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.
418
questions
0
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1answer
13 views
Gender classification using Periocular Region
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
25 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
15 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
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2answers
26 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 ...
-1
votes
0answers
13 views
Autocorrelation of vector of images
I have a set of images (think a ball getting bigger and smaller). I want to assess the periodicity in this string of images (each data point in my signal is an image). How can I go about doing this in ...
0
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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
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0answers
8 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 ...
7
votes
5answers
410 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
21 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
35 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
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0answers
26 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
22 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
31 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
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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 ...
1
vote
1answer
55 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
94 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
35 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
223 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
52 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
24 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
17 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
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0answers
20 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
29 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
303 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
99 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
174 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
37 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
105 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
20 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
240 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
72 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 ...
1
vote
0answers
33 views
What should I know about Morphological processing [duplicate]
i'm studying my first year as technical student , and we are studying image processing, so last week we got delivered a topic to work on : Morphological processing /opening
, i'm trying to dig deeper ...
0
votes
1answer
59 views
How can I trace a path around an image consisting of only black and white lines?
I'm looking for a way to trace a closed curve (i.e. a long list of pixel values all connected by lines in between) that approximates a bitmap image of black and white lines.
The image starts out as ...
1
vote
0answers
32 views
“Image Processing” [closed]
I'm an Italian student. I'm studying Gnu Radio and I would like to upload a photo, can I upload it with "file image source" or other blocks?
I need to make FFT of an a image. -> image 2D
Thank you ...
0
votes
1answer
100 views
Edge detection in a crack pattern image
Here's an image of a cracked pattern. I wish to convert it to binary image where the continuous crack lines form the only discernible pixels. The main problems I am having in the lack of uniform ...
-2
votes
2answers
84 views
Image processing - Why is sum of values of a blurring filter = 1?
Usually, blurring filters have the sum of all the values in the filter matrix equal to $1$.
Why is it so?
1
vote
1answer
33 views
How many moments are needed for a discrete distributions
I am doing a project on imaging and I have a more general question about imaging.
In general we use the moments of the distribution of the object imaged, because the capture information about the ...
1
vote
0answers
17 views
Can an untilted perspective of an object be obtained from a 2D image of a tilted object using angular transformations?
I'm trying to make a height estimation algorithm that works in tandem with a bounding box object detector. The object detector can recognise the objects in images taken at pitch/yaw angular offsets.
...
1
vote
3answers
433 views
How to determine if a pixel is inside a contour?
I have following picture
which I extract the contour from. The contour looks like following
I am wondering, for any pixel in the image, how do I determine if it is inside the contour or not? Say "...
0
votes
1answer
87 views
Is this jumbled image due to difference between Matlab and Python slicing?
When I import an image from Matlab I get the following jumbled image
rather than the (224x224x3 RGB) image of a single elephant I expected
I write the image from Matlab as a binary file
...
1
vote
2answers
238 views
How can I remove flickering background in a video?
I have a black and white video taken with a high speed camera and I notice a background flickering coming from my LED light. The images alternate from dim to bright and it makes the videos quite ...
0
votes
1answer
222 views
why multiply grayscale images by 256
I am a newbie in image processing. in an open source code for convolution neural networks, the author is multiplying a gray scale image from MNIST dataset by 256. Please can any one tell me why?
...
0
votes
1answer
63 views
opencv otsu binarization not working
I tried to apply opencv OTSU binarization on the following image, but it generate a black image.
Here is the following python code:
...
1
vote
1answer
85 views
general n-dimensional name of Pixel and Voxel
In 2D images we call the smallest picture elements pixels, in 3D images we call them Voxels (for volume pixels).
I was wondering if there is a word that can denote them both (pixel and voxel), and ...
0
votes
2answers
62 views
What are some current algorithm(s) for finding if two images are copies of each other?
Could anyone enlighten me on what are the current best ways to detect if two images are the same (i.e. a copy or edited copy of each other)? What feature detection method do they use (SIFT, DWT, pixel ...
0
votes
1answer
346 views
SSIM(YUV) vs SSIM(Y): values very different
I'm seeing some weird results when trying to compare image qualities in a few different color spaces. Have a look at my graph:
I want to compare with another publication, which reported PSNR(YUV) and ...
0
votes
2answers
31 views
Is there a way to measure each pixel's content in an image somehow?
Is there a way to measure each pixel's content in an image somehow?
Like can I interpret each color as some kind of a single value, rather than a triplet?
Perhaps I can think of them as $\mathbb{R}^...
0
votes
0answers
28 views
Print Image from pixel data - Matlab
I have the pixel data of an image in a 1x256 vector where each cell represents a pixel of a 16x16 image. I have written the following code in Matlab but I am not getting what is expected as an output ...
