Questions tagged [image-analysis]

Image Analysis is the extraction of meaningful information from images; mainly from digital images by means of digital image processing techniques.

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Detecting a large horizontal band in the center of an image

I have a small (228x228) grayscale image that I have created by segmenting the original image and converting it to grayscale after applying colors to the segment. I want to know possible approaches I ...
requiemman's user avatar
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How did law enforcement recover fingerprints from the "blue cheese encrochat picture"

I hope that my question suits well within the topics discussed in this SE website. It was reported some time ago how a man was identified after he shared the photo on the encrypted messaging service ...
user71107's user avatar
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Converting cutoff_frequency_ratio to Cycles/Pixel in Butterworth Filtering with skimage

I am working on my thesis where I'm employing Butterworth filtering on images using the function butterworth from scikit-image's skimage.filters module. The code/formula I'm referring to is available ...
AltunE's user avatar
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Detect Longest Vertical Lines (Edges) in an Image

I have a task in image processing, which need to detect vertical lines from matrix. For example, there is a pair of white and black vertical lines segmenting the picture below. I need to find it. So I ...
Jun Yang's user avatar
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1 answer
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Segment Image of Small Elements on Neutral Background

I have a 8 bit gray level image where if the value = 122 it means no information, value = 0 means highly negative, and value = 255 means highly positive. I want to connect as many positive information ...
MistaZ's user avatar
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Distinguishing between intensity image plots

I have a series of intensity images generated by varying different scatterer geometries. An example of variation observed by varying the aspect ratio of these geometries is shown below in the three ...
Shiva's user avatar
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1 answer
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Interpreting results of Sobel Edge Detection

I am implementing A No-Reference Perceptual Blur Metric paper. Somewhere in the prep steps they mention the use of vertical Sobel filter for finding vertical edges. The algorithm is summarized in Fig....
Howisitgoing's user avatar
5 votes
2 answers
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Slicing an Image into Tiles According to Content

Given an image that contains an NxM grid of icons with text below them, somewhat like this: I'm wondering how to split it up into the individual icons with text. Some wrinkles: The image won't ...
bjnord's user avatar
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How to find sharpness of an image?

I have a rather difficult image processing image. I would like to rank order a set of images I have by their sharpness. The issue is the images themselves are not of the exact same thing. Usual ...
user2551700's user avatar
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Blended use of DoH and LoG for blob detection, is there any paper I can cite for this?

tl;dr: For blob detection, I determine locally maximal DoH responses in image regions which correspond to negative LoG responses. Is there publication I can cite for such blended use? Two of the most ...
kostrykin's user avatar
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Detecting Intersections of a Ray with a Polygon

As a part of a math essay, I am writing a program that detects intersections of a line that is drawn with a shape that is inputted. For example, in the shape below, The polygon is the input image of ...
Nishka Arora's user avatar
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Computationally Efficient Ways of Determining If Pixels Are Clumped

I'm working on an application where I get a video frame that's already segmented into good and bad pixels (as in -- the hardware either coughs up a pixel value or a flag that says "bad"). I want to ...
TimWescott's user avatar
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Estimate Local Noise Intensity in an Image

Noise can be assessed in uniform regions of an image, by subtracting a lowpass-filtered version of it. Then from the histogram of intensities, a global measure can be obtained (such as the average ...
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What are the advantages of wavelet transform for image multiresolution analysis? [closed]

Compared to gaussian pyramid and laplacian pyramid, what are the advantages and disadvantages of wavelet decomposition for multiresolution image analysis? Thank you.
Kaiwen's user avatar
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Excluding points too close to a set of coordinates

I was wondering if anyone can help me. My ultimate aim is to take an image like the one shown and draw line between the white and black blobs that show a direction and output the coordinates in the ...
Kilian 's user avatar
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Gaussian pyramid: why needs the image to be downsampled

In the context of a gaussian pyramid, why is the image downsampled separately although the numbers of pixels are decreased through smoothing already? In my understanding, the number of pixels will ...
yPennylane's user avatar
3 votes
1 answer
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How Can PCA Be Used in Image Analysis [closed]

I am still a not how PCA can be used in image analysis and where is it is mostly used. For example how can PCA be used in order to differentiate between different faces? Can you please mention other ...
suyol854's user avatar
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Find the Mid Point of a Worm / Chain Like Object

I have a video of worm-like objects which move. They can move in a straight line, they can rotate in circles, they can move in a serpentine/winding/sinuous way. I need to track them. I already have ...
JalfredP's user avatar
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Compare Active Contours Segmentation (Snake) to Level Sets Segmentation

I am reading about segmentation and I cannot seem to figure out why use active contours over level sets and vice versa. Basically the way I understood it, level sets is relatively the same ...
dsax7's user avatar
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1 answer
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Sharpness in DCT domain image

How can we calculate the sharpness of an image with discrete cosine transform (DCT) domain? Is it worthy in image quality assessment?
usman's user avatar
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Estimate Most Focused Image

I am trying to find the image which has the optimum focus of a focus stack (10 images). I am able to find the best two images by using the minimum gray intensity values but now the problematic part ...
snowflake's user avatar
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Find best fitting rectangles after applying edge detection

I am trying to implement a box detection algorithm. In my pipeline, I start with image warping to simulate a frontal view of the shelf containing the boxes (assuming boxes are straight in that ...
Mehdi's user avatar
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Segmenting Cheese Microstructure (Segmenting Circles)

I'm trying to get the internal geometry of cheese from images of its microstructure: I tried the canny edge detector and otsu thresholding but neither of these worked very well. I'm guessing that I ...
Aidan Rocke's user avatar
1 vote
2 answers
3k views

Measuring sharpness/contrast for autofocus

For the implementation of an auto-focus for the raspberry cam I need some measure of image sharpness. I used the following sample picture: The first approach was to compute the shannon entropy of the ...
Anton Alice's user avatar
2 votes
1 answer
103 views

Primitive Feature Detection to Detect a Black Circle within an Image

I am trying to check whether this black circle is exist or not on my images. My current approach is like that; Hough Circle detection Crop the outer roi Adaptive threshold count zero pixels if ...
Anar Bayramov's user avatar
12 votes
2 answers
11k views

Why Is the Canny Edge Detection Used Instead of Sobel / Prewitt Edge Detection Before Hough Transformation?

I know that for the Hough Transform to work on an image, it needs to be a binary image. To convert from a grayscale image, an edge detection algorithm should be employed. I notice that people always ...
AshivD's user avatar
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4 votes
2 answers
1k views

What Does Multi Scale Image Analysis Mean?

I'm reading an article about multi-scale representation of image, and it is said that, convolving the image with a Gaussian kernel at different $\sigma$, then ...
avocado's user avatar
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1 vote
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Finger print skeletonization without using matlab functions

I am trying to thin foreground pixels of a finger print until they are one pixel wide without using the built in bwmorph and thin operations. Can anyone explain to me how to write them in matlab ...
Rick Grimes's user avatar