A reader sent me a message this morning saying that he is confused by all the acronyms associated with the current set of posts, and asked me to post a glossary that he could keep open as he read the others.
Here goes:
ADC – analog to digital converter
CFA – color filter array
CSV – comma-separated vlaues
dB – decibel; one-tenth of a Bell.
DC – direct current; the zero frequency component in the frequency domain
DN – you won’t see that acronym here; I find it awkward and tautological. I use count or LSB instead, depending on the context
F – spatial frequency
Fs – spatial sampling frequency
FWC – full-well capacity
ISO – I don’t think this actually stands for anything anymore; Possibly it used to, in some language-dependent way, stand for the International Organization for Standardization. Maybe someone can straighten me out. When used to identify film speed, it meant the same thing as ASA, which did indeed stand for the American Standards Organization.
LSB – least significant bit
Mu – mean, or average value
PRNU – photo response nonuniformity
Post-amp RN – read noise that occurs after the camera gain stage
Pre-amp RN – read noise that occurs before the camera gain stage
RN – read noise
ROI – region of interest
Sigma – standard deviation; the square root of the variance
SNR – Signal to noise ratio
TIFF – tagged image file format
Chris Livsey says
You will love this: The ISO standard ISO 12232:2006 allows, as one of a choice of techniques, the maker of a digital camera to specify EI arbitrarily !!
The choices are the manufacturer’s opinion of what EI values produce well-exposed sRGB images at the various sensor sensitivity settings.
What’s that about “not worth the paper it’s written on” ?
Abe says
Typo: PNRU -> PRNU
ISO is only an output format “standard”, and has nothing whatsoever to do with raw files or image sensors. And Chris commented, the standard allows arbitrary definition of ISO 🙂
You forgot ADU – if you don’t like DN, then maybe “analog digital unit” or “arbitrary digital unit” doesn’t sound good either 😉
(I do wish you’d use DN as it’s common terminology in this field…)
Jim says
Abe,
PRNU: fixed, thank you.
ISO does have something to do with raw files, as it is the name of the control that changes (or doesn’t, sometimes) the gain applied to those files. Aside from that, I agree with you.
Yep, you’re right; I dislike ADU every bit as much as DN. I’ve worked with digital sampled date systems since 1969. Until I encountered the, IMHO, awkward terminology of sensor analysis, every time an engineer wanted to talk about he raw number coming out of an ADC, he (and, it almost always was a he, in the thirty years that I worked in those fields) say “the count”. There was never any ambiguity or confusion among the listeners. It was simple. It was direct.
About the common terminology: maybe I’ll come around after I hear “data number” over and over again until I’m completely worn down, but it just grates on me so much now I can’t bear to use the term. Maybe it could be made even more tautological, then just plain DN would look good by comparison. How about “Quantized Digital Representation of Some Physical Phenomenon/Parameter WithOut Reference to Offset or Scale”? QDRSPPWOROS, for short.
Jim