1、 WHITE PAPER WHITE PAPER High Dynamic Range Imaging for Machine Vision PAGE 1 WHITE PAPER High Dynamic Range Imaging for Machine Vision Cover image:Example of dual-gain HDR image fusion(see page 15).What is dynamic range?Dynamic Range is the term used to describe the difference between the brightest

2、 part of a scene and the darkest part of a scene at a given moment in time in other words,the amount of contrast within a single image.Dynamic range is typically measured in bits or dB.For example,a scene where the brightest point is roughly 1000 times brighter than the darkest part of the scene wou

3、ld be said to have approximately 10-bits of dynamic range or 60 dB.Note that this instantaneous measurement of contrast is different than brightness that changes over time,which can typically be handled by some sort of auto-exposure capability.An evenly-lit scene with no shiny objects or light sourc

4、es in the field of view would be considered to have low dynamic range.In such a scene,the brightest point would generally be less than 255 times brighter than the darkest part of the scene,thus enabling all parts of the scene to be accurately represented in an 8-bit digital image.Cameras with up to

5、12-bit imaging capabilities are common in the machine vision world,enabling scenes to be captured with dynamic ranges approaching 72 dB(4096:1).How is Dynamic Range Handled by a Digital Camera?The pixel values associated with a digital image are determined by the amount of light(photons)that strikes

6、 each physical pixel on the cameras imager during the exposure period.Photons can come from light that is reflected off objects in the scene(reflected light)or can come directly from light sources that are within the cameras field of view(emitted light).The photons cause the pixel well to fill with