Within some RAW developing applications, Aperture, Lightroom, ACR, you can tweak these values visually, you can push the black point up to see more details sometimes. If we kept black as 0 this noise could create negative black values - and so part of the linearastion process makes anything below the black level remap to 0. Usually cameras don’t output 0 for black, the value is raised to allow us to keep the sensor noise. Apply the white and black point and scale to fit into 16 bit. Is the source camera data stored inside the DNG actually linear as well? If so then the process is very simple. This linerasation step depends on a number of factors. Camera sensors are generally linear in their nature except for the extremes (shadows and highlights). Linear, or more accurately 'Scene Linear', means a doubling of value is a doubling of light. The ultimate output from a DNG is a linear image from which the application can further alter. A linear image is a very simple but accurate representation of the real world light values in a scene. The first step is linerisation of the data held in the file.

Lets look at how a DNG file is 'developed' into a ‘real world’ image The next blog post will deal with Linear Light and why it's so important when grading or using VFX Developing a DNG There are myriad of excellent resources around to go into the details of debayering so there’s no point doing that here. Below that is the kind of image that comes from the data, it's linear data which means that it's very dark save for the highlights (you can just about see the edge of the aerial) - more on this later. You can see it is basically a grey scale image from the sensor. The image to the left shows a prebayered image, with the bayer patterning still intact. The key to a DNG is it is self describing. This data includes details about colour matrixes, white balance, black and white points and information needed to recreate what the camera saw. The DNG file also contains meta data about the image and the camera. Some applications don’t give you any choices, and they have their own proprietary debayer approach.

The image here shows the differences between some common algorithms. cDNG is cinema DNG which is a superset of the DNG standard and it’s becoming more common with support increasing all the time - although when it comes to valid workflows it’s the wild-west out there.Įach DNG contains the data from the camera before debayering (hence RAW data), this means that each application supporting DNG can offer a myriad of different ways to debayer (or ‘develop’) this data - each route can produce a different image. Both the 2K and 4K RAW but should apply to other cameras. This post is specifically focused on the RAW data from the FS700 via the Odyssey 7Q. DNG, a digital negative, was designed to hold the RAW sensor data from your camera.

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