Question

I am taking an imaging course (specifically medical imaging). Please provide the answer if you know it in terms of medical imaging or just digital imaging. I would greatly appreciate it :)

How can you find the spatial resolution of a photographic camera (mm or inch)?

Answer 1

Ans.)

When you hear the term ‘medical imaging’, the first picture that comes to mind is that of a radiograph, or an X-ray as it is more commonly known. While radiographs are the oldest and still the most frequently employed method of medical imaging, there is so much more to this intriguing and innovative field of science today. In this article, we attempt to review the current state of affairs and latest advancements in medical imaging technology as well as delineate areas where major breakthroughs are anticipated in the not-too-distant future.

The term ‘medical imaging technology’ has a broad definition and encompasses any technique that helps medical professionals view the interior of the body or areas that are not visible to the naked eye. Visualization of these structures can aid in the diagnosis of disease, treatment planning, treatment execution—such as through image-guided intervention, and monitoring and surveillance

The resolving power of a lens decreases as the aperture is decreased. Resolution decreases with increasing wavelength. It is about twice as great for extreme blue as per extreme red. The Rayleigh Criterion supplies the maximum theoretical resolving power in lines per millimeter. Resolving Power = 1392 ÷ f-number. The value 1392 is about the center of the photographic pictorial range of colors.

f/1.4 = 994 lines per mm

f/2 = 696 lines per mm

f/2.8 =487 lines per mm

f/4 = 348 lines per mm

f/5.6 = 249 lines per mm

f/8 = 174 lines per mm

f/11 = 127 lines per mm

f/16 = 87 lines per mm

This data is for on-axis objects, its worst for off-axis objects. This reduction in resolution as you stop down is due to the way light propagates. We are taking about the combined nemeses of diffraction and interference. Note that the resolution at f/8 exceeds most pictorial film ability.

To calculate the total resolution of a system, we test with parallel ruled test charts and insect to see how many lines per millimeter can actually be resolved. This will be a variable based on subject contrast and camera exposure and how well the lens is corrected for aberrations.