Skip to main content

Sampleling

How does digital sampling affect resolution

Look at imaging these object with a digital camera

 

image-1637163325668.jpg

How close together do pixels need to be?

or

image-1637163343425.jpg

how often do you need to image a moving sample

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

Over sampling

image-1637166398425.jpg

Nyquist sampling

image-1637166436296.jpg

under sampling causes aliasing

image-1637166449555.jpg

Optical Transfer Function MTF

 

image-1637271420704.jpg  image-1637272536733.png

 

 

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 ratio of the intensity of the image over the intensity of the sample.

OTF = MTF × eiφ(f)

were

MTF = Image Modulation/Object Modulation

MTF = 2(φ - cosφsinφ)/π   and  

 

φ = cos-1(λν/2NA)

 

IntensityCamera levelbit depth

 

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

 

Back to top