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- Photography using Digital SLRs


Workflow Techniques #101

Workflow Buzzwords: Nondestructive, Non-modal, Selective, Layer/Operation-stacks

essay by Uwe Steinmueller


All these buzzwords are often used in current articles on imaging workflow. We try to explain them and show what is behind all the buzz. You will learn that these are very important properties for all imaging application but that it is not that easy to have it all.

Nondestructive Editing

The idea behind nondestructive editing that you start with your original image (RAW, JPG or scan) and only store the operations used to create your final image. This has a couple of main advantages:

  • You can change or fine tune any of the operations later and you don't need to redo the whole image from scratch
  • The instructions take way less disk space than the final rendered images
  • It is very easy to have different variations of operation sets

Almost all of today's RAW converters are based entirely on non-destructive editing. Photoshop's adjustment layers also implement a way to do non-destructive image operations. On the other end many of the more complex Photoshop operations are destructive.

Before you complain about the way Photoshop handles images you have to understand:

  • Photoshop allows way more complex operations than most other image editors
  • Photoshop provides some sophisticated selective editing capabilities (see below)
  • Photoshop was created at times where computer resources were way more limited than today
  • Photoshop was mainly designed for designers and not only for photographers (Adobe Lightroom is the application that is only targeted to photographers)


Selective Corrections

For more advanced imaging operations global image corrections just are not good enough. What you need is to have is selective operations. Selective operations are done via operation layers that can use masks (explicit or implicit like Nik's U-Point Technology).

Masks can be created the following ways:

  • Geometric shapes (with or without a feathering option)
  • Selecting color, brightness and saturation ranges
  • Painting techniques
  • U-Point technology which provides implicit masks based on color, brightness and saturation ranges

In the context of a non-destructive editing workflow you may also want to be able to edit the masks later.

Photoshop's layer masks allow the most sophisticated way to create selective image operations. Unfortunately the layer masks can easily become destructive themselves so that editing layer masks can be hard if even possible.

Nikon Capture NX features Nik's U-Point technology that allows powerful selective operations. Unfortunately the behavior of these corrections are more intuitive and hardly controlled in a more rigorous way.

LightZone provides geometrical shaped regions with feathering areas to enable selective editing. All regions can be re-edited at any time. Read our article on how to use these regions for a powerful dodge/burn workflow.

All other RAW converters that we know do not support any selective editing operations (Apple's aperture features some clone and healing tools that works selective though). We still hope that Adobe's Lightroom may also feature some selective tools as well.


Layer/Operation Stacks

Once an editor supports selective editing normally the operations get organized as layers or operation stacks (in the end kind of the same).

Layer stacks in Photoshop

Photoshop layer stack


Photoshop's power is only really used if you work with layers. Our books DOP2000 and DOP3001 teach how to use layers for photography. We could not live without them. Unfortunately many operations can easily become destructive and also the file size grows fast (especially with 16-bit images). Blending modes (define how the layer interacts with the base image) and opacity are a ways to even make layers more powerful.

Nikon NX operation stack

NX operations stack

Also Nikon Capture NX supports operation (layer) stacks. The masking is done via:

  • Implicit masks via U-Point technology
  • Geometric shapes with limited feathering capabilities
  • Painted masks

The operation layers also allow to change the opacity and support a limited set of blending modes.

LightZone operation stack

Lightzone operation stack

LightZone supports selective regions in a very systematic way and all tools implement them. Best you read both our LightZone review and our dodge/burn article.

Right now we miss selections via color and brightness ranges in LightZone. But we were told that this will be implemented in a future version of LightZone.


Non-Modal editing

What is a modal dialog? This is a dialog that opens and while it is open you cannot access any other operation inside a certain application.

  • The advantages of modal dialogs/operations is that they can be easily implemented (the software developer knows that his application does only one thing at that moment) and only uses screen space once while open.
  • The downside of modal dialogs is that switching operations is slow and tedious.

Good imaging requires non-modal dialogs for all the operations that are used most frequently because image editing is a highly iterative process. It is iterative because different imaging properties have influence on other properties of the image:

  • Contrast and brightness
  • White balance and colors

With selective imaging operations it can get even more iterative.


Most RAW converters work very much non-modal. But remember hardly any of them implements selective image corrections. This leaves mainly the following three applications:

  • Photoshop's adjustment layer operations are all modal
  • Capture NX also uses quite a few modal operation settings dialogs
  • LightZone is very much non-modal

LZ's non-modal controls

We hear that LightZone is slower than other editing applications but this is always based on wrong comparisons. Comparing a RAW converter that does not have selective correction is not fair as they solve a much more simple problem. Then if you compare LightZone to other editors that feature selective operations you will find that the practical use on LightZone is actually very fast and the use of non-modal editing operations is the secret. Overall we need less time in LightZone to do quite sophisticated corrections.

There is no doubt that Photoshop allows way more ways to correct images but you will find that the tools LightZone offers go a long way and the new LightZone RAW engine even makes it one of the top editors for nondestructive and selective RAW editing.


In the end we want it all:

  • Non-destructive
  • Non-Modal
  • Selective
  • Working with layer stacks

The design of such applications is by no means trivial and you hardly can have it all. Think that these applications need to reprocess the whole layer stack for every operation you perform (e.g. if you change a bottom layer).

LightZone is a major advance into the right direction. LightZone maybe not a replacement for Photoshop in all areas. Working with an application that allows non-modal editing gives you more freedom to experiment with your images.














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