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  2. Image subtraction - Wikipedia

    en.wikipedia.org/wiki/Image_subtraction

    Image subtraction or pixel subtraction or difference imaging is an image processing technique whereby the digital numeric value of one pixel or whole image is subtracted from another image, and a new image generated from the result.

  3. Optical resolution - Wikipedia

    en.wikipedia.org/wiki/Optical_resolution

    Two adjacent points in the object give rise to two diffraction patterns. If the angular separation of the two points is significantly less than the Airy disk angular radius, then the two points cannot be resolved in the image, but if their angular separation is much greater than this, distinct images of the two points are formed and they can ...

  4. Relative change - Wikipedia

    en.wikipedia.org/wiki/Relative_change

    A percentage change is a way to express a change in a variable. It represents the relative change between the old value and the new one. [6]For example, if a house is worth $100,000 today and the year after its value goes up to $110,000, the percentage change of its value can be expressed as = = %.

  5. Similarity measure - Wikipedia

    en.wikipedia.org/wiki/Similarity_measure

    Similarity between two data points. Image shows the path of calculation when using the Euclidean distance formula. There are many various options available when it comes to finding similarity between two data points, some of which are a combination of other similarity methods.

  6. Angular resolution - Wikipedia

    en.wikipedia.org/wiki/Angular_resolution

    A calculation using Airy discs as point spread function shows that at Dawes' limit there is a 5% dip between the two maxima, whereas at Rayleigh's criterion there is a 26.3% dip. [3] Modern image processing techniques including deconvolution of the point spread function allow resolution of binaries with even less angular separation.

  7. Full width at half maximum - Wikipedia

    en.wikipedia.org/wiki/Full_width_at_half_maximum

    In a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value. In other words, it is the width of a spectrum curve measured between those points on the y -axis which are half the maximum amplitude.

  8. Arc elasticity - Wikipedia

    en.wikipedia.org/wiki/Arc_elasticity

    The y arc elasticity of x is defined as: , = % % where the percentage change in going from point 1 to point 2 is usually calculated relative to the midpoint: % = (+) /; % = (+) /. The use of the midpoint arc elasticity formula (with the midpoint used for the base of the change, rather than the initial point (x 1, y 1) which is used in almost all other contexts for calculating percentages) was ...

  9. Numerical differentiation - Wikipedia

    en.wikipedia.org/wiki/Numerical_differentiation

    The simplest method is to use finite difference approximations. A simple two-point estimation is to compute the slope of a nearby secant line through the points (x, f(x)) and (x + h, f(x + h)). [1] Choosing a small number h, h represents a small change in x, and it can be either positive or negative.