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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Given an image how should I detect this is a day picture or night picture?

I have a 2D image which contains R G and B values. I think this should be purely based on averaging of pixels and selecting the threshold to decided whether this is day picture or night one. Can you ...
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8 views

Histogram equalization - to increase “punch” and to limit local gain?

The exercise 3.6 (Histogram Equalization) in Szeliski's Computer Vision - Algorithms and Applications asks: Convert the color image to luminance (Section 3.1.2). Compute the histogram, the ...
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1answer
33 views

What does it mean for an image to be “Markovian”?

I've been following the recent lectures on Coursera for image processing. In the lecture on the use of the discrete cosine transform (DCT) for image compression, he says that for images that are ...
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2answers
67 views

How to transform or distort or skew a rectangular image to fit arbitrary quad

I have a rectangular image which need to transform so the image fits an arbitrary convex quad. Easy? Except I have an important constraint, the features on the original image must maintain their ...
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1answer
35 views

Is this image good enough for OCR?

Hello I'm trying to ocr on a special image. I've done adaptive threshold , polartocartesian transformation. this is my original image this is adaptive threshold this is polartocartesian ...
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13 views

Gap Filling Contours / Lines

I have the following image: and I would like to fill in its contours (i.e. I would like to gap fill the lines in this image). I have tried a morphological closing, but using a rectangular kernel ...
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1answer
21 views

Classification from a feature vector

I'm quite new to this; I'm try to classify textures as defective or non-defective. I've used a Gabor filter bank with Matlab which outputs a column vector of the Gabor features of an image. I have a ...
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20 views

Noise Removal from an image

What type of filters can be used to remove Poisson noise in an image? I tried applying Gaussian filter to few points in the spectrum.
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11 views

use scale space representation to filter one image

Currently I hope to use scale space representation to filter one image. Features in one image can be filtered using an Gaussian smooth filter with one optimal sigma. It means different features in one ...
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1answer
25 views

Is there a way to perform 2-D image rotation by matrix multiplication?

In my understanding, unlike shifting and scaling, image rotation actually rotates the coordinates whereby interpolating the pixels at discrete positions. It is like a projection that discrete values ...
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13 views

How to calculate the intensity of pixels after histogram equalization

It's a question from an exam that I can't understand its result. Given the following intensity histogram of an image: After an histogram equalization applied for this histogram, we've got the ...
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1answer
24 views

Introduction to IP : Laplacian of Gaussian?

I am very new to the concept of computer vision (and image processing), and trying to understand the algorithm used for edge detection. One thing I'm currently struggling to figure out is the ...
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2answers
120 views

How to remove the noise without destroying the main edge?

I am working on a project. I want to segment a logo from a car and the picture's size is 3648*2432. The logo is selected by the red rectangle. I extracted this area and turn into gray level. The ...
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50 views

Denoise images with wavelets

I try to understand what following algorythm from this gimp plugin does to denoise an image: ...
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1answer
29 views

Avoiding identifying objects within previously identified objects in MATLAB

Apologies if the question title is confusing. I've got some code below in MATLAB, which identifies squares/rectangles in an image. ...
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23 views

Image Registration / Fusion Optimal Similarity Metrics

I have a theoretical question about optimal similarity metrics for comparing data sets. In reading the linked pdf, I read the following 2 interesting statements: "In the ... scenario in which A and ...
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1answer
42 views

Removing periodic noise from image using Fourier transform

I'm trying to get rid of some periodic flicker noise through post-processing of the recorded images. The reason for these artifacts is that the electronic rolling shutter of the camera reads each line ...
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22 views

Image blurring using gaussian low pass filter [closed]

I'm trying to blur a grayscale image using Gaussian low pass filter( 5*5 kernal).I tried the following code. ...
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1answer
80 views

Object Detection Algorithms

I'm a complete beginner to object recognition. I need to identify and count how many of a certain type of Lego, in a picture full of different pieces of Lego, using MATLAB. The pieces of Lego I need ...
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1answer
32 views

Re sizing and thresholding small font scanned Arabic words

I am working on an arabic OCR for printed scanned documents ... Some of the scanned documents may written with font size of height 8 which is quite small ... I want to resize the height to 60 pixels ...
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1answer
19 views

What are characteristics of shadows in an image given an outdoor setting from an image processing point of view?

I'm wondering what basic characteristics of shadows are. I'm looking from a camera image/video processing point of view. I'm considering the case of an outside scene in direct sunlight. These are the ...
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18 views

Classification of shadow border points in an image

I'm working on a problem concerning the classification of features (Fast features in my case) on shadow borders in an image. I would like to discriminate features on shadow borders from all other ...
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0answers
4 views

How to get characteristic quanities from 3-D position files of a porous material

I have position files of a porous media generated by a simulation. The file has three columns for x,y,and z axis positions of particles. And there are many files for different snapshots in time. These ...
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1answer
42 views

How can I convert camera motion into zoom?

I try to reconstruct a camera of a video sequence via match moving techniques. After the reconstruction process all seemed to work as expected, but then I've realized my camera is moving forward ...
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3answers
59 views

Generate projection image by OpenGL or Matlab

I want to generate the "projection" image described as bellow. The left picture is the original picture and the right image is what I want. But, I have no idea about how to generate the right image. I ...
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1answer
49 views

Efficient Marker Detection for Images

I need to detect a known number of simple markers (chessboard patterns) in a color image efficiently. I implemented normalized cross correlation (NCC) as a pixel shader via WebGL since I need this to ...
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1answer
55 views

FFT: Removed padded zeroes?

I have an application where I do this: DFT->Filter->IDFT on a range For computational performance I'm zero-padding my FFT to a power of two, but when I ...
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26 views

Imposing a prescribed motion field to a grayscale image

I have a grayscale image with intensity distribution $I_1\left(i,j\right)$. I am trying apply a motion field $$u\left(i,j\right), v\left(i,j\right)$$ where $\left(i,j\right)$ is the index ...
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14 views

Calculating coefficients of 2D Daubechies Wavelet

I want to implement a 2D Discrete Daubechies Wavelet for image denoise. I can use MATLAB to calculate 1D DB Wavelet coefficient. [LoD, HiD] = wfilters('db4'); ...
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53 views

Horizontal banding (flickering) due to electronic rolling shutters

It is a well-known artifact that in CMOS cameras with electronic rolling shutter, horizontal banding (flickering), i.e. brightness intensity variations, are observed when the image is recorded under ...
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1answer
55 views

Feature Detection on a Circular Metal Surface for Character Recognition

Hello I'm trying to recognize characters on the circular metal surface. Without any preprocessing I could match cropped features with original image. I've actually cropped 2 characters together to ...
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2answers
52 views

Line tracing folowing a path of an almost connected components

say we have a binary image like the one in below i would like to extract each black line, even if it's not almost connected i have marked here in red, example of lines that correspond to those to be ...
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1answer
27 views

Applying lowpass and highpass filters to an image in frequency domain in matlab

What i want is simply to apply low pass and highpass filters to an image in the frequency domain. Does matlab image processing toolbox have any commands for this?
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14 views

Estimate Image power spectrum of the noise

I want to implement Wiener filter. I have original image and image blured with linear motion. The one thing I am lack of(to implement it) is Noise power spectrum. I know that it is hard task. I've ...
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1answer
165 views

Suggested Preprocessing methods for OCR on Circular Images

Hello this is my sample image I am going to do real time character detection on images like that. I've tried SURF, SIFT, MSER and template matching on original image without any preprocessing. I can ...
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1answer
35 views

How can Recognize handwriting number [closed]

Which algorithms should use to recognize handwriting numbers from an image?
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1answer
38 views

Is there any research work on the possible data structures that can be used to represent an architectural design of a building? [closed]

I am looking for a data structure, that can be used for description of a floor plan of a building. Its not about the format, I am asking about any other way to describe the floor plan of building, ...
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2answers
23 views

Is this a image similarity problem?

I want to make a programm that can detect the differences between two similar images of an automotive fusebox. The fusebox will be placed inside a jig and so will usually will be in the same position ...
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1answer
58 views

How to detect the exception by SVM with openCV

I have implemented SVM by openCV. However, I have a problem about SVM with openCV. For example, I have six categories, but I just use "five" of them to train my SVM. When testing, I want my system ...
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0answers
19 views

Trouble understanding Histogram Equalization maths

So I understand what histogram equalization does. To me it seems to be solving a more generic problem of trying to redistribute the probability distribution of a random variable to another so that the ...
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2answers
56 views

How to calibrate three orthogonal cameras?

I am trying to find out intrinsic parameters(focal length ,principle point,and lens distortion coefficients)as well as the extrinsic parameters(rotation and translation of each camera relative to the ...
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2answers
67 views

Image Segmentation - Berkeley Dataset

I've been given an image from Berkeley dataset to segmentate. I am an undergrad student and so far I threw everything i know to this thing. But the colors are extremely close. I tried; Clustering ...
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1answer
33 views

What are the keywords to find an algorithm that detects embossed text from a 3d model?

Currently I am doing an acadmic research about an idea which came into my mind lately. I have a 3d model and I want to extract embossed text .. anyone knows any papers? or if it is already proposed? ...
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1answer
44 views

applying convolution theorem swaps quadrants

For educational purposes I implemented the DFT and inverse DFT for images using OpenCV. Applying the DFT to an image and taking the inverse DFT of the spectrum yields the original image, so this ...
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36 views

How do i detect if an image has a gradient or not?

I have coloured images, some may be just clipart, some may be artwork, both could be with or without gradients. Before i run a colour counting algorithm on them, i want to detect if the image has ...
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0answers
45 views

Why Normalized Cross Correlation Score of different templates is high?

I am using OpenCv's built in template matching function to search for an object in image. I am using Normalized Cross Correlation Method.The function is returning a value which I think indication of ...
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0answers
19 views

Analytical expression for convolution of two 2D DFTs

I am trying to do an image analysis problem on some images, and I want to calculate some things in the frequency domain which are giving me problems. Say I have an (discrete) image $I(x,y)$ of size ...
2
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2answers
55 views

convolution matrix for image scaling

Is there any way how to compute convolution matrix for Nearest Neighbor (bicubic, bilinear) image scaling (upscale/downscale)?
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23 views

SIFT Problem with producing first layer of first octave

[1]Distinctive Image Features from Scale-Invariant Keypoints D. G. Lowe Int. Journal of Computer Vision 60(2) (2004), pp. 91--110' I have read [1] for several times. In Section 3.3, there is a ...
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1answer
21 views

Tracking a Predefined Curve in a Series of Images

I have a series of images. I want to be able to draw a curve on the image and track the curve in the series. For example, in the figure below, the left image illustrates the original image at time ...