To create a digital image, we need to convert the continuous sensed data into digital form.
This process includes 2 processes:
- Sampling: Digitizing the co-ordinate value is called sampling.
- Quantization: Digitizing the amplitude value is called quantization.
To convert a continuous image f(x, y) into digital form, we have to sample the function in both co-ordinates and amplitude.
Difference between Image Sampling and Quantization:
|Digitization of co-ordinate values.||Digitization of amplitude values.|
|x-axis(time) – discretized.||x-axis(time) – continuous.|
|y-axis(amplitude) – continuous.||y-axis(amplitude) – discretized.|
|Sampling is done prior to the quantization process.||Quantizatin is done after the sampling process.|
|It determines the spatial resolution of the digitized images.||It determines the number of grey levels in the digitized images.|
|It reduces c.c. to a series of tent poles over a time.||It reduces c.c. to a continuous series of stair steps.|
|A single amplitude value is selected from different values of the time interval to represent it.||Values representing the time intervals are rounded off to create a defined set of possible amplitude values.|