Questions tagged [image]
This tag covers signal processing where input is an image, such as a photograph or video frame and the output could be an improved or altered image, parameters related to the image or information about features within the image.
462
questions
1
vote
1answer
29 views
Is it okay to interpolate between overlapping areas obtained using a sliding window?
I am using a 50x50 pixel sliding window which moves left to right every pixel so that it covers a whole binary image which is about 2000x2000 pixels. In the window, the ratio value of black to white ...
2
votes
3answers
146 views
What does this paragraph mean?
I'm reading this paper about about an algorithm to measure image sharpness, and am confused by these sentences in the 6th paragraph:
It is well known that the attenuation of high-frequency content ...
0
votes
0answers
15 views
Standard Deviation of Character Gradients in a Document Image
I have the paper titled "CG-DIQA: No-reference Document Image Quality Assessment Based on Character Gradient". It is all about assessing the quality of the document image based on its blurriness. To ...
0
votes
0answers
112 views
Algorithm that Fills the White Holes Within the Character Image
I have this degraded image :
Using paintbucket tool in Paint.NET Windows application, I fill the character image black.
My ...
1
vote
0answers
15 views
What is Maximally Stable Extremal Regions (MSER)?
In the paper , MSER is being defined. Please help me understand what is MSER and how to implement it.
The paper says,
The regions are defined solely by an extremal property of the
intensity ...
0
votes
1answer
13 views
Comparision between SSIM and MAD Image Quality Assessment Algorithms
I have been working with Most Apparent Distortion(MAD) tool to evaluate the quality of images. I have read a paper that compares SSIM, PSNR, FSIM, etc. with MAD. I am uncertain about some calculations ...
0
votes
1answer
30 views
Image Processing [closed]
I have an image and I am trying to find its rows and columns.
A = imread('lena.jpg');
nrows = size(A,1)
ncols = size(A,2)
This is 3 dimensional matrix. Output ...
0
votes
1answer
20 views
Regarding the nature of white noise in images
I have just started learning the very basics of noise.
I have come to understand what white noise is in sound samples, but I do not understand the meaning of white noise in images.
In sound samples, ...
0
votes
2answers
32 views
Average image over $N$ frames with one frame buffer
Can you give some filter that is averaging an image over $N$ samples in a recursive way that only needs one frame buffer?
$\frac{1}{N} \sum_{k=1}^{N} y_{k}(m,n)$
I can only imagine filters that need ...
0
votes
0answers
16 views
How do you apply DCT steganography on an RGB image?
I am working on a DCT-based steganography program in Python and I found a working model in Github. The program, however, can only encode on one of the RGB channels. Resulting in a discolored image. ...
0
votes
0answers
45 views
Maximally Stable Extremal Regions (MSER) Implementation in Document Image Character Patch Identification
My task is to identify character patches within the document image. Consider the image below:
Based from the paper titled "CG-DIQA: No-reference Document Image Quality Assessment Based on ...
0
votes
0answers
17 views
Why is my Fourier descriptor not rotation invariant?
I am trying to implement a simple contour based Fourier descriptor to classify some MNIST images. Nothing fancy.
As expected, if I discard the first coefficient, I achieve translation invariance. ...
1
vote
1answer
28 views
Identify if a Specific Edge Pixel Belongs to Horizontal, Vertical or Diagonal Edge Line
I have a code below that identifies the edge of the text image. Input image is:
Output display is:
I want to select random points near the edge border of the text. I was thinking to identify if the ...
0
votes
1answer
29 views
How is downsampling and low-pass filtering done in MS-SSIM?
I am just studying the Multiscale Strutural Similarity measure for image quality and going through the original paper [1].
I think I understood the basic ides and "regular" structural similarity, but ...
0
votes
0answers
7 views
Need to calculate the VARIANCE of GLCM matrix of an image in MATLAB
I have calculated by Matlab the four characteristics of texture derived from the GLCM or co-occurrence matrix (entropy, contrast, correlation, energy) but in what way can the VARIANCE be calculated ...
0
votes
1answer
39 views
Measure how Straight/Smooth the Borders are Rendered in an Image
I have two images:
I want to measure how straight/smooth the text borders are rendered.
First image is rendered perfectly straight, so it deserves a quality measure ...
0
votes
0answers
22 views
Dirty Image Quality Assesment Measure
I was looking for a way to measure how dirty is the document in image processing. Example images below:
a. Dirty Backgrounds
b. Dirty Backgrounds with Text
Can someone give me an initial idea to ...
0
votes
0answers
50 views
IQ to RF conversion
I appreciate any help:
I wanna convert IQ data to its RF data, representing an image. The centre frequency and sampling rate are available. What I do is:
First I do up-sampling in MATLAB by ...
0
votes
1answer
25 views
Modifying sizes and thickness of letters to “embed” an image in text
I am wondering if this is defined, names and possibly solved - suppose I have a grayscale image and about one page worth of text. I would like to attempt to give the text an appearance of an image ...
0
votes
1answer
42 views
Why we need Laplacian for edge detection?
I am studying some trivial computer vision processing techniques and I came across edge detection algorithms. IMO sharp changes in the gradient are enough indications to detect the edges in an image ...
1
vote
1answer
48 views
How to compute an old style shore line drawing?
I wish to represent a shore line, old-style, as in the following image (city on the left, water on the right):
UPDATE: new image for another example of what I'm after, namely the thin lines (given ...
2
votes
1answer
25 views
Describing a certain quality of an image
Generally I guess I’m asking for a source of image processing terminology.
Specifically here I’m trying to find the word for the quality that would identify the main difference between the Mondriaan ...
0
votes
0answers
15 views
Grading Images According to the Noise It Contains
I have collected a lot of dirty blank pages and each image is varied in the noise it contains. How will I grade images according to the noise it contains in terms of amount, and other aspects? What ...
0
votes
0answers
13 views
Overlaying A Distorted Text According to its Background
I have several dirty background images, sample image is below:
I want to overlay a text on it but I want the text to be as distorted as the background. Example, if the background is a bit wavy, I ...
0
votes
0answers
11 views
Measure that Compares an Actual Old Document from a Synthetic Old Document
I have collected dirty background images, below is the sample:
I have also a collection of an actual image of a dirty document with text on it, just like below:
My problem with my actual image of a ...
0
votes
0answers
10 views
active contour without edges
i am new to image segmentation.i am studying chanvese ACWE paper1.This is level set equation of chan vese paper ACWE.
Above, μ,ν,λ1,λ2 are real parameters, c1,c2 are constants determined for ...
0
votes
1answer
39 views
Comparing spectra from hyperspectral images
I extracted the mean spectra of regions of interests of different tissues from hyperspectral images. How to compare those spectra by the difference of their reflectance and their spectral behavior (...
0
votes
1answer
30 views
Fixing edge/pixel defects in image
I have a large number of images that are supposed to look something like the top part of the image:
Instead, some have defects in them, as in the bottom part of the image. As you can see, there are 2 ...
0
votes
0answers
48 views
How to improve interpolation for chroma upsampling (4:2:0 to 4:4:4)?
I am trying to perform the best possible interpolation in order to perform proper chroma upsampling from 4:2:0 YCbCr to 4:4:4 YCbCr. I have implemented the improved interpolation proposed at this ...
0
votes
0answers
16 views
Finding Duplicate Pixel/Objects along Image seams
I have a seam of two photos joined by a seam alignment algorithm that on occasion generates duplicated pixels/objects/artifacts on both sides of the seam in the final, aligned photo. The images are ...
0
votes
0answers
134 views
What is the definition of the bsd68 dataset?
If I just google "bsd68 dataset", I find this page which allows to download the whole BSD dataset, with all 300 images (potentially 500).
However, I have no idea which of the 100 test images are ...
1
vote
2answers
1k views
Running the BM3D Denoising Algorithm in Python
I am looking for a strong baseline in image denoising and therefore wanted to have the BM3D algorithm in my benchmark.
These 2 python implementations:
https://github.com/ericmjonas/pybm3d
https://...
1
vote
1answer
257 views
Generating Kawase Blur Kernels to Approximate a Gaussian Blur on an Image
Is there an algorithm to generate the Kawase Blur Kernels to approximate the actual Gaussian Blur (of a specific kernel size, and if possible, a sigma)?
1
vote
0answers
41 views
Randomly Generate Synthetic Noise in an Image Text Document
I'm working on denoising dirty image document. I want to create a dataset wherein synthetic noise will be added to simulate real-world, messy artifacts. Simulated dirt may include coffee stains, faded ...
0
votes
0answers
24 views
What does dynamic range values in SSIM image quality technique refers and how to calculate?
http://en.wikipedia.org/wiki/Structural_similarity
Below is java implementation of SSIM.
...
2
votes
2answers
57 views
What are the measurable factors of image sharpness?
I need a way to present data on an essay written about image sharpening algorithm. So I've thought that if I measure a factor of sharpness from image or relative sharpness (between test img and ...
0
votes
0answers
10 views
Want to create a function that calculates the ISO and Shutter speed based on the brightness of previous image
I want to calculate the shutter speed and ISO of Picamera using the brightness information of the previous image I captured.
I have already calculated the brightness of the previous image but I am ...
2
votes
1answer
149 views
Estimate Variance of Additive White Gaussian Noise (AWGN) Given Multiple Realizations with Different Mean
Given $ N $ images of the same scene, where each image is corrupted by additive white Gaussian noise of the same variance $ {\sigma}^{2} $. How can $ {\sigma}^{2} $ be estimated?
So we have an Image $...
0
votes
0answers
39 views
Matching Coordinates between two images
I am using images and corresponding lidar values for depth estimation CNN. I have RGB images. Corresponding to each RGB images, there is another image representing a subsets of pixels and distances to ...
3
votes
1answer
198 views
Strong (0,0) pixel among an otherwise normal cross correlation peak
I am working on an imagery registration problem via cross-correlation and am seeing a weird phenomena sometimes. First, I am pre-processing each image by subtracting the mean image brightness from ...
1
vote
1answer
79 views
Generating spectrogram for band-pass filtered wav file python
I have some .wav files of heart sounds. I want to apply band-pass filter [20Hx 100 Hz]. Then generating PCG images size of 560x420 pixels and RGB format. How could i do this?
Any help will be highly ...
2
votes
0answers
54 views
Combining two images with different resolutions?
I am attempting to combine two radar images, each of which is a 3-dimensional cube with a range dimension, an azimuth angle dimension, and an elevation angle dimension. One image has high azimuth ...
0
votes
0answers
43 views
Face image quality assessment
I'm trying to filter out bad face images (with artifacts) generated by StyleGAN.
Is there a good image quality measurement mechanism in python for doing this?
I've tried using BRISQUE but it is not ...
1
vote
1answer
194 views
How are line pairs and pixels related in image resolution?
I hope this is the correct place to ask this. If not, please refer me to a better place, thanks. Now to my question,
I am learning about digital image processing, and the book I am reading is ...
2
votes
1answer
30 views
Understanding the resulting image matrix when differentiating image
Let $A$ be a image matrix and let $P(i,j)$ be the gray level of pixel $i,j$. Let $0$ be black and $255$ be white Assume I want to differentiate this image with respect to the columns $(x)$ as in I ...
3
votes
4answers
1k views
what is the difference between YUV format and HSV format?
i wonder why HSV and YUV are different formats, even though they both works similarly (based on the brightness), if not what is the difference and i have confusions with YPbPr and YCbCr , can anyone ...
0
votes
0answers
18 views
Efficient image matching technique for small match library set
Background
A scene captured from video frames from an Android mobile device camera are to be analyzed in real-time. The scene will contain up to 12 distinct photos. The library images to be matched ...
1
vote
2answers
23 views
Recommended Order of Performing Denoising, Deblurring and Super Resolution on an Image
In the normal workflow of image processing, there are multiple operations, increase image contrast, image denoising, image deblur and image super-resolution. What are the sequence/order of performing ...
2
votes
1answer
63 views
Localized Gamma Correction
Question:
Is there an algorithm that does (what I would call) "localized" gamma correction?
That is, applying different gamma corrections on different parts of an image, using a masking filter or ...
0
votes
0answers
22 views
Measures of edge image continuity and connectivity
Suppose I have a scalar image $I:\mathbb{Z}_{1,m} \times \mathbb{Z}_{1,n}\rightarrow [0,1]\subset \mathbb{R}$, where $\mathbb{Z}_{1,m} = \{1,\ldots, m\}$.
(For instance, computed as the (scaled) ...
