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.
433
questions
2
votes
2answers
35 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
44 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
19 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 ...
2
votes
1answer
114 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 ...
0
votes
1answer
17 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
36 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
14 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
61 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
23 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
73 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
13 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 ...
0
votes
2answers
16 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 ...
1
vote
1answer
48 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
10 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) ...
0
votes
0answers
25 views
Deriving transformation from input and output images
I will preface this by saying that my undergrad signal processing course is very far back...
Context:
I am comparing images of global illumination (GI) passes. I want to be able to change the ...
2
votes
2answers
68 views
Digital Image Processing Textbook with Specific Topics
I am looking for a Digital Image Processing and analysis textbook, but there are specific topics that I would like the book to cover. Among other topics, I would like it to include a discussion of:
(...
0
votes
1answer
230 views
How to remove striped noise from this image. Which filter or algorithm use better?
I need to process a gray scale image. The task is to remove the stripes, which constitute some noise.
I have next origin image:
This image received many channels ADC(Y) in moment of time (Xn) from ...
0
votes
1answer
20 views
Gender classification using Periocular Region [closed]
I have a dataset of the periocular region, I have images of the male and female periocular region but they are only labeled as left and right periocular region, Folder is a mixture of male and female ...
0
votes
1answer
112 views
How do I measure the amount of information within an image?
I'm trying to find some information threshold that is required for performing detection of objects in images. However, I'm not sure how exactly to quantify the amount of information contained within ...
1
vote
2answers
35 views
Image downsampling with Haar DWT?
How can the resolution of an image in matlab be reduced by using 2D haar wavelet by downsampling-decimation? Is there any predefined code or tool within wavemenu? thanks in advance
0
votes
2answers
34 views
Camera image pixel structure origin
I am using machine vision for industry task with opencv. I have images from a camera monitoring the process. The detailed look at the small part of the image follows:
Enlarged:
In the detail, it ...
0
votes
0answers
9 views
How to warp and enlarge the center of an image?
I am trying to smoothly enlarge the center part of an image. The Skimage code that I use need an inverse map that specifies location of input pixels that will occur at the output pixel location.
If I ...
0
votes
0answers
10 views
Adjustments to get better result appyling hough circles
I have the aboveimage and wanted to detect circles spread around the image. I can detect the circles in the middle through hough circles but it does not work out for the left-most circles which exists ...
8
votes
5answers
446 views
Auto Detection of Rotation Angle on Arbitrary Image with Orthogonal Features
I have a task at hand where I need to detect angle of an image like the following sample (part of microchip photograph). The image does contain orthogonal features, but they could have different size, ...
0
votes
1answer
23 views
Why does the Y component in YCbCr represent luma/intensity?
As far as I know, the RGB to YCbCr conversion is just a linear transformation, yet the Y channel successfully captures the intensity value of each pixel. How?
In other words, where do the following ...
2
votes
0answers
82 views
How do 2D DCT basis functions interact to produce 8x8 JPEG tiles?
This section is a bit of an intro. If you want to skip directly to where the problem is explicitly outlined, skip to the bottom of this post. Please note that I'm not hip with mathematical lingo, so ...
0
votes
0answers
34 views
Intuitive understanding of Fourier transform of images [duplicate]
I am trying to have an intuition about the Fourier transform of images
For example the image on the right is the Fourier transform of the image on the left,
my question is :
1)Why are the ...
0
votes
0answers
26 views
Elimination of image blurring using noise model restoration techniques
How can the blurring be eliminated from image using the noise model restoration process techniques?
To my knowledge the answer must be filter.If yes,then which filter is used?
0
votes
1answer
64 views
What is the difference between domain and range filtering?
In the context of image processing, I have heard the expressions "domain filtering" and "range filtering". What do these terms refer to? What is the difference between them?
0
votes
0answers
8 views
Why is correlation involved? - Axis Rescaling for a 2D axes - brightfield illumination microscopy of blood cells
for 1D axis rescaling, you use a FOV calculation
len_pixel=total_magnification * len_specimen_in_pixel
len_specimen_in_pixel=len_pixel/total_magnification
and then to get the axes rescaled, you do ...
0
votes
0answers
28 views
Texture model of Active appearence model
I am working in a face detection project and currently I am trying to understand Active Apperance Model.I have understood how Active Shape Model algorithm works which is the shape model of the AAM ...
2
votes
1answer
89 views
Are There Common Values of Standard Deviation for Gaussian Noise of an Image?
For example, it occurs to me that there might be a standard deviation value of Gaussian noise in which the human eye could no longer distinguish an object because the standard deviation is very high ...
2
votes
2answers
141 views
Is there a rule of thumb for zero padding in image processing?
I see there are a lot of answers on why zero padding is necessary and how it avoids wrapping around the sides of images. However is there a rule of thumb on how much padding will be good for the image ...
0
votes
1answer
80 views
How to detect the maximum resolvable spatial frequency of camera?
I am trying to calculate the minimum line pixel width that can be distinguished from noise as shown in the camera test chart in Figure 1 where the thinner lines on the left are getting more and more ...
1
vote
0answers
25 views
How does phase relate to motions in an image?
There is lots of research based on exaggerating motions by decomposing an image into complex sub-bands using pyramid representations such as the complex steerable pyramid and manipulating phase ...
0
votes
0answers
352 views
Recover Audio from Spectrogram Image
I have applied transformation(Constant Q Transformation) to my audio time domain signal, this gives me Frequency vs Time representation. Now, the CQT values consists of complex values(84*260), but ...
0
votes
1answer
59 views
Why does White Noise in images imply noise in adjacent pixels are independent?
My professor said in the class that for "Additive White noise, the noise in pixels adjacent to each other are independent". How?
This is what I have got so far: White noise implies that PSD (Power ...
0
votes
0answers
25 views
Edge detection for bio-film filaments
I have this image of bio-film filaments growing in a matrix and would like to extract just the filaments from the image to calculate the angle at which they are growing. What techniques would be best ...
1
vote
1answer
20 views
Feature normalization (scaling) for Hyperspectral images
have been straggling with the concept of feature normalization for the hyperspectral images. Respect to my problem I have attached a picture of my problem which clearly stands the issue which I have.
0
votes
0answers
23 views
Filter a picture by its color spectrum
I want to split an image in half and remove all colors from one half which aren't present in the other half. I already converted the image from RGB to YCBCR but I'm not sure (from a theoretical ...
0
votes
1answer
33 views
What principles to use, in order to create field that will be read by OCR?
I currently have an invoice, where some numbers are written by hand, and I would need to read them automatically.
My past experience is that people who write numbers will them write in so many ...
2
votes
1answer
627 views
Performing DFT twice on an image. Why am I getting an inverted image? [duplicate]
I was asked to perform DFT on an image twice as a part of my school assignment. Why am I getting a blurry inverted image when I perform DFT on an image twice? Sorry, I'm new to image processing and ...
0
votes
0answers
208 views
Multifractal analysis of an image using wavelets
I want to measure the fractal character of images using a wavelet approach (if possible) in python. (E.g., maybe things like roughness, anisotropy, or just the fractal dimension - perhaps just ...
2
votes
0answers
309 views
How do piecewise affine transformation work?
How can piecewise affine transform be used to warp an arbitrary collection of input landmark coordinates to a corresponding set of base coordinates?
Can anyone give any physical examples, the book I ...
1
vote
1answer
40 views
Zoom an image with respect to a given image
I posted this question in stack overflow, but I think it is more appropriate here:
I have a reference image - 'image_01.png' of size 200x200 and resolution 72 px/in.
I have another image 'image_02....
-1
votes
1answer
180 views
How to increase the sharpness of the image using convolution matrix?
I am using 3 X 3 convolution matrix to obtain an sharpness image.
But the output result obtain from the above matrix is not much sharpen image.
How to increase the sharpness of the image ?
Ya i am ...
-1
votes
1answer
37 views
When does a color channel such as RGB carry more info than a grayscale channel or image?
Typically a gray-scale image gives us more information about an image in terms of a signal processing problem. But when does a color channel carry more info than a gray-scale channel?
I understand ...
1
vote
2answers
552 views
Is It Possible to Reconstruct the Original Image from Laplacian Pyramid?
In our computer vision course, my professor said we can reconstruct the original image from the Laplacian pyramid. It just feels to me that information is lost after doing subsampling and upsampling.
...
0
votes
1answer
136 views
Brightness equalization between different images
I am dealing with a proprietary whole slide image format from 3DHistech, namely MRXS. This image is produced by scanning a glass slide biopsy. The scanner takes pictures at certain positions which ...
