![]() What kinds of pictures? That’s the cool thing! You can make connect-the-dots pictures of just about anything! When someone draws lines to connect the dots in the right order, it creates a picture. Have you ever done a connect-the-dots puzzle? If so, you know they contain a sequence of numbers or letters. These puzzles are also known commonly as dot-to-dot or join-the-dots puzzles. What are we talking about? Connect-the-dots puzzles, of course! Educators have used them for ages to help teach kids numbers or letters. Some use similar puzzles to learn the alphabet, too. Notes: the third order calculations (Distortion and SFRplus) are less accurate than the fifth order and arctan/tan calculations (i.e., they cannot be as good a fit to the actual distortion.) The green line (SMIA TV Distortion) in the Dot Pattern figure cannot be compared with the other figures.How did you learn to count? Do you remember back that far? Many kids use a special kind of puzzle to help them learn numbers. ![]() The Dot Pattern module uses the algorithm specified in the Camera Phone Image Quality (CPIQ) specification, but the other modules produce equivalent results. ![]() As the Lens Geometrical Distortion figures for the three modules show, agreement is excellent. ![]() The zip file includes barrel and pincushion-distorted images for Distortion, Dot Pattern, SFRplus, and eSFR ISO. These images were created by the Test Charts module, converted to bitmaps of the same size (if needed), then equally distorted. Comparison with Distortion and SFRplus modulesĪ set of images for comparing different Imatestdistortion calculations can be downloaded by clicking on distortion_comparison_barrel_pin.zip. By summarizing the SMIA TV distortion as a function of image radius (rather than a single number) we gain a better understanding of the distortion aberration. Ordinarily the SMIA TV distortion metric is taken to be a single number the value of the green curve at the far-right of the plot. The SMIA TV distortion is plotted as the green curve. As a measure of the quality of the polynomial fit the figure provides the mean error and standard deviation between the measured data and the polynomial fit. ![]() A polynomial model is fit to the measured optical distortion data (using a least-squares method) and is shown in the figure as the blue curve. The measured optical distortion data is represented by the red crosses. The distortion values are plotted against the radial coordinate as measured (in pixels) from the center of the image. The measured optical distortion as well as the best-fit optical and SMIA TV distortion curves are plotted. The figure to the right summarizes the distortion of lens. ![]()
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