First of all, I wouldn't use a hex editor, but use an existing tool, such as Phil's exif tool.
Orientation is an exif tag 0x0112 *Orientation* int16u IFD0 1 = Horizontal (normal) 2 = Mirror horizontal 3 = Rotate 180 4 = Mirror vertical 5 = Mirror horizontal and rotate 270 CW 6 = Rotate 90 CW 7 = Mirror horizontal and rotate 90 CW 8 = Rotate 270 CW Regards Sherwood On Wed, 29 Jan 2020 at 11:42, Myron Gochnauer <[email protected]> wrote: > Hi Sherwood, > > Thanks for the advice and info. Very helpful. > > I was aware of some of the risks of using a hex editor to change program > files (and similar files). For a few years back in the early/mid 80's I had > to tweak my favorite word processor (XyWrite) so that it would work with a > Hyperion computer, whose character table was non-standard. I seem to > recall tweaking a modem driver too. (300 baud. Wow! I could read email > messages as they scrolled in. Pre-spam days… sigh.) > > Re image orientation numerical values: How can I find out what numbers > are "generally regarded as meaningful"? I would expect any competently > written program to handle out-of-range numbers 'gracefully' as long as they > occupied the same number of bits. (Graceful = ignore or substitute a > default, with or without an error message) > > I like your 'extended copyright' idea. Would you be willing to share the > script you use replace the placeholding X's? I assume you automate the > ExifTool??? Looking at ExifTool's instructions and examples is near the > top of my "I've gotta learn that!" list (up there with Brahms Op.79, > controlling DC motor speeds, and figuring out the network wiring in my > house). 🙂 > > (On Mac, I use A Better Finder Rename to rename imported raw files to Exif > date & time, making on-disk file organization by date/time dead simple, > but I don't think it gives access to other exif data.) > > Myron > > > ------------------------------ > *From:* Sherwood Botsford <[email protected]> > *Sent:* January 29, 2020 12:16 PM > *To:* dt-user list <[email protected]> > *Subject:* Re: [darktable-user] Semi-OT: setting orientation > > > ✉External message: Use caution. > If you are going to experiment with editing raw files, some risk factors: > > From reading Phil's exif web site, and other stuff I didn't bookmark > corruption risk: > > Safest: > 1. Editing standard metadata (Exif, ITPC) replacing a value with one of > the same size. Image orientation would be one of these, I think, having a > value of 0-3 (but check the range. Suppose it is 0 to3 and you put in 5? > Will other software ignore it, only pay attention to the smallest two bits > of the number, interpreting it as a 1, go wandering off into a cloud of > blue bits and crash?) > 2. Editing standard metadata replacing a value with one that is smaller. > Some fields are text strings, and so can be padded with blanks, changing > the problem to that of problem 1. > 3. Editing makernotes data. This is propriatary to the camara maker, and > it's format can vary with both model and firmware version. > 4. Editing preview images. The big risk here is that the size of the > preview will change, and whatever you edit with won't leave the end of the > data in the same place, potentially clobbering the front end of the raw > data. > 5. Editing uncompressed raw data. > 6. Editing compressed raw data. > Most risky. > > One of my ideas is to deliberately in my camera put an extended copyright > notice such as > > Copyright S. G. Botsford 2020 -- Image ID > Nikon-D7100-S.7614346-XXXX-XXXX-XXXX-XXXX-XXXX > > Then, with a script read the exif date, and the shutter count, and replace > the string of X's with the date and shutter count. > > This gives a unique ID trackable back to me for the image. I don't know > if all cameras write an ITPC core section in the meta data, or if this > field is in the maker notes. > > In all derived files, copy this information to a few other fields. Not > all photo editors respect metadata. Your image database tracks this. > > * You edited a bunch of images with Photoshop, saved under different > names. -- you still have a way to connect the .PSD, the resulting TIFF > with the original RAW. > * Your assistant used a file browser to "organize" your image archive. -- > you can reconnect xmp files with masters. > * Your database has crashed, taking everything with it. XMP files can be > reconnected with masters even if names are in doubt. > * You exported a bunch of images. Someone wants a modification that will > work better if starting from the original. > > It doesn't work for all cameras. iPhones don't have a shutter count, nor > AFAIK a raw format available to the public. > > > > Regards > > Sherwood > > > > On Wed, 29 Jan 2020 at 05:43, Patrick Shanahan <[email protected]> wrote: > > * Myron Gochnauer <[email protected]> [01-29-20 03:05]: > > Several people suggested trying exiftool… carefully!! (I’ve been burned > often enough to know you only experiment on copies.) > > > > Anyway, exiftool -a -u -g1 {fname} showed the following results: > > > > “Orientation : Horizontal (normal)” - - - in exif of NEF landscape > format image file. > > > > "Orientation : Rotate 270 CW” - - - in exif of RAF portrait format image > file. > > > > I’ll see if I can figure out how to edit those values. (I’m a total > newbie with exiftool.) > > > > It *does* seem like there is a place for a GUI app, complete with error > checking, for altering exif information. If nothing else, I’m pretty sure > that *everyone* sooner or later produces a bunch of images with last year’s > copyright information, the wrong time, or some other annoying error. > > A "mantra" of darktable is to not touch in any way the "raw" image. > Editing with exiftool or exiv2 both will make changes to the "raw" image > file with unknown now or future consequences. > > You by using darktable have opted to use a photo editor which does not > change in any way the "raw" image. Why contradict that by makeing changes > with another apt? > > It is no more work to rotate the images using darktable. And darktable > will store the image orientation that you determine within the xmp file > and the library. Maintain backups of your library and your raw image > files and their accompanying xmp files and your orientation will also be > retained. > > Do what you want with exported images, you have an original now so you can > always make another. > > And a bonus, no need to research exiftool/exiv2 and craft commandline > parameters to rotate your images. > > ps: does your chosen email client not make line wrapping available for > you? Maybe time to change. > > > -- > (paka)Patrick Shanahan Plainfield, Indiana, USA @ptilopteri > http://en.opensuse.org openSUSE Community Member facebook/ptilopteri > Photos: http://wahoo.no-ip.org/piwigo paka @ IRCnet freenode > > ____________________________________________________________________________ > darktable user mailing list > to unsubscribe send a mail to > [email protected] > > > ____________________________________________________________________________ > darktable user mailing list to unsubscribe send a mail to > [email protected] > ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to [email protected]
