties, while others may still be useful. It will depend upon what you do to process the image.