histogram

Ok, so I have a histogram (represented by an array of ints), and I'm looking for the best way to find local maxima and minima. Each histogram should have 3 peaks, one of them (the first one) probably much higher than the others. I want to do several things: Find the first "valley" following the first peak (in order to get rid of the first peak altogether in the picture) Find the optimum "valley" value in between the remaining two peaks to separate the picture I already know how to do step 2 by implementing a variant of Otsu. But I'm struggling with step 1 In case the valley in between the two

I have periodic data and the distribution for it is best visualised around a circle. Now the question is how can I do this visualisation using matplotlib? If not, can it be done easily in Python? My code here will demonstrate a crude approximation of distribution around a circle: from matplotlib import pyplot as plt import numpy as np #generatin random data a=np.random.uniform(low=0,high=2*np.pi,size=50) #real circle b=np.linspace(0,2*np.pi,1000) a=sorted(a) plt.plot(np.sin(a)*0.5,np.cos(a)*0.5) plt.plot(np.sin(b),np.cos(b)) plt.show() There are a few examples in a question on SX for

I am trying to perform a histogram equalization using OpenCV using the following function Mat Histogram::Equalization(const Mat& inputImage) { if(inputImage.channels() >= 3) { vector<Mat> channels; split(inputImage,channels); Mat B,G,R; equalizeHist( channels[0], B ); equalizeHist( channels[1], G ); equalizeHist( channels[2], R ); vector<Mat> combined; combined.push_back(B); combined.push_back(G); combined.push_back(R); Mat result; merge(combined,result); return result; } return Mat(); } But when I get the result, there seems to be no difference in input and output image, what am I doing wrong

In ipython Notebook, first create a pandas Series object, then by calling the instance method .hist(), the browser displays the figure. I am wondering how to save this figure to a file (I mean not by right click and save as, but the commands needed in the script). Phillip Cloud Use the Figure.savefig() method, like so: ax = s.hist() # s is an instance of Series fig = ax.get_figure() fig.savefig('/path/to/figure.pdf') It doesn't have to end in pdf , there are many options. Check out the documentation . Alternatively, you can use the pyplot interface and just call the savefig as a function to

As far as I know the option Log=True in the histogram function only refers to the y-axis. P.hist(d,bins=50,log=True,alpha=0.5,color='b',histtype='step') I need the bins to be equally spaced in log10. Is there something that can do this? HYRY use logspace() to create a geometric sequence, and pass it to bins parameter. And set the scale of xaxis to log scale. import pylab as pl import numpy as np data = np.random.normal(size=10000) pl.hist(data, bins=np.logspace(np.log10(0.1),np.log10(1.0), 50)) pl.gca().set_xscale("log") pl.show() The most direct way is to just compute the log10 of the limits,

i want to show image RGB colour histogram in cocoa application. Please suggest possible way to do it with objective c or any third party library available to achieve this. Spektre well this is a problem as RGB colors are 3D space so their histogram would lead to 4D plot which is something we do not really comprehend. So the solution to this is to convert the 4D plot to 3D plot somehow. This can be done by sorting the colors by something that has some meaning. I will not speculate and describe what I am using. I use HSV color space and ignore the V value. This way I lose a lot of color shade

I like to make a histogram. With drawLine() , it's not really a problem for me, but when I try to do it with fillRect() the rectangles are going from top to bottom. I would like to paint the histogram looking similar to my histogram with drawLine() . Here is my code: public void paint(Graphics g) { super.paint(g); int height = getHeight(); int width = getWidth(); int x =10; haufigkeit=model.getMap(); for(int i = 1; i <= 45; i++) { int y; y = haufigkeit.get(i); Color color = new Color(0, 0, (int)(150 + Math.random() * 100)); g.setColor(color); // g.fillRect(x, 50, 10, y); // g.drawLine(x,