Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [blur]

The tag has no usage guidance.

1
vote
2answers
58 views

How to approximate gaussian kernel for image blur

From wiki, a $3 \times3$ gaussian kernel is approximated as: $$\frac{1}{16}\begin{bmatrix}1&2&1\\2&4&2\\1&2&1 \end{bmatrix}.$$ Applying this kernel in an image equals to ...
1
vote
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. ...
1
vote
1answer
700 views

blur detection using opencv

I'm writing a script to detect blur images using OpenCV by applying Laplacian filter and calculate the std but there is a problem the std for images that contain motion blur is very close to those ...
0
votes
1answer
312 views

Fastest Available Algorithm to Blur an Image (Low Pass Filter)

Iam working with a camera that produces ugly artifacts: by using ANY blur filter on the camera's output the visual quality improves drastically: The above image was created using OpenCV's cv::...
1
vote
1answer
290 views

Image zoom out using Gaussian blur and downsampling

I am trying to implement a simple zoom out algorithm using two steps: The image is blurred using gaussian convolution of standard deviation $0.8\sqrt{{\tt zoomfactor}^2-1}$ as we saw in class. The ...
0
votes
1answer
196 views

How to predict next image in a sequence, or predict the deblurring of an image?

I have 3 versions of an image at lower resolutions - 480p, 720p, and 1080p. Is it possible to use those 3 images to predict the next highest resolution image (the 4k image)? My first guess was that ...
2
votes
1answer
475 views

Edge map based on a Haar Wavelet Transform

I have been implementing the paper Blur Detection for Digital Images Using Wavelet Transform and was asking myself how the following formula could reconstruct the edges given a Haar Wavelet ...
6
votes
2answers
6k views

How to locally quantify the 'sharpness' of an image?

I am trying to quantify how much sharpness (or acutance) is in a picture which has some bokeh (out of focus background). I am using the Python scikit image for that. Here is my naive approach: ...
0
votes
0answers
186 views

Relationship between Blur convolution matrix and radius/intensity

Given a blur radius and an intensity, how do I get the matrix for Gaussian Blur or Blur to act on an image with a convolution filter? I need the algorithm or an explanation, but then I should write ...
3
votes
3answers
96 views

Why does an image get blurry beyond a limit of zooming?

As we have came cross a phenomenon where a picture get blurry and more blurry as we zoom in a image beyond a limit. Why does it happen?
1
vote
0answers
1k views

Measuring sharpness/contrast for autofocus

For the implementation of an auto-focus for the raspberry cam I need some measure of image sharpness. I used the following sample picture: The first approach was to compute the shannon entropy of the ...
0
votes
2answers
3k views

What is the difference between convolution filter, low-pass filter, and median filter?

Isn't blur filters, like median filter, a type of convolution filter? How does a low-pass filter relate to them? Why does this guy differentiate convolution filters here from blur filters here?
0
votes
2answers
3k views

Blending artifacts in OpenCV image stitching

I am using OpenCV to blend a set of pre-warped images. As input I have some 4-channel images (*.png or *.tif) from where I can extract a bgr image and an alpha mask with the region related to the ...
0
votes
1answer
636 views

How to make a 2D gaussian Blur terms?

I want to make a 2D gaussian Blur coeffients. Now I am making 1D gaussian Blur term as following. ...
1
vote
1answer
855 views

How Does Gaussian Blur Affect Image Variance

I am trying to find a way to analytically estimate how the noise (or variance in pixel values) will be affected for a zero-frequency image of random noise after applying a Gaussian blur. In more ...
2
votes
1answer
153 views

What is the most efficient way to perform Gaussian blurs for varying sizes of Gaussian kernels in an image?

I have detected corner points of images using Harris corner detector in GLSL and now, I intend on using Fast Retina Keypoint(FREAK) as keypoint descriptor to later match the keypoints between images. ...
0
votes
2answers
3k views

How to Calculate Gaussian Kernel for a Small Support Size?

How to calculate the values of Gaussian kernel? I think I understand the principle of it weighting the center pixel as the means, and those around it according to the $\sigma$ but what would each ...
9
votes
2answers
4k views

Isolate the non blurred part of foucsed image

I have an image taken by a mobile phone camera with focus on a part of it let say a face or whatever. I want to know -approximately- where is the focused area. For example, a bounding box around the ...
3
votes
2answers
13k views

Gaussian Blur In Matlab and Connection to Image Resolution

I am calling fspecial in matlab to create a Guassian blur of an image. For example, ...
15
votes
3answers
41k views

Gaussian Blur - Standard Deviation, Radius and Kernel Size

I've implemented a gaussian blur fragment shader in GLSL. I understand the main concepts behind all of it: convolution, separation of x and y using linearity, multiple passes to increase radius... I ...
1
vote
1answer
618 views

Gaussian Blur Detection

Let's say you have an original image and a version of the same image that may have been convoluted with a Gaussian blur. How could you demonstrate that the Gaussian blur has been applied and calculate ...
6
votes
1answer
808 views

Deblurring algorithm to precede thresholding - speed over accuracy

I'm writing an app that recognizes Sudoku puzzles from a camera input. I'd like to remove camera blur from the images to improve recognition. Here is an example image: Since I'm processing a ...
3
votes
1answer
1k views

Blurring Non-Uniform Areas

I have an image with arbitrary area (the boundary is shown in gray): I would like to blur just the image within boundaries. Ordinary blur causes the background proliferating to image and vice versa. ...
5
votes
1answer
1k views

Degraded image: Wiener Filter vs Wiener deconvolution

I am studying methods for recovering images (that has been blurred and noised). Can someone explain the difference between: http://en.wikipedia.org/wiki/Wiener_deconvolution http://en.wikipedia.org/...
7
votes
1answer
996 views

Deconvolution - Richardson Lucy vs Wiener Filter

I am studying some deconvolution techinques (to remove motion blur) like: Richardson-Lucy Wiener Are there any pros/cons of using one versus another? For example which are the pros/cons of ...
22
votes
3answers
12k views

How do I remove motion blur?

Is there a generically accepted method of removing motion blur from an image. For a simple case, we can assume that motion happens in a straight line. I assume that it's a two part process composed of ...