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48 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?
25 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 ...
65 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?
408 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 ...
73 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. ...
49 views

How will a 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 ...
78 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. ...
96 views

How to calculate Gaussian kernel for a small pixel 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 ...
860 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 ...
8k 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, ...
13k 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 ...
264 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 ...
580 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 ...
289 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 ...
857 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/...