How does image digitalization differ from sound digitalization (PCM)?
I am trying to understand digitalization of sound and images. As far as I know, they both need to convert analog signal to digital signal. Both should be using sampling and quantization.
Sound: We have amplitudes on axis y and time on axis x. What is on axis x and y during image digitalization?
What is kind of standard of sample rate for image digitalization? It is used 44kHz for CDs (sound digitalization). How exactly is used sample rate for images?
Quantization: Sound - we use bit-depth - which means levels of amplitude - Image: using bit-depth also, but it means how many intesities are we able to recognize? (is it true?)
What are other differences between sound and image digitalization?
Acquisition of images can be summarized as a spatial sampling and conversion/quantization steps. The spatial sampling on (x,y) is due to the pixel size. The data (on the third axis, z) is the number of electrons generated by photoelectric effect on the chip. These electrons are converted to ADU (analog digital unit) and then to bits. What is quantized is the light intensity in level of greys, for example data on 8 bits would give 2^8 = 256 levels of gray.
An image loses information both due to the spatial sampling (resolution) and the intensity quantization (levels of gray).
Unless you are talking about videos, images won't have sampling in units of Hz (1/time) but in 1/distance. What is important is to verify the Shannon-Nyquist theorem to avoid aliasing. The spatial frequencies you are able to get depend directly on the optical design. The pixel size must be chosen respectively to this design to avoid aliasing.
EDIT: On the example below I plotted a sine function (white/black stripes). On the left part the signal is correctly sampled, on the right it is undersampled by a factor of 4. It is the same signal, but due to bigger pixels (smaller sampling) you get aliasing of your data. Here the stripes are horizontal, but you also have the same effect for vertical ones.
- Math.Sin() gives incorrect value
- How to run my python script when the sunOS is start booting
- Express-session: not resetting cookie expiration on each request
- Getting a stack overflow exception when normalizing a vector
- Edit default summary function in R gives error for multiple variables
- What was a For loop? Why isn't it needed in R?
- How to use download button in shiny and save results in various formats (csv, texte, pdf, spss...)?
- Why are there two assignment operators, `<-` and `->` in R?
- lm()$assign: what is it?
- How to get the value of list(...) in R and S functions
- Design matrix for MLM from library(lme4) with fixed and random effects
- how to generate elements not included in my sample
- Create a matrix with gradually changing values without a for loop
- Emacs ESS and S-plus ( S+ ) 8.1 compatability
- How to lag date-index in a time-series in R?
- Nonlinear regression in R / S
- Calling R from S-Plus?