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11 votes
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Detect in-focus regions of an image

it is quite easy to measure the local max frequency in an image (at least as a low resolution mask, with some regularization). Several papers of the MIT graphics group have been around detecting and ...
Fabrice NEYRET's user avatar
9 votes
Accepted

Tweaking a glow shader to make it look better

Sigma and kernel size of Gaussian filter Regarding how to choose the sigma and the kernel size (pixels) of the Gaussian: you set the sigma based on how wide of a blur you want (judging it visually) ...
Nathan Reed's user avatar
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7 votes
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Applying correct light physics to gaussian blur formulas for glow

Yes, your theory is correct. A gamma-correct blur entails converting the input pixels to linear color space, performing the blur weighting and accumulation in that space, and then converting back to ...
Nathan Reed's user avatar
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7 votes

Blur with alpha transparency

Two suggestions: If your data is from an image you are displaying on a standard monitor, the chances are it is (or you are implicitly assuming that it's) in sRGB format. This means that the colour ...
Simon F's user avatar
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5 votes
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Bokeh from depth map

The blog post that you talked about, is not about generating bokeh for a computer generated image. It is instead about generating a believable depth of field effect from an image captured by a ...
bram0101's user avatar
  • 1,595
3 votes

Blurring image with RGB values without convolving it with a kernel

Blurring an image depends on being able to read from the image. If you don’t have access to the pixel data, or external information about the image contents (e.g. average hue / luminance), there’s no ...
Noah Witherspoon's user avatar
3 votes
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Origin of blurring and colour distortion in monochrome diagrams

This looks like JPEG artefacts so I guess the image went through a JPEG compression step at one stage and that permanently introduced noise into the image. The red channel is blurred stronger because ...
PaulHK's user avatar
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3 votes
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Deriving blur from real optical formulae

First we can calculate the physical diameter of CoC in the image plane, given the lens parameters. This equation is from Wikipedia – Circle of confusion: $$ c = {|S_2 - S_1| \over S_2} {f^2 \over N(...
Nathan Reed's user avatar
  • 24.8k
2 votes

Modulo vs Scaling vs Capping when performing filters

While clamping or saturating may be the most common way of handling this situation, it's usually not the best. (But wrapping/modulus is one of the worst.) Another way of handling it is to either ...
user1118321's user avatar
  • 3,401
2 votes
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Modulo vs Scaling vs Capping when performing filters

When doing a filter operation such as a blur, in many cases the filter itself will be normalized so its values sum to 1.0, precisely to avoid this problem. In cases where out-of-range outputs do need ...
Nathan Reed's user avatar
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2 votes
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Questions about Blur effect

If I blur the whole image and apply the result on the sphere, the white background will bleed onto the sphere shape and I want to avoid that. I also don't want that the blue (3) and yellow (4) sphere ...
Tare's user avatar
  • 1,541
2 votes
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Is it better to blur the input or output of an edge detection shader for noise reduction?

Standard blur removes high frequency content from the signal, whereas edge detection usually look into high frequency to detect edges. Be careful on how much blurring to apply to ensure that you don't ...
Soravux's user avatar
  • 371
1 vote

Blurring image with RGB values without convolving it with a kernel

While you can't do what you're asking, you might be able to use a compromise. It turns out that all human skin tones have the same hue. They vary only in saturation and brightness. You can see this on ...
user1118321's user avatar
  • 3,401
1 vote

Blurring image with RGB values without convolving it with a kernel

Since you know vaguely what the pixels you're covering up look like (they are faces), your best bet to get the appearance of a blur is to really blur an image of a face in a standard image editing ...
Dan Hulme's user avatar
  • 6,700
1 vote

gaussFactorForOffset cannot call a non-function how to fixed this code?

It would be helpful if you posted some more information about what you're trying to do (rather than problem links) and some screenshots of what is actually happening. Being here I basically see "My ...
Tare's user avatar
  • 1,541

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