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6 views

How does I calculate and plot equalized cdf?

I want to know how to get equalized histogram like this Figure 10 in here http://cache.freescale.com/files/dsp/doc/app_note/AN4318.pdf Especially, If you don't mind please let me know as Matlab code. ...
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1answer
13 views

Does anyone know how to overlay a equalized CDF plot with equalized histogram in matlab?

I am willing to overlay a equalized cdf with equalized histogram in matlab. But it's really hard to find any recommends. so if you can, would you please let me know about that?
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0answers
15 views

What does mean that to clipping the histogram value on adaptive histogram equalization? [on hold]

What does mean that to clipping the histogram value on adaptive histogram equalization? Does anyone know how to deal with clipping histogram on adaptive histogram?. Additionally, I would like to plot ...
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1answer
27 views

What does mean Histogram Equalization? [on hold]

Now, I am trying to study Histogram equalization and I refer to the wikipedia article here But I don't understand about $cdf_{min}$ value and $M$ and $N$. Why does $cdf_{min}$ value are decided on 1? ...
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0answers
11 views

Kullback-Leibler Divergence of 2 histograms: Bin width issue?

0 down vote favorite I am calculating the distance of 2 histograms using Kullback-Leibler Divergence (KLD). Of course, the number of bins of 2 histograms are the same. However, I have a question ...
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0answers
16 views

Useful features for classifying color images

I have two sets of images. In one set, the background and foreground differs significantly in color (either background is dark and foreground is light or vice versa). What would be some useful ...
0
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1answer
25 views

Getting 16 bit image statistics in Photoshop

The histogram in Photoshop for a 16-bit image downsamples to 8 bits, showing a tonal range of 0 to 255. I appreciate to show tonal ranges for a 16 bit image a horizontal zoom function would be ...
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0answers
38 views

Gonzalez question solution

If I have the histogram of an input image as Gaussian probability density function of the form: $$P_r(r)=\dfrac{1}{\sqrt{2\pi}\sigma}e^{-\dfrac{(r-\mu)^2}{2\sigma^2}} $$ where: $\mu$ and $\sigma$ ...
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1answer
58 views

Histogram Intersection with two different bin sizes?

I have two images: A and B. Image A is a screenshot of image B, the original image. While there is noise in image A, the original features are still distinguishable. Histogram intersection tells us ...
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1answer
24 views

float image to integer type image

I have a multispectral satellite image and I would like to "transform" each of the image bands into one with integer values. For example to stretch? the image between 0 and 255. Not sure how to ...
0
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1answer
160 views

Histogram matching of two images using cdf

I have already calculated the cdf values of each image now i have to map the reference image values to target . I cannot use histogram equalization or interpolation I simply have to map them . ...
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0answers
56 views

linear contrast stretching based on minimum and maximum calculation from image histogram

I'm studying Gonzalez image processing book and under the topic linear contrast stretching based on minimum and maximum calculation from image histogram has been ...
0
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1answer
184 views

Histogram and binary image in opencv? [closed]

I would like to compute how many zeros and ones (e.i. 255) in a binary image. The following code to generate a binary image by using Matlab. ...
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0answers
101 views

GLOBAL THRESHOLDING using histogram

There is a recursive way of finding threshold in the image using histogram that are biomodal, and is as follows: An automated procedure for bimodal histograms : Select an initial estimate of T ...
1
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1answer
104 views

What steps come after finding the gradients of the SIFT key points?

I am using a SIFT algorithm to extract features from an image. I understand that the SIFT descriptor first finds the extrema and then finds the gradient and direction of each of these interest ...
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0answers
51 views

Distance-metric for SIFT descriptors matching

Will using Cosine-Similarity or Histogram Intersection as distance-metric, for matching SIFT descriptors, help to get better results? Anybody tried on that ever?
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2answers
90 views

How to create a band limited signal of sine waves that is nearly uniform distributed

I would like to create a signal that is nearly uniform distributet (as depicted in Figure 1). It must consist of some single sine waves (e. g. 400 Hz, 430 Hz, 500 Hz) or a random band limited signal ...
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0answers
46 views

Encoding the HOG features

I have got a video containing 200 frames and i am extracting low level features at pixel level. Then i am dividing the entire frame in to small spatial patches (say of size 7x7) and creating a feature ...
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4answers
795 views

Why is histogram equalization called as “equalization”?

When output histogram is not same as reference histogram, why is the method called histogram equalization? For example below are two figures from http://en.wikipedia.org/wiki/Histogram_equalization. ...
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1answer
230 views

Image Contrast Enhancement based Sub-histogram Equalization Technique without Over-equalization Noise

I'm a computer science student and I have an assignment requiring me to implement the algorithm proposed by this paper but I'm hitting a roadblock trying to understand the implementation of one of the ...
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1answer
155 views

Calculating an HSV histogram

I have to compute an HSV histogram of a colored image. Is it same as an H-S histogram? I have found H-S histogram computation code everywhere. What is the method to change an H-S histogram to an ...
2
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1answer
98 views

Histogram evaluation for image quality concerning illumination

I'm currently trying to develop an algorithm to control the camera characteristic of a camera (the camera characteristic can be controlled to adopt it to the different lightning situation which can ...
2
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1answer
66 views

Histogram operation for improving visual object tracking

I'm developping a people tracking with nearest neighbour data association technique and kalman filter for smoothing/predicting. The tracker works quite good but sometimes it mismatch objects if they ...
2
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1answer
1k views

What is use of a gaussian filter over histogram?

I am working in the field of digital image processing and currently i am reading this paper and I have two questions about it.... After applying a gaussian filter to a histogram, will the pixel ...
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0answers
70 views

Optimal image histogram for Human eye

I need to visualize some data as gray-scale images after contrast enhancement. The processing algorithm must be built on few samples, and then it will be applied on unseen images (suppose, the [min, ...
2
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1answer
204 views

Histogram of signal with a time shift added

One of the problems in Proakis's signal processing book using Matlab asks to plot the histogram of x3(n) = x1(n) + x1(n-1) where ...
2
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1answer
565 views

Interpolation in Contrast Limited Adaptive Histogram Equalization

I have been trying to implement the CLAHE algorithm and came across this page which states step by step procedure for the algorithm. I understand the initial steps to perform HE of tiles in the ...
2
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1answer
173 views

Lesser bins histogram looks more equalised than higher bins histogram after histogram equalisation?

I tried to do a histogram equalisation on an image, and then display its histogram. I realise that when I show the histogram with 10 bins, it looks more "equalised" than when I show the histogram with ...
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0answers
107 views

Why histogram equalization fail in ehnanche images for bimodal hisogram?

I'm on histogram equalization process. I have quite well understood the math but i don't understand why an histogram on bimodal image fails in image enhancment and what tecniques can i use in this ...
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0answers
149 views

Local histogram equalization

I want to learn computer vision and so I downloaded image processing slides from my university archive. I'm on histogram equalization. Learning about local histogram equalization points me out to this ...
3
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1answer
325 views

Relation between histogram equalization and 'Auto Levels'

I need to enhance an image using only global linear adjustment of intensity, i.e.: $$I'=aI+b,\qquad a,b\in \mathbb{R}$$ where $I$ and $I'$ are input and output (enhanced) image. I already know how ...
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1answer
618 views

importance of using histogram equalization

I'm reading opencv tutorials and I'm diving into histogram equalization. i have looked in wikipedia, there is a nice example that sums up exactly the problem: original: equalized: but for getting ...
9
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1answer
3k views

Opencv calcHist and calcBackProject in plain english

i've started experimenting with c++ and opencv because of i want to learn image processing. Now, my first exercise is to create a skin detector with calcHist and calcBackProject. But i don't ...