interpolation

Nearest-neighbor interpolation algorithm in MATLAB

由 巧了我就是萌 提交于 2019-11-26 17:45:19
I am trying to write my own function for scaling up an input image by using the Nearest-neighbor interpolation algorithm. The bad part is I am able to see how it works but cannot find the algorithm itself. I will be grateful for any help. Here's what I tried for scaling up the input image by a factor of 2: function output = nearest(input) [x,y]=size(input); output = repmat(uint8(0),x*2,y*2); [newwidth,newheight]=size(output); for i=1:y for j=1:x xloc = round ((j * (newwidth+1)) / (x+1)); yloc = round ((i * (newheight+1)) / (y+1)); output(xloc,yloc) = input(j,i); end end Here is the output

How to perform interpolation on a 2D array in MATLAB

由 ぃ、小莉子 提交于 2019-11-26 17:25:23
问题 How can I make a function of 2 variables and given a 2D array, it would return an interpolated value? I have N x M array A . I need to interpolate it and somehow obtain the function of that surface so I could pick values on not-integer arguments. (I need to use that interpolation as a function of 2 variables) For example: A[N,M] //my array // here is the method I'm looking for. Returns function interpolatedA interpolatedA(3.14,344.1) //That function returns interpolated value 回答1: For data on

How do I double the size of a vector in MATLAB with interpolation?

由 青春壹個敷衍的年華 提交于 2019-11-26 16:56:08
问题 Essentially, if I have the following matrix: [1, 2, 3 ,4, 10] I need to explode it whilst interpolating, as follows: [1, 1.5, 2, 2.5, 3, 3.5, 4, 7, 10] . Essentially, buff it up by filling in the average of the two surrounding values. Say if I need to do this for n instead of adding just 1 value as we have here. 回答1: You need to use interp1 with 'linear' interpolation method: >> v = [1 2 3 4 10]; >> newNum = 13; % new number of elements in the "buffed" vector >> iv = interp1( linspace(0,1

Python 4D linear interpolation on a rectangular grid

由 Deadly 提交于 2019-11-26 16:34:55
问题 I need to interpolate temperature data linearly in 4 dimensions (latitude, longitude, altitude and time). The number of points is fairly high (360x720x50x8) and I need a fast method of computing the temperature at any point in space and time within the data bounds. I have tried using scipy.interpolate.LinearNDInterpolator but using Qhull for triangulation is inefficient on a rectangular grid and takes hours to complete. By reading this SciPy ticket, the solution seemed to be implementing a

Generate colors between red and green for an input range [duplicate]

由 只谈情不闲聊 提交于 2019-11-26 15:48:20
问题 This question already has answers here : Closed 6 years ago . Possible Duplicate: Color coding based on number I want for a user to be able to select from a range from 1-100, where as the numbers become less than 50, the color of the area becomes darker green, and as the color becomes closer to 100, the color becomes more red. I am trying to make it so that as the range in more towards the center, the color should be close to white (where 50 = full white). I tried the answer from here:

How do you do bicubic (or other non-linear) interpolation of re-sampled audio data?

由 ☆樱花仙子☆ 提交于 2019-11-26 15:26:55
问题 I'm writing some code that plays back WAV files at different speeds, so that the wave is either slower and lower-pitched, or faster and higher-pitched. I'm currently using simple linear interpolation, like so: int newlength = (int)Math.Round(rawdata.Length * lengthMultiplier); float[] output = new float[newlength]; for (int i = 0; i < newlength; i++) { float realPos = i / lengthMultiplier; int iLow = (int)realPos; int iHigh = iLow + 1; float remainder = realPos - (float)iLow; float lowval = 0

Interpolate NaN values in a numpy array

由 感情迁移 提交于 2019-11-26 15:15:13
问题 Is there a quick way of replacing all NaN values in a numpy array with (say) the linearly interpolated values? For example, [1 1 1 nan nan 2 2 nan 0] would be converted into [1 1 1 1.3 1.6 2 2 1 0] 回答1: Lets define first a simple helper function in order to make it more straightforward to handle indices and logical indices of NaNs: import numpy as np def nan_helper(y): """Helper to handle indices and logical indices of NaNs. Input: - y, 1d numpy array with possible NaNs Output: - nans,

Reverse complex 2D lookup table

由 自古美人都是妖i 提交于 2019-11-26 14:43:14
问题 I have some function which maps some input to the output . The output is a complex number. What I'm actually interested in is the inverse function . But since this inversion can't be done in a analytical way I need to do it with a numerical approximation. Since is computationally expensive my idea was to use a lookup table approach. I can generate a 2D lookup table with the dimensions (forward lookup table), but what I actually need is the inverse of this lookup table—yielding based on a

How to implement linear interpolation?

由 给你一囗甜甜゛ 提交于 2019-11-26 12:26:27
问题 Say I am given data as follows: x = [1, 2.5, 3.4, 5.8, 6] y = [2, 4, 5.8, 4.3, 4] I want to design a function that will interpolate linearly between 1 and 2.5 , 2.5 to 3.4 , and so on using Python. I have tried looking through this Python tutorial, but I am still unable to get my head around it. 回答1: As I understand your question, you want to write some function y = interpolate(x_values, y_values, x) , which will give you the y value at some x ? The basic idea then follows these steps: Find

How do I implement a Bézier curve in C++?

由 拈花ヽ惹草 提交于 2019-11-26 11:55:20
问题 I\'d like to implement a Bézier curve. I\'ve done this in C# before, but I\'m totally unfamiliar with the C++ libraries. How should I go about creating a quadratic curve? void printQuadCurve(float delta, Vector2f p0, Vector2f p1, Vector2f p2); Clearly we\'d need to use linear interpolation, but does this exist in the standard math library? If not, where can I find it? Update 1: Sorry, I forgot to mention I\'m using Linux. 回答1: Did you use a C# library earlier? In C++, no standard library
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