100 Days of Photo Editing by Digital Compositing on iPhone

This is a 100 days series that explores the use of Digital Compositing for Photo Editing and Photo Post-Processing.

Why bother?

When using software for photo or image post-processing, tools such as Photoshop or LightRoom immediately comes into mind. These are indeed useful tools that many professionals are familiar with. There are also many tutorials, articles, and videos, available on the internet, that discuss how to perform the different image editing tasks. Why then do we bother to use a different concept, Digital Compositing, for a discussion on Photo Editing?

The short answer to this:

“The ability to express what we want to do Succinctly”

The above statement has a significant impact on the design on graphical or image post-processing software.

Background

Many popular image post-processing tools uses the concept of Layering for performing image editing tasks. Different layers are used to separate the different elements of an image with each element placed over or under to create a final desired output. On the other end of the spectrum, it is interesting to note, that in movie post-production, there are two classed of programs: those that are Node based (Digital Compositing) and those that are Layer based.

There are many comparisons being made between these two classed of programs. From a research paper here , at Video Maker , and by The Inside Tips .

In the next 100 articles (days), I hope to discuss on various topics of image post-processing. And in the process, hope to present an alternative, the use of Digital Compositing, for photo editing, filters, effects, animation, and eventually Augmented Reality.

Digital Compositing

Digital Compositing (node-based) is the process of combining multiple seemingly simple nodes to render and achieve a desired result. The paradigm of a node-based tool involves linking basic media objects onto a procedural map or node graph and then intuitively laying out each of the steps in a sequential progression of inputs and outputs. Any parameters from an earlier step can be modified to change the outcome, with the results instantly being visible to you, and each of the nodes, being procedural, can be easily reused, saving time and effort. 


                Read photo
                |
                V
                Photo Curve (or Tone Curve)
                |
                V
                Retouch
                |
                V
                Gaussian Blur
                |
                V
                Viewer

To expand it further, if we need to merge images to achieve a particular effect, we can express it in a node graph as below: 


                 Read photo  Read photo
                 |           |
                 V           V
                 Exposure    Color Correction
                 |           |
                 |           V
                 |           Retouch
                 |           |
                 |           V
                 |           Gaussian Blur
                 |           |
                 V           V
                     Merge
                       |
                       V
                     Viewer

Digital Compositing Pipeline

A node graph can be expressed easily graphically. This presents a difficulty, the steps will need to be drawn out in a node graph, in expressing on how we can achieve something. The interesting thing about node graph is it can be expressed as a list of steps in English succinctly. For example, the node graph above can be expressed as a list of steps below: 

       
                1. Read photo
                2. Exposure         (1)

                3. Read photo
                4. Color Correction (3)
                5. Retouch          (4)
                6. Gaussian Blur    (5)

                7. Merge            (2,6)
                8. Viewer           (7)
                Note - The brackets e.g. "(1)" refers to the input node or image.

A list of steps is both easy to create and easy to understand. It is also a succinct medium that we can conveniently type into a document or used it for discussion in a book. It can also be displayed easily on a device with a limited screen space such a mobile phone.

Find out more

Nodef Pipeline

ShaderMuse