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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.

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Code for Generating Spectrum (MFCC) vs. Time Images

I am trying to do speech wake up (hot) word recognition by transforming it into an image recognition problem. The images are some kind of spectrum (MFCC) vs. time, made from a wave signal. I recall ...
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1answer
26 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 ...
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0answers
28 views

Functioning of Pre-processing blocks in image processing

Can anyone please explain that why do we need to preprocessing block and what is the importance of each block in preprocessing stage in image enhancement ?
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19 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 ...
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1answer
37 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 ...
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1answer
29 views

Entropy of an image with equalized histogram

Let's suppose we have an image and perform histogram equalization on it. Would the entropy of the resulting image be lower, higher or equal than the entropy of original image? At first I tought that ...
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2answers
46 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?
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0answers
15 views

What is the best way to overcome color mixing limitation?

I'm doing image processing using c++ and openCV to process color. Color mixing method (addition and subtract), when you try to do it in computer with RGB system, colors will have some value (0-255). ...
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1answer
26 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 ...
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0answers
13 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. ...
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0answers
28 views

Phase considerations in image filter design for precise noise removal (image in post)

I have images with systematic noise caused by the instrument in different subdomains of the image, and I'd like to design a filter to - on average - improve the quality of the images. Since the noise ...
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3answers
80 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 "...
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18 views

ECG image digitization [duplicate]

How can i digitize this ecg image using python ?
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1answer
61 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 ...
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0answers
36 views

How to calculate the scale factor for Laplacian of Gaussian

Trying to implement the LoG with different kernel size and sigma. Been reading this post: Introduction to IP : Laplacian of Gaussian? Which mention a scale factor of approx 482 for a 9x9 size kernel ...
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2answers
67 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 ...
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0answers
37 views

How to produce the Semantic Segmentation Dataset?

I am preparing my own synthetic data-set, to pre-train my deep learning model. I have produced images and there corresponding masks using some python scripts, but I am not able to find the way of ...
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1answer
66 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? ...
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0answers
21 views

Image brightness and contrast adjustment on stereo image pairs

I have a pair of stereo images captured with two different cameras. They differ in brightness and contrast as they were not captured with global shutter cameras. I need to apply semi global matching ...
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0answers
49 views

How to extract text from scene images?

I tried many methods for segmenting images like the example below ; but i obtained no efficient result can someone suggest me a good method for extracting text from complicated images like this ...
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1answer
40 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: ...
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0answers
24 views

How to properly filter an image in the frequency domain using matlab

my problem is the next: I´m starting to understand the world of image processing and I´ve been kind of bugged with the idea of filtering images in frequency domain. I have made a test programm in ...
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0answers
127 views

Using Ordered Dithering Given a non-monochrome palette

Good afternoon. I've been looking into image processing techniques to reduce the amount of color, and one of the ones I"ve come across is ordered dithering (Wiki). In the examples I've seen online, ...
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1answer
33 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 ...
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2answers
58 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 ...
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1answer
103 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 ...
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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}^...
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21 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 ...
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1answer
46 views

Algorithm/Code for finding surface shape of an image?

Is it possible to find the surface shape of an image as mentioned in the reference question ? If I find the unknowns of the equation , then what should be my next step in determining the shape of the ...
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1answer
529 views

10 bit pixels convert to RGB

I have a camera which is providing me raw, binary data with 10 bit data. It follows the Bayer pattern RGGB, and each pixel is saved using 16 bit chunks. I am able to demosaic the image almost ...
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0answers
25 views

correspondence problem in multiple views

I have a setup with $n$ cameras $\{P_i \}_{i=1}^n \in \mathbb{R}^{3\times4}$ and $m$ 3d points $\{X_j \}_{j=1}^m \in \mathbb{P}^3$. The 'ideal' set of 2d points for each camera can be defined as $\big\...
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0answers
34 views

Regarding compatibility of ISP's

I am working for an electric mobility startup and our aim is to produce electric cars with ADAS/autonomous-driving capabilities. Right now we are in the process of building a prototype. For meeting ...
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2answers
40 views

Creating derivative images, based on original, that can only be visually understood when stacked

I've been thinking about this for a while. What I have been trying to accomplish is a way of taking an image (png specifically, or any other format that allows transparency) and generating N ...
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4answers
129 views

How to see the amplitude of each frequency?

do you know software that exports spectrograms to images of 500x22000 pixels? all the spectrograms that I know show diffused frequencies and it does not look very good I just want to see the amplitude ...
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0answers
37 views

Best correlation technique in image processing

I want to find displacement between two images (one is the original image and the another one is the deformed version of that image). Can I do this by using correlation techniques? If so, then which ...
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20 views

computing auto correlation for some images

would you please help me how to compute auto correlation for some images (in the form of some 2D matrices)? for example, how can I compute auto correlation for these 3 matrices manually?
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0answers
14 views

sharpness in DCT domain image

How can we calculate the sharpness of Discrete Cosine Transform domain of an image?Is it worthy in image quality assessment?
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2answers
75 views

How to reconstruct an image from s-parameters in Matlab?

I have a set of data which is the s-parameter (s11), consisting of 2 columns ($1001 \times 2$). The first column represents the frequency and the second column is the magnitude in dB. I need to use ...
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41 views

How to obtain the relative position (coordinates) of SIFT feature from image center coordinates?

I have extracted SIFT features (keypoints and descriptors) of training set and saved in an inverted index form. My question is how can I calculate the coordinates of each visual features in an image ...
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2answers
300 views

Transform RGB image to *look like* Infrared

Context: I'm trying to improve a pose estimation model so that it works better when my camera is in Infrared mode. Unfortunately I only have RGB images to train on. I realize that you can't convert ...
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0answers
68 views

Shrink an image from 1250 dpi to 100 dpi and then zoom it back to 1250 dpi using bilinear interpolation?

I have an assignment as stated in the question but I am unable to understand what the question is really asking. Shouldn't the dpi only matter when we are printing an image on an actual hard copy ...
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1answer
78 views

Finding filaments in an image

I am at the moment working on images such as this one: What you see are filamentous structures / bundles. Other images coming from slightly different experiments could have more sparse / thick / ...
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0answers
28 views

Bitmap comparison bounded by limitations in human visual perception? [closed]

I need to do a pixel-for-pixel comparison between a 'candidate' image generated by a deep-neural-net against an 'ideal' image. Rather than just comparing RGB values, I'd like to do a comparison that ...
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1answer
47 views

What is difference between along the edge and across the edge

I am trying to implement a paper called structured tensor based image interpolation. In the paper I came across a concept called tangent direction and normal direction. What they mean is tangent ...
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2answers
332 views

How to calculate transfer rate and needed bandwidth

I have two questions: 1- If I want to transfer a photo via bluetooth, how should I find how long it takes to transfer? I mean the formula between the image size, bluetooth bandwidth and time. 2- If ...
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0answers
28 views

image processing : Segregating panel vs house like structure

I am working on a problem that involves segregating solar panel vs house. Both the house as well as panel are of same color. NOTE: There are two houses in the image. I am referring to the one which ...
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1answer
23 views

How to find derivative of an image along a radial direction with an arbitrary center of rotation?

I want to find the derivative of an image along a radial direction. For instance, in the image below I want to find the gradient at a point $P$ of the image, along the direction of the circumference ...
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2answers
291 views

What is Gamma correction - is my beginner's interpretation right?

I've started a course on image processing for beginners, and am trying to understand Gamma and Gamma Correction. Unfortunately, I seem to have come across conflicting explanations across multiple ...
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2answers
127 views

Why does gamma correction of image use two different definitions of gamma?

I've noticed that the gamma value used in level adjustment of Photoshop and Canvas is 'opposite' of gamma values defined in Wikipedia or MATLAB imadjust ...
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19 views

Adaptive Facial blurring

I got one problem related to facial blurring. The problem is Input: Image with facial (can be any location, not aligned, multiple faces) Know the bounding box: ellipse bounding box I would like ...