Summary and lessons:
· Dynamic range is sometimes referred to as contrast ratio. I found it helpful to think about it as a ratio between the darkest and the lightest areas of an image. Where dynamic range of a scene is
concerned, digital cameras have limitations. A human eye is capable of seeing a much higher dynamic range in comparison to a digital camera.
concerned, digital cameras have limitations. A human eye is capable of seeing a much higher dynamic range in comparison to a digital camera.
· Incident and reflected light: This exercise demonstrated that incident and reflected light may affect the dynamic range of a scene. For example, strong reflections and uneven incident light increase dynamic range of the scene.
· Link to exercise on ‘Tolerance for noise’: There is a link between ISO settings and the way a camera is able to record the dynamic range of a scene. This exercise demonstrated that lower ISO settings tend to increase dynamic range.
· Link to exercise on ‘Sensor linear capture and Gamma corrections’: Dynamic range may be affected by the gamma correction applied by the camera or post-capture image processing software. Gamma corrections need to be taken into consideration, particularly when recording a scene with a wide dynamic range.
· Using image magnification (1:1 or higher) is helpful as it allows to observe any changes in image quality and to assess the levels of noise in the image associated with recoding a scene with a wide dynamic range.
· It does not always necessary to record the entire dynamic range of a scene. Sometimes, for artistic purposes and special effects the dynamic range of a scene might be reduced.
· Decreasing the levels of dynamic range of a scene
o This exercise helped me to consolidate and systematise all my previous experience on dealing with the high dynamic range of a scene:
o Adjustments can be made at different stages of the image capture and processing to help record a wider dynamic range of a scene.
o The simplest method on location is to look for a different angle or camera position. There are tools and techniques that help to make a better use of the available dynamic range values. For example, graduated neutral density filters can be used with digital or film cameras to record a wider range of values. The principle used in this instance is based on regulating exposure of different areas of the image. Dodging and burning tools in both darkroom and digital image processing usually aim to achieve a similar purpose.
o There are also techniques that are based on extending the dynamic range of luminance of an image. These techniques are usually referred to as HDRI or high dynamic range imaging and include:
- Computer rendering, and
- Creating an image from merging a series of photographs with various exposure values, this process sometimes referred to as ‘sandwiching’.
Tone mapping techniques are sometimes used for special effects.
