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Non destructive editing is a postprocessing strategy which records the operations performed on the image, and shows their result, rather than altering and saving the pixels themselves. Some applications, such Nikon Capture ad Adobe Lightroom edit non-destructively as a matter of course. In other applications, such as Photoshop, layers can be used to enable non-destructive editing. The software Annotate by Nikonians is used for creating comments (annotations) that are bound to coordinates in an image (e.g. people tagging). This is done in a non-destructive way in the image.
Non-destructive editing differs strongly from undoable editing in that, when a file is saved, only the final version is saved. For a non-destructively edited file, although the preview may be substantially different, the underlying pixels remain the same. For a file edited in an application such as Photoshop which allows a history of undos, the changed pixels are saved, and the undo history is lost once the file is closed.
- Raw files, including NEF and DNG can only be edited non-destructively.
- TIFF and PSD files can be saved with several layers, so the non-destructive edits can be preserved if they have been done using layers. However, this may result in a vastly increased file size.
- JPEG files only record the single, final image.
Although it is in principal advantageous to edit non-destructively where possible, only certain classes of edits can be applied. These are adaptive edits and global edits, such as unsharp masking, levels, hue, saturation, and noise reduction. Nikon's U-point technology and Adobe Lightroom's adjustment brush effectively simulate local changes for spot removal and some other classes of change. However, deconvolution filters such as FocusMagic, advanced noise reduction algorithms such as NoiseNinja and extensive treatments such as those provided by Imagenomic Portraiture and Tiffen dFx are only effective destructively. By retaining a background layer in Photoshop it is possible to retain the original image. However, in this case, there is no difference between doing this and simply retaining a backup copy of the original image, and there is no advantage in file size.
- This page was last modified on 30 November 2009, at 15:55.
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