In general, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame.

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Accurate Image Resizing

I need to resize an image using bilinear interpolation and create an image pyramid. I will detect corners at the different levels of the pyramid and scale the pixel co-ordinates so that they are ...
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37 views

What do Skewness and Kurtosis represent?

I understand that the question could mean a lot of things but I am thinking specifically to image processing. For example, I know that the mean can be a basic texture feature that represents the ...
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9 views

Analytical expression for salient Blob detection in scale space

I am working on exact mathematical expression which can be obtained in image processing tasks.(I do not know much about image processing but my work is more mathmatical) In Gaussian scale space, we ...
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29 views

Object detection in binary image

This task comes from tracking object on a steady background. So far I was able to remove the background and obtain binary masks like this: I need to get bounding rectangle of the toy without the ...
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19 views

How to set threshold value for Hough Transform

I am new to Computer Vision, I am writing my own code for Hough Transform I have found the following algorithm: Algorithm: ...
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40 views

Replace phases of image FFT

I have 2 images of the same scene, captured by different cameras. So they a bit displaced. As far as I can understood, phases of FFT contains info about image details. My goal is to take intensity ...
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How to understand the implementation codes in Debevec and Malik's HDR paper

The paper titled "Reconvering High Dynamic Range Radiance Maps from Photographs" from Debevec and Malik is a seminal paper in high dynamic imaging. In this paper, it proposed a method to estimate the ...
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12 views

Edges in Content Based Image Retrieval (Java)

I have developed a programme that currently computes the standard deviation. I am trying to alter this algorithm so that it can extract the edges of an image. I have been told I can do so if I build ...
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55 views

Which is correct representation for function of variable?

I have a function as $$E=\int_\Omega -\log\big( p_i(x)\big) dx$$ where $p_i(x)$ is density distribution which estimated by Parzen window method. $$p_i(x)=\frac{1}{\Omega_i} ...
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24 views

Is it possible to rewrite gradient magnitude of Sobel in continuous formula?

Let $*$ denote a convolution operation, $G$ denote a kernel, and $I$ is a given image. The gradient of the image $I$ is equivalent: $\nabla (G*I) = (\nabla G) * I$ The Sobel filter approximtes two ...
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36 views

Segmentation of small artifacts - Image Processing

I am working on a task of segmenting small artifacts from a set of images like below: I am looking for a generic approach, but unsure of what to search? I tried looking at density flow analysis, but ...
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49 views

What is the difference between the terms color Intensity and color Saturation?

In Digital Image Processing, what is the difference between the intensity and the saturation of a color? How would you explain the difference to a newbie?
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59 views

Removing noise from dental radiography

I'm working on a project of applying Active Shape Model to locate tooth in dental radiograph. For those familiar with the technique, I'm currently trying to sample along normal vectors for each ...
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22 views

How image masking works?

I am new to image processing and I am interested how image masking can be used to extract a portion of a image. Have a look at this OpenCV tutorial. In the section Application of Mask, they say that ...
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1answer
24 views

Basis functions in DCT

I'm new to Discrete Cosine Transform (DCT) and I have a question relating to basis functions. In DCT, basis functions are defined by: $$\alpha_p\alpha_q\cos\frac{\pi ...
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1answer
20 views

Image Scrambling versus Image Encryption

What is the difference between image scrambling and image encryption or are they the same thing in the context of image processing? What about in communication systems in general?
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42 views

processing photo diode array data

We have designed a system which has an 8X8 array of photo diodes, we sense 10ns pulses of laser falling on those photo diodes with a repetetion rate of maximum 50Khz i.e. 20us, we were successfully ...
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15 views

How to design Bi orthogonal wavelet filter bank

I know in orthogonal wavelet system analysis filters can be made by flipping the synthesis filters(vice versa) but in bi orthogonal system this will not work because the co efficient are symmetric in ...
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2answers
43 views

Accessing maximum value from singular value decomposed matrix

I have read few image enhancement papers, where an image is enhanced in transformed domain using either DCT or DWT with SVD. Few of such works can be studied from link_1,link_2, link_3 . In these ...
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12 views

MPEG: Predictive Coding and transmitted error

I was given a predictive coder that uses this predictor: x = (C + 2B + 2A) / 5 A B C x I need to find the transmitted error for the current line ...
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37 views

Importance of Discrete Cosine Transform over High Pass filter?

I have recently studied few work where the low and high frequency components of an image is accessed using the discrete cosine transform (one such example is presented here). Low and High frequency ...
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70 views

How to calculate particles sizes for spheric particles with overlapping and superposition? (Example image included)

I'm trying to automatically calculate particles sizes histogram for images like this one: Common threshold and segmentation doesn't seem to work. What filters and algorithms do you suggest to be ...
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20 views

Approximate LoG using DoG

I read in Lecture 11: LoG and DoG Filters (Robert Collins) that the Laplacian of Gaussian (LoG) can be using a difference of Gaussians (DoG) and that it is best approximated when $\sigma_1 = \sigma / ...
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17 views

What is the difference between “tree-based clustering” and “tree-based classification”?

Clustering is an unsupervised learning method and classification is a supervised one. I understand that a tree can be used for image classification since it is based on decision tree in which we have ...
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52 views

Using a median filter to constantly monitor to identify a laser strike in any of the known laser wavelengths

We would like to design a proof of concept using a flight simulator cockpit similar to one that flies with passenger to prototype a system for blocking coherent laser pointer beams aimed at commercial ...
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21 views

Asking about the steps of SIFT?

I am a newbie about Computer vision. I am reading about the SIFT detector but I can not understand the step find subpixel maxima/minima and step eliminate edge and low contrast region. Can anyone give ...
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34 views

Possible to shift image pixel-wise with FFT?

I know we can shift an image entirely with FFT as http://stackoverflow.com/questions/25827916/matlab-shifting-an-image-using-fft However, is it possible to shift the image pixel-wise? I just found a ...
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32 views

Oversampled Binary Image Sensor vs Active Pixel Sensor(CMOS)

I am a beginner in the field of Image processing.I was designing a camera sensor when I came across these two type of sensors: CMOS(Active Pixel Sensor) Oversampled Binary Image Sensor. Now, I can ...
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52 views

Best reference for object size estimation in an image

I'm working on a project where I need to measure the size of a 2D object on a flat surface from an image. I have total freedom to create a reference with any shape and size. The camera I am using is ...
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37 views

How to properly detect segments in a LCD segment display

I have been given the task to develop a code which checks if the display of a device is showing information correctly (i.e. any segments are activating when they are not supposed to). To meet this ...
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35 views

How to classify images based on the amount of colors in the image?

I have a problem where all images have the same object; however, these objects can either have number_of_colors<=3 OR number_of_colors>3 and images are not labeled. My attempt starts by ...
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2answers
33 views

Wavelet filter coefficients from scaling filter coefficients

I am trying to develop a new type of wavelets and I found out a function that following a particular two scale relation. The function at a scale $t$ say $x(t)$ can be related in a finer scale $x(2t)$ ...
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12 views

how to project images in different angles?

My theoretical knowledge in image processing is not all that good. I was reading a paper when I came across the following: To carry out such a comparison, we simply rotate from 0 ◦ to 180 ◦ and ...
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52 views

How to replace color in an image without changing its texture/shades or brightness?

I want to replace color in an image from another color: For that sample image is below I want to replace color such that it becomes I know it can be easily done in Photoshop but I am looking ...
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23 views

How to filter objects on basis of orientation of regionprops

I am trying to detect straight vertical lines in an image. I used vertical edge detection and then I tried to check which objects has the ...
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11 views

Automatic landmarks on images of hands

Problem statement I am starting a project soon where I need to create a method to automatically create landmarks on a set of images of human hands. I do not have a sample image but the images are ...
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20 views

Image Rotation using 3 Shears, Implemented using FFT-based Shifts

So I'm trying to rotate an image using the 3-pass shear. We're implementing the 3 shears in Fourier space, so we're taking the the rowise/colwise FFT, then multiplying it with e^ikx, with necessary ...
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18 views

Why sparse prior like total variation opts to concentrate derivatives at a small number of pixels?

When performing image deconvolution (deblurring), people often make use of priors to get rid of the illness of the problem. One very common prior is total variation, a sparse prior. Compared to ...
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35 views

What are Local and Global In-painting techniques in Image Processing?

Is Diffusion-based inpaiting Local or Global? Is Pixel-based inpaiting Local or Global? Is Patch-based inpaiting Local or Global? Can Local-diffusion be used inside Patch-based in-painting problems ...
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1answer
20 views

What does Smoothness Prior mean in the context of image processing?

I can quote from an article: "The first category of methods, known as diffusion-based inpainting, introduces smoothness priors via parametric models or partial differential equations (PDE) to ...
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27 views

Finding crosses and their orientation on a given image

I want to recognize table structure from some arbitrary photo image and store it in some formal notation (Let it be HTML table notation). For example I have this blurry image as input: After ...
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Can Inpainting and Texture Synthesis address same types of image-restoration problems?

Are In-painting and Texture Synthesis used to address different types of problems? For instance, can both methods operate on damaged Old photographs and wooden textures? Are these methods ...
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35 views

How to specify 2-D coordinates of an object in matlab?

This is the scenario: I marked two axes (figure below) on a board and a camera(global vision system) sees the board. I want to make the vision system to recognize $X$ and $Y$ axes and specify ...
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32 views

How to implement a $j$-level $M$-band wavelet transform of an image?

I want to implement an $M$-band (or multi-band) wavelet transform, to be used for feature extraction on images. Is there a built-in Matlab function available? Do I have to implement is using filter ...
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1answer
69 views

How does an Image filter really sweep an Image?

Suppose, we have the following image: Now, we want to apply a 5x5 filter to the image. How would the filter sweep the image? Like this? Or, like this? Or, anything else?
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51 views

how to detect two parallel lines in a binary image with MATLAB

I am working on license plate detection using hough transform. I am trying to detect the horizontal and vertical edges and then to find the parallel lines. My ...
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13 views

How to protect an image content so that it can be homomorphically processed?

Let's assume I want to protect an image content. I do not want anything to be revealed about its content and at the same time I want to do some processing on my "secured" image. How to achieve this ? ...
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73 views

What does it mean by Gradient/Divergence/Curl of a 2D Image $g(x,y)$?

Suppose, a 2D image is represented by g(x,y). Then, what does it mean by "Gradient of g(x,y)", "Divergence of ...
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29 views

What is the difference between MRF and Total variation in noise removal?

I have a general question in image processing. I have a noisy image. I would like to classify the noisy image into some regions. Two famous approaches I can use are: MRF/Gibbs MRF: Model the spatial ...
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What does it mean by “Adding Gaussian Noise to a 2D Image”? [duplicate]

As far as I understand, Suppose, we have a 2D image of pixel resolution 200 x 300. That means, the image has 60000 pixels in it. Now, we would generate $n$ random values and add those values to $n$ ...