HDR stands for High Dynamic Range image
A ‘HDR’ image, as taken by the Spheron system contains 32-bits of information, offering an almost limitless data range for color and luminance (brightness).
To explain what 32-bit means in relation to an image, lets start with a 1-bit image.
‘1’ bit would equal 2 to the power of 1 = 2 or 2 x 1 = 2
This would allow 2 tones – eg Black or White
‘4’ bit would equal 2 to the power of 4 = 16 or 2 x 2 x 2 x 2
This would allow 16 tones
- 1 bit = 2 levels (black and white)
- 4 bit = 16 colors / greyscale tones
- 8 bit = 256 colors / greyscale tones
- 16 bit = 65536 colors / greyscale tones
- 32 bit = approx. 4.3 Billion color / greyscale tones
For reference, the human eye is perceived to register about 10 million colors.
HDR images are used for two main applications
- Photography – to provide extra color / luminance range in the image*
- CGI Rendering (Computer Rendering) via a process called Image Based Lighting (IBL)
* In reality, to actually appreciate this information as a print or via screen, the image is often ‘tone-mapped’
To understand how the Spheron system captures a HDR image, read more here: