Questions tagged [filtering]

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OpenGL texelFetch causes black stripes

THE SHORT VERSION In my fragment shader I'm reading (using texelFetch) multiple times the same texel from a texture (created by another fragment shader) and write it to the output render buffer. ...
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2 votes
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685 views

how to overcome tracking jitter

I'm working with a object tracking project. Steps: Preprocessing the image and achieve some candidates regions of interest. For each region, test if it is the target by ORB/BF. After the target ...
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Image Laplacian incomprehension

I am reading and trying to implement a research paper. It uses openGL to define which part of an image to use in order to reconstitute a big image composited of several images. In order to do so, I ...
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1 vote
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53 views

What denoising filter gives highest quality for indirect light image?

Some background of my scenario: I have two images of indirect radiance, both are from an animation. I will reproject an pixel from the previous frame to current frame, and I want to do comparisons ...
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1 vote
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391 views

What is the difference between post-/pre- sampling, aliasing, filtering and processing?

What is the difference between post-/pre- sampling, aliasing, filtering and processing? How do the terms post-/pre-aliasing, post-/pre-processing, post-/pre-sampling and post-/pre-filtering relate to ...
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Image contribution function and reconstruction using filters

So I've been reading Physicall Based Rendering which in section 16.4.3 defines the "image contribution function" to be the following $$I_j = \int_\Omega h_j(X)L(X)d\Omega$$ where the variables are ...
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Why don't discretization errors occur with compute-shaded kernel filters?

An efficient compute-shaded image filter would be emitted with (screenX / [kernel width], screenY / [kernel height], 1) groups and one kernel in each group, allowing texels to pass into groupshared ...
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Why does this edge detect show different results for the same color combinations?

I'm researching highlighting accessible color contrast via filter operations. I have a test screenshot of SRGB hex values compared with WCAG's official contrast algorithm: I converted it to its ...
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Removing a darkened caption with text on it in an image

Alright so I'm a complete n00b at image processing so forgive me if my question sounds vague. I'll try to supplement it with what I have learnt until now and also a couple of images. See the caption ...
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GLSL texture() vs textureLOD causing odd texture filtering

I've got a fragment shader sampling an environment texture for world reflections, and in testing, there seems to be a major difference in the result for texture() ...
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How to retrieve RGBA mask used to transform image1 into image2

Let image1 be: And RGBA mask be: (45, 78, 251, 102) Apply mask on top of ...
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85 views

Relation between camera sensor responsivity and image reconstruction filter associated with a pixel

Let $W_{\text e}$ denote the camera sensor responsivity (i.e. importance) and $h_j$ and $W_{\text e}^{(j)}$ denote the image reconstruction filter and sensor response associated with the $j$th pixel, ...
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Convolution of multiple gaussian filters with different sizes

What is the size of the final filter after implement convolution of multiple gaussian filters with different sizes?
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193 views

Properties of the image reconstruction filter in rendering

Let $f$ denote the measurement contribution function for paths of length $k\in\mathbb N$, i.e. $$f(x)=g(x_0\leftrightarrow x_1)W_{\text e}(x_1\to x_0)t_k(x_0,\ldots,x_k)L_{\text e}(x_k\to x_{k-1}),$$ ...
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  • 163
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Lanczos filter implementation issue

I tried to follow Nathan Reed post Antialiasing: To Splat Or Not to implement splat method. The image I am getting thorugh the Lanczos filter is very different than Nathan. I do not understand where ...
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Baked anisotropic filtering using spherical harmonics

I want to learn is it good or bad idea. Let's assume video RAM is not a problem. For source texture create a texture of texels: spherical functions. Spherical functions defined by small arrays of ...
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YUV (NV12) Chroma subsampling while converting from RGB image

I convert RGB input to YUV 420 semi-planar output using compute shader.Luma plane is straightforward as it maps 1:1 with RGB dimensions. As we know, NV12 packs Cb and Cr into one plane, which means ...
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