Resolution

The resolving power, fineness of detail that is clearly reproduced in an image. ¹

1. In a practical sense, resolution is usually judged by imaging test targets bearing sets of spaced black and white lines in a square-wave pattern, and determining the minimum spacing for which the lines are distinguishable in the resultant image. [Practitioners explain: ‘If I can agree that lines are distinguishable as lines, and if they correspond in number and arrangement with the target, they are resolved.]

2. With instrumentation readout, resolution target charts are less ambiguous and more useful if they bear sets of spaced ‘black’ and ‘white’ lines sinewave modulated in density, rather than square-wave modulated.

3. Whereas square-wave targets introduce a Fourier series of higher frequencies, sinewave targets limit the analysis to a single frequency for each line set. Quantitative measurement of the modulations provides convenient determination of the transfer function.