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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.

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21 views

What metric can I use to give results from a computer vision application?

My application uses different light sources to visualize some patterns but these can only be observed on backlight. Some of these sources are the sun at noon, sun at dawn, at dusk, etc., incandescent ...
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0answers
15 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 ...
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63 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 ...
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1answer
38 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 ...
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0answers
10 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 ...
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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.
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0answers
16 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 ...
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1answer
23 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 ...
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1answer
41 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 ...
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0answers
27 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 ...
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0answers
33 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 ...
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1answer
34 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....
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1answer
41 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 ...
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1answer
17 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 ...
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2answers
62 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. ...
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1answer
38 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 ...
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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 ...
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1answer
31 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
29 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
60 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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2answers
55 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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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
15 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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3answers
216 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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1answer
73 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
71 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
139 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
41 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
126 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
50 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
46 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
43 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
245 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
52 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
61 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
200 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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0answers
25 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
65 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
902 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
32 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
37 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
41 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
160 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
42 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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0answers
39 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
18 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
116 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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0answers
52 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 ...