Questions tagged [image-processing]
This tag is for the mathematics involved in the field of image processing. Many such questions are also appropriate for Signal Processing Stack Exchange.
669 questions
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How to Correctly Apply an Affine Transform to a Grid of Overlapping Images?
I’m working with a grid where each cell contains an image with a bounding box, and adjacent images overlap. Users can click points on the grid to define source–destination point pairs, and I compute a ...
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How to interpolate image embedding from one image frame to another
I am new to image processing from the perspective of embedding. Currently a lot of research and papers are being published in deep learning community for object detection using transformers. I have a ...
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How to turn an affine reconstruction to a metric reconstruction knowing angles?
I have an affine reconstruction of a 3d scene obtained by using the factorization algorithm (as described on chapter 18.2 of Multiple View Geometry in Computer Vision) on 3 views from affine cameras. ...
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Why doesn’t the barycenter method detect subpixel displacements where correlation does?
I’m working with X-ray imaging data. I have a reference image containing a structured pattern, and a sample image where this pattern is slightly distorted due to the presence of a physical sample. My ...
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Rectifying radial lens distortion
I have an image with lens distortion determined with 7 radial distortion terms $k_1$ thru $k_7$ calculated using the collinearity equation given by where the lens distortion is given by Since ...
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Variable splitting on helping with non-differentiability
I am working on an implementation of deconvolution and Wang et al.'s paper$^\color{magenta}{\dagger}$ mentions something I do not quite understand. The objective function is, in essence, $$\min_u\...
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The rank of the matrix of Fourier coefficients
If I have a rank r matrix $A\in \mathbb{R}^{n\times n}$, $r<n$. If we do a discrete fourier transform on $A$, we get $\hat{A}$. my question is that the rank of $\hat{A}$ is still r or not. I did ...
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Math art: Introducing sinusoidal pixel shifts
I'm working on some math-inspired art. The general premise is to establish a grid corresponding to pixel locations and for each square defined by points $(x_1, y_1), (x_2, y_2)$, determine the RGB ...
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Are There Segmentation Algorithms Based on Mathematical Morphology Other Than the Watershed Algorithm?
I’m a mathematics student currently working on my thesis, which focuses on implementing computational algorithms for image segmentation based on the theory of mathematical morphology. At this stage, I’...
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How to evaluate the quality of reconstructed images by phase retrieval
I am trying the Fienup's hybrid input-output algorithm (This is not so important for the question) to reconstruct a photo. the problem is that I sometimes will get some "shifted" picture, ...
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Transformation for Ellipse with Moving Focus Point
I am hoping that there exists a transformation as performed in this image that changes the eccentricity of an ellipse, but preserves the major axis length. I have been spending today looking into ...
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low resolution picture reconstruction via DFT
I am sorry for my poor statement. For a phase retrieval problem, we know the magnitude imformation of the fourier data, i.e. $|\hat{x}|$, and we need use the imformation to reconstruct $x$. My ...
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Can matrix multiplication define rough "zero borders" in another matrix?
Imagine a grayscale image, $M$. We know that somewhere within $M$ is a dark spot $S$ with brightness values of $0$. Can we find the borders of $S$ using block matrix multiplication, such that the ...
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Calculating Line Intersection Points with Image Borders
I am working on a geometric problem involving a line defined by: A midpoint (X,Y), A directional vector (Nx,Ny), An image of dimensions (width,height). [![enter image description here][1]][1] My ...
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How to describe tilting a 2D signal mathematically?
Title: How to describe tilting a 2D signal mathematically? Hello, How can I describe the following mathematically? A 2D signal $f(x, y)$, e.g., an image, is tilted to become $f(ax + by, y)$, and then ...
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