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RAW Files Destructive editing

Discussion in 'Digital Image Editing & Printing' started by Charles2016, Aug 24, 2018.

  1. Charles2016

    Charles2016 Member

    Hi guys,

    I have a feeling I'm missing something here.

    I'm from an electronics / computer background and the idea of taking any file from any electronic system and editing it without keeping a copy of the original is unheard of, in fact it would be the height of incompetence. So why does this seem to be an issue with photo editing software? I can manually save and copy the RAW files from my camera to any number of folders on my PC or in the cloud, so why is "destructive" editing even a talking point? As I say I might be missing something.


  2. Roger Hicks

    Roger Hicks Well-Known Member

    Who DOESN'T keep RAW files (if they bother to shoot them)? And why not?


  3. Andrew Flannigan

    Andrew Flannigan Well-Known Member

    It wasn't always that way. To those of us who started coding when 8K was a good sized memory and a 500K 8" floppy was as much as most machines offered this sort of trade off was business as usual. When the first editors were released in the 1990s memory was still relatively expensive as was disk space while image files were big. It probably seemed like a good idea to trash the work files when the session was saved to avoid crashing the program and possibly taking the file system with it.

    Of course these days it's a stupid way to proceed but as Roger points out: why wouldn't you back up up the original files long before you opened them in the first place?
  4. RogerMac

    RogerMac Well-Known Member

    AND store the originals in either a separate location or a fire proof safe
  5. PeteRob

    PeteRob Well-Known Member

    I don't know of any raw processing software that is destructive. The software saves the image processing instructions separately to the image data, either in a database or as an associated file (sometimes called a sidecar file). When you re-open the file in the processor it loads the original data and then the processing instructions. Canon's own DPP does save the instructions inside the raw file itself but entirely separate to the image data*. The advantage of raw processing is that you can modify the processing instructions many times. Some packages let you save several different processing sets for the one original image data set.

    Programs that edit jpgs are inherently "destructive" because the format uses compression when the file is saved. Also many packages default to save to the original file name and location making it easy to overwrite the original. They often also have the option to work in uncompressed format (e.g. TIFF) but the danger of overwriting by accident remains. If working with jpgs do not make multiple edits (file save/opens) and always use the highest quality to avoid data loss.

    It is always sensible to preserve backup copies of original data as a guard against loss. This is nothing to do with photography per se, it is just sensible data protection. Of my photographs I have 3 copies at any one time, both of the image data and of the processing instructions (through the Adobe Lightroom catalogue). These are 1 working version and 2 backups all on different media.

    *you can edit the same file in DPP and in LR. DPP will only see the DPP instructions and LR will only see the LR instructions. I'm also playing with On1 as a potential replacement for LR 6.14 (which is no longer supported) and On1 is supposed to be able to read LR instructions and apply them if they are optionally exported to a sidecar file. I haven't tested how portable this really is. On1 also has its own separate catalogue so again On1 edits can be saved independently from the same file.
  6. Chester AP

    Chester AP Well-Known Member

    As an ex-IT person who asked myself the same question 10 years ago, I think the best way to compare a processed RAW file with an 'ordinary' computer data file is to think of it as an unchanged original plus additional data that will be used to manipulate it next time it is opened. It is this 'additional data' that you change when you edit the RAW file.

    Possibly what you mean is, having processed a RAW file and saved the changes (ie. created or updated the 'additional data' that processes the file when next opened), what if you want to scrap all the changes and start again and have the RAW file displayed as it was before it was processed? The RAW software I use does not allow this, but other software might. If this is what you mean, all you have to do is copy the RAW file to a new name (add 'original' to the name?) before working on it, so that it is always available if you want to start again. Disc space is so cheap today that having copies of some RAW files isn't going to be a problem.
  7. Charles2016

    Charles2016 Member

    Hi Chester, this is exactly what I meant and your solution is what I thought was the answer! So nice to receive some confirmation, thanks.

  8. PeteRob

    PeteRob Well-Known Member

    LR and on1 allow "virtual copies" so can keep as many development options as you like. You don't need more than one version of the raw-file. I expect Capture
    one does too. Canon DPP doesn't as far as I am aware. You can always reset to the beginning.

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