A Guest post by Dave Ware from Whalebone Photography.
This note is aimed to be a quick discussion on High Dynamic Range and possible future enhancements to improve it.
What is High Dynamic Range?
High Dynamic Range is a digital processing effect used within photography to combine a number of images of differing exposures to create a consistently exposed picture throughout the entire frame. This increases the luminance (amount of light) visible within an image.
Why is it required?
The camera’s limitation of amount of colour and luminance it can record is governed by the sensor’s capability and the dynamic range of the camera’s electronics. For example, the Canon EOS 40D uses a 14 bit analogue to digital converter which digitises the analogue signals received from the sensor. The 14 digital bits allow 16,384 different colours to be recorded within the camera.
Looking a a histogram, the horizontal axis is the level of luminance of an image. The vertical axis represents the amount of the image which contains that level of light. For example, a histogram with a single line at the left hand edge shows that the image is purely black. Likewise, a single line at the right hand edge represents an image which is purely white. The amount of data which may be compressed within the histogram is limited by the dynamic range of the camera. A very low dynamic range results in the horizontal axis limits close together. A high dynamic range places these axis far apart.



A Guest Post by Josh Brown from


