On Fri, Dec 4, 2015 at 11:50 PM, Jean-Luc CECCOLI <jean-luc.cecc...@wanadoo.fr> wrote: > Do you know of some place where I could find explanations on why modifying > information in raw files with tools that pretend to have been made for this > can be unsafe ? > > Could it be because the exif standard is not a standard at all (I mean that > each make does its own little soup inside the "standard") ?
EXIF is pretty standard and works fine. The problem is the raw files themselves. There's no standard to them. Each manufacturer comes up with their own specific way, usually based on TIFF but not always, to store the information of the image, thumbnail and metadata. We only partially understand how the formats work and what the fields mean and most of them use absolute offsets to specify things in the file (i.e., X bytes since the start of the file). If you edit a raw file (or convert it to DNG) some of these fields can become broken. Tools like exiftool try to make everything work by rewriting large parts of the file. In practice since the format is not fully known it is very likely you will be breaking something we currently don't care about but may in the future (e.g., where did the camera focus on) or even that you will be breaking something we care about already but are currently reading in one way and may read in another way in the future (we've had whitebalance break on the switch to rawspeed for example). If you care about your files working in the future just keep them exactly as the camera shot them. Don't edit any metadata, don't convert them to DNG. If you do any of these things you may not notice immediately but there's a big chance something in that file is now broken. Cheers, Pedro PS: I don't know if it's something in your email client but could you please get rid of those empty lines between each line of text? It makes it harder to read and to reply. ------------------------------------------------------------------------------ Go from Idea to Many App Stores Faster with Intel(R) XDK Give your users amazing mobile app experiences with Intel(R) XDK. Use one codebase in this all-in-one HTML5 development environment. Design, debug & build mobile apps & 2D/3D high-impact games for multiple OSs. http://pubads.g.doubleclick.net/gampad/clk?id=254741911&iu=/4140 _______________________________________________ Darktable-users mailing list Darktable-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/darktable-users
