- Oct 20, 2006
- Reaction score
- Oct 20, 2006
The difference is I clearly was referring to audio processors, and you conflated my short statement with file bit depth. Light is not the same form of energy as electricity. The point was that although not the same, there is still a conversion to electric signal and an analog to digital conversion happening in digital photography. And again, modern images are thought of in bits per channel: not total bits of image (for example, there are images that are a total of 32bit with 8bpc RGB and alpha transparency). And I can leave it at that.1. I don't necessarily assume other people are ignorant of the facts! If someone makes some assertion that is incorrect, I assume that EITHER they're ignorant of the facts, that they're not ignorant of the facts but don't really understand them or that they're not ignorant of the facts, do understand them but are erroneously dismissing them for some reason. What rational alternative am I missing?
1a. I didn't state your post didn't have some clarity and I didn't dispute this assertion, only some specific facts within your assertion, your analogy with digital imaging and your conclusion/assertion of there being "no final answer".
2. More than a few I should imagine!
3. But I didn't say that! What I effectively (tried to) say is that to begin with we do NOT even have audio, we have sound pressure waves that needs to be transduced into audio and only then can it be converted to digital. Therefore:
3a. "No", because photography does not have to be transduced as well. Both digital audio and (as I understand it) digital imaging involve an analogue stage and then an ADC but a major difference is that digital imagining involves converting between different types of the same form of energy (light and electricity which are both electromagnetic energy), while digital audio recording involves converting between two different forms of energy (mechanical and electromagnetic).
3b. No, a photodiode is very significantly different to a microphone. As far as I'm aware, photodiodes are microscopic devices with no moving parts (solid state) which operate at the quantum level converting a photon/s into an electron/s. Microphones do NOT conduct electricity based on the intensity of sound, they generate electricity based on the "intensity" of movement of a diaphragm. A microphone therefore has to first convert variations in sound pressure into the mechanical motion of a diaphragm and then convert that mechanical motion of the diaphragm into electricity. So, we're dealing with relatively huge mechanical devices, subject to all the limitations of the laws of physical motion/transduction, all of which results in relatively massive inefficiency (compared to image sensors) in the generated analogue signal, which then of course is the input for conversion to digital data. In the practical application of digital audio, it's this inefficiency which defines system limitations, not the ADC, DAC or number of bits (beyond 16). A somewhat better analogy with an image sensor would have been a tape recorder, which also converts between different types of the same form of energy (electrical and magnetic) but it's still a rather poor analogy as tape recorder performance is still reliant on mechanical forces (physical properties of the tape itself, plus friction, tape alignment, motor/speed, etc.).
4. Another significant difference! Over the years, digital audio has changed significantly but the resultant output resolution and dynamic range has barely changed at all. Even in the earliest days of consumer digital audio (CD) the hardware was capable of 16 bits, near perfect resolution and a dynamic range in excess of both the limitations imposed in practice by microphones or that would be experienced in the real world (at a gig).
5. And another reason to be wary of comparing digital imaging with digital audio, that I've already mentioned. With digital imaging,16 million colours (24bit) still does not cover all the capabilities of the human eye. If, as you say, it only provides 8 stops and the human eye is capable of 20 stops, then it's still a long way from the capabilities of the human eye. For the human ear though, 16bit is already beyond it's capabilities and a long way beyond "comfortable".