Max theoretical resolution of scanned images.

In summary, the maximum possible resolution of a scanned A4 image would be 1.56 terapixels, assuming the use of violet light for greyscale and red light for color images. However, this is based on the assumption that the image being scanned is of that high resolution. Visible light has a wavelength of 400-700nm and there are microscopy techniques that can detect positions smaller than the wavelength. Some non-light microscopes can also resolve individual atoms. The max resolution of a simple optical scanner is half the wavelength, giving a maximum resolution of 200nm and an average of 275nm. The useful resolution for a graphite drawing is likely limited to the size of the canvas or paper pulp particles. The diffraction limit
  • #1
Energize
30
0
May seem like a bizarre question but I was wondering what the maximum possible resolution of a scanned A4 image would be.

A4 paper is 0.297m x 0.21m, average resolution of light is 200nm.

So I get,

(0.297m / 200x10^-9m) x (0.21m / 200x10^-9m) = 1.56 terapixels

Is this about right? Would we be able to use violet light for a greyscale image to achieve a higher resolution, and would we have to stick to the resolution of red light to get an accurate scan with a colour image?
 
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  • #2
Energize said:
average resolution of light is 200nm.
Visible light has a wavelength of around 400 to 700nm
There are microscopy techniques that will give you position of an edge that is smaller than wavelength and you can detect the position of small high contrast objects that are smaller than a wavelength

And of course some non-light microscopes can resolve individual atoms
 
  • #3
This all assumes that the image being scanned is that high of a resolution.
 
  • #4
mgb_phys said:
Visible light has a wavelength of around 400 to 700nm
There are microscopy techniques that will give you position of an edge that is smaller than wavelength and you can detect the position of small high contrast objects that are smaller than a wavelength

And of course some non-light microscopes can resolve individual atoms

The max resolution of a simple optical scanner is half the wavelength though is it not? Giving a max resolution of 200nm and average of 275nm?

russ_watters said:
This all assumes that the image being scanned is that high of a resolution.

How does one determine the max resolution of say a graphite drawing, I assume it is related the size of the graphite molecules?
 
  • #5
Energize said:
How does one determine the max resolution of say a graphite drawing, I assume it is related the size of the graphite molecules?
I'm not sure you can really say a graphite drawing is an "image" - it is more of a physical object.

The useful resolution is probably limited to the size of the fabric of the canvas or paper pulp particles.
 
  • #6
Energize said:
The max resolution of a simple optical scanner is half the wavelength though is it not? Giving a max resolution of 200nm and average of 275nm?
The diffraction limit of a NA [tex]\approx[/tex] 1 objective is about 0.5wavelengths
But this is a very simplistic picture of resolution
 

1. What is the definition of "max theoretical resolution"?

The max theoretical resolution of a scanned image refers to the highest possible level of detail that can be achieved when scanning a physical image or document. It is typically measured in dots per inch (dpi) or pixels per inch (ppi).

2. How is the max theoretical resolution determined?

The max theoretical resolution is determined by the capabilities of the scanning device, such as the optical resolution of the scanner, the size of the pixels in the image sensor, and the quality of the lens. It can also be affected by the size and quality of the original image being scanned.

3. Is the max theoretical resolution always achievable in practice?

No, the max theoretical resolution is not always achievable in practice. Factors such as image distortion, noise, and limitations of the scanning software can affect the final resolution of the scanned image. In addition, the quality of the original image being scanned may also impact the achievable resolution.

4. How does the max theoretical resolution differ from the actual resolution of a scanned image?

The max theoretical resolution is the highest possible level of detail that can be achieved, while the actual resolution is the level of detail that is actually captured in the scanned image. The actual resolution may be lower due to limitations of the scanning device or image quality, as well as any post-processing that may be applied to the scanned image.

5. Can the max theoretical resolution be improved?

Yes, the max theoretical resolution can be improved by using a higher quality scanning device or by improving the quality of the original image being scanned. In addition, post-processing techniques such as interpolation can be used to enhance the resolution of the scanned image.

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