Sampling

How does digital sampling affect resolution

Look at imaging these object with a digital camera

How close together do pixels need to be?

Sampling over time:

How often do you need to image a moving sample

 

Nyquist theory states that you should sample more than 2 X the frequency that you expect.

Over sampling

Nyquist sampling

Under sampling causes aliasing

Optical Transfer Function MTF

 

 

 

 

When objects get close together the contrast decreases.

MTF = Image Modulation/Object Modulation

MTF = 2(φ - cosφsinφ)/π   and  

                  φ = cos^-1(λν/2NA)

 

The Optical Transfer function is the Modulation transfer function times a phase component.

OTF = MTF × eiφ(f)

 

 

 

Camera bit depth

   0 or 1

00 or 01 or 10 or 11

000 or 001 or 010 or 011 or 100 or 101 or 110 or 111

and so on

    

Jpg is 8 bit Tiff can be 16 bit

 

references

https://imb.uq.edu.au/research/facilities/microscopy/training-manuals/microscopy-online-resources/image-capture/nyquist-conditions

https://microscopy.berkeley.edu/courses/dib/sections/02images/sampling.html

https://ocw.mit.edu/courses/mechanical-engineering/2-71-optics-spring-2009/video-lectures/lecture-22-coherent-and-incoherent-imaging/MIT2_71S09_lec22.pdf