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Questions tagged [image-processing]

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38 views

Prefered gpu for deep learning

Im planning to buy a custom build pc for computer vision because I want to make a career switch in it. So Im still confused about the choice of gpu. Should I go with nvdia(cuda) or amd(opencl)? Also ...
1
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0answers
48 views

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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1answer
24 views

Can you generate your own HDRI maps without using photos?

For example, preparing a scene in Maya using standard lights and rendering out a panorama? Could they also be made from scratch in photoshop using 32bit color? Is there a reason why people don’t ...
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0answers
25 views

Using Hough Transform to detect lines in an image

I am using hough transform on the following image after canny edge detection ...
3
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1answer
65 views

Adding noise to gradient

I found this picture When you zoom in to any part of the image, the background looks a bit noisy/grainy. See pixels around "violent violet" label: I'm trying to understand how to achieve the same ...
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1answer
49 views

Convert RGB image to YUV420 using a hlsl shader

I am new to shaders and I need to convert efficiently an RGB image to YUV420. I can convert the RGB image to YUV420 with a simple c++ program that uses the ...
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0answers
35 views

what is the limit of Triangulation Matting?

I am studying triangulation matting in computer graphic. It seems very simple but very cool to identify the foregrouand and background. However, I didn't find what's the limit of it. Besides the ...
4
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1answer
58 views

How to shift color values of a single RGB channel

I’m a weaver and textile maker with no prior coding or programming experience. In researching and reading through posts on this and other message boards, I was able to find a lot of useful information,...
2
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2answers
169 views

How to generate the stereographic projection of a 3D model

Given a 3D model, is there a way to stereographically project it to a 2D image? In particular, I would only need a little more than half the model (the lower half) to be mapped to the plane (mapping ...
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1answer
46 views

Resolution issue of generating a PNG icon for macOS menu bar

Wonder if anyone has experienced this. When generating png image icons for macos. its recommended at 19x19 pixels. However, based on that, the icon (shield) that is generated is pixellated compared ...
1
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1answer
37 views

How to blend a segment of an image with another image

I want to put a segment of an image to another image. But to make it realistic I applied poisson blending. But the output is not good at all. Output without poisson blending. The kid was cropped ...
2
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2answers
103 views

Calculate the average color of an image

I want to calculate the average color+opacity of an image. First I thought about just averaging all ARGB values component-wise, but this got really dark on images with a lot of transparency. I also ...
2
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1answer
131 views

What is a common approach to smooth structures in textures?

I have a screen-aligned texture resulting from multiple rendering passes. It looks about this: I want the edges to appear smoother than they do now (but still keep their characteristic shape). When ...
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0answers
45 views

How to ensure that the raytrcing coordinate system is teh same as the projection one?

I have 2 shading models right now, one is using voxels the other one is the standard projection absed renderization method. Putting them side by side I have noticed that no matter what I do one is ...
2
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1answer
318 views

How can I combine two filter kernels for image processing to create a single kernel?

Is it possible to create a single kernel which can help us to perform an 2 step image processing? For example, I want to first perform a median filter on my image to remove salt and pepper noise and ...
0
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1answer
57 views

Difference between Cropping, Scaling, Resizing & Changing Aspect Ration of an Image?

I've got a new task related to image processing in a website. I am too confused in understanding different terms used with sizing of an image. What is the difference between: Cropping an image ...
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2answers
81 views

How do I do batch conversion (preferably in MATLAB) from .gif images to .off or .stl mesh files? [closed]

I'd like to do a batch converison of 1400 .gif images into .off or .stl format files that'll be meshed images. Two sample .gif images are attached. How can I do this conversion possibly by a free ...
2
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0answers
73 views

Bilinear Transformation not working

I implemented this algorithm to fit given image to specified quadrilateral but the output is blank. I implemented it in C# as follows ...
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2answers
114 views

How to count aspect ratio of an image when you have dimensions?

What formula is for counting aspect ratio of the image as in this site: Aspect ratio calculator (ARC) | NinjaUnits For example: ...
1
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1answer
63 views

Quick 2-color quantization for small images

So I have a small (8x8 pixel) image in 24-bit color. I want to be able to (quickly) generate a color-quantized version of the image that only has two colors. One naive approach is to cluster a luma ...
6
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2answers
864 views

Pixel dispersion (dissolving) algorithms

This YouTube video of a flip-dot display (physical b/w pixels) shows the reverse of an effect that might be called dissolve or dispersion, i.e. a text emerges from noise by pixels moving in to form ...
4
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1answer
194 views

Creating depth map from a 2-D image?

My question is oriented towards the generation of depth map using any of the state of the art depth sensor. However, each of these method required the presence of an 3-D object in front of the sensor....
2
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2answers
93 views

What blend mode is this?

I asked this on Graphic Design but was unable to get any relevant help from them. I'm trying to reverse engineer a blending mode I've seen on a picture: This image was created by someone else ...
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0answers
46 views

Tanget plane of an image

My problem is about tangent plane. I have an image (m by n). I obtain surface normal vector using machine learning methods. Then i would like to obtain tangent plane for this surface normal. To ...
2
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1answer
162 views

Histogram of image intensities

I want to create a histogram of intensities 0.1, 0.2, .... 0.9, 1, from an image rendered using OpenGL and C++. How can I do this? Can I access the pixel intensities in the framebuffer somehow? Also, ...
5
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2answers
183 views

reducing image size increases file size?

When I download this image: then its total size is 341,0 kB. The image has a width of 2880 pixels and height of 1100 pixel and 1 X/Y resolution pixel/in. I opened the image with gimp and pressed ...
4
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0answers
129 views

Sinc interpolation and Ideal reconstruction example

I am trying to apply sinc interpolation on this data set. The patches in the left image is a snapshot of AutoCAD 3d faces. Lux values are calculated for centre of each patch that are in 0.3m x 0.3m ...
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0answers
62 views

Image Processing: Photogrammetry [closed]

I am new to image processing but I am currently exploring myself in 3D reconstruction during my leisure time. I have decided to use openCV (eg. edge detection, possible?) in C++., maybe with a little ...
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0answers
74 views

Ray Tracer Shadowing

So I'm working on an assignment where we have to design a simple ray tracer. The program has two objects that it can use, sphere and cube. It can render the cube and spheres, it also does shading on ...
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1answer
103 views

why not use hash function image instead of jpeg?

Why don't we just use an hash function to reduce the size of an bitmap,rgb raw image?isn't it more efficient of storage data and it produces lossless image after being decoded?The decoder is also very ...
2
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1answer
556 views

Passing parameters in Metal Compute Kernel using Swift 4

On the CPU side, I have a structure I want to pass to the compute kernel: ...
0
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1answer
47 views

How does image resolution change(process involved in calculation), when a screen on phone is rotated?

What is the process involved in calculating the resolution of image to be displayed when the screen of my phone(android) is rotated? My screen resolution is 1920x1080. It displays some videos only in ...
1
vote
2answers
107 views

Can I get numeric data from a color map?

In my class I often need to work with color map images. I would show the image and try to make inferences/observations about different subjects. Often times I need to actually quantify some aspects, ...
3
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0answers
32 views

Sub-pixel image registration using phase

Currently I'm trying to reproduce the result by the academic papers Sub-pixel Shift Estimation of Image based on the Least Squares Approximation in Phase Region by Fujimoto, Fujisawa and Ikehara (...
1
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1answer
102 views

How to generate a 2d histogram?

I'm playing around with volume rendering and looking into multi dimensional transfer functions. I keep seeing images like this for 2d transfer functions: I've read numerous papers and articles but ...
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0answers
56 views

How to make Convolved Diffuse and Specular image in C#

I am trying to take either a HDR panoramic or HDR cubeMap and from that create a Lambert Irradiance environment map and a Cook-Torrence Specular environment map. I am stuck at the proper ...
8
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2answers
931 views

What's a proper way to clamp dither noise?

When reducing color depth and dithering with a 2 bit noise (with n=]0.5,1.5[ and output=floor(input*(2^bits-1) + n)), the ends of the value range (inputs 0.0 and 1.0) are noisy. It would be desirable ...
3
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1answer
228 views

Why is the line from the camera to vanishing point parallel to the other parallel lines?

When trying to find the vanishing point of an image, why is it that the vector from the center of the camera to the vanishing point is parallel to the parallel lines of the image? What's the ...
1
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1answer
44 views

Matlab scatter hotmap [closed]

I have two columns of data, x(angle) and y(distance), they are my experiment results(figure 1). How can I use these results to make a ‘hotmap diagram’ by matlab? The z axis is the density value of xy ...
1
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1answer
52 views

How to plot an input signal in image?

Given an input signal(ex. sine) how can one go about plotting an image like below ones(the stripped black and white image)? The images are from these slides on image processing. Or this one:
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0answers
35 views

3D reconstruction using 2D matched points

I have 2 images, called left and right images. I have some matched points $[c_l,r_l]$ and $[c_r,r_r]$ in both of them (these points are in pixel coordinates). For a 3D point in the real world, they ...
3
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1answer
86 views

How would I convert a picture of a slanted surface into a straight one? [duplicate]

Suppose I took a picture of a whiteboard at an angle. If I could detect where the corners of the whiteboard are, what algorithms and linear projections could I use to convert this slanted view into a "...
4
votes
1answer
109 views

Why does an affine transform work only on three of the corners?

I am trying to use a linear transformation to straighten out the camera angle on this image: In other words, I want to transform the image into a head-on view of the whiteboard. I applied an affine ...
1
vote
1answer
59 views

Extracting the green-screen region borders

Given a png image with an unknown number of green colored (rgba=0, 65535, 0, 65535) regions 1- How can I find and put the border points of only the separate green boxes to an array like: ...
39
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4answers
25k views

How is Gaussian Blur Implemented?

I've read that blur is done in real time graphics by doing it on one axis and then the other. I've done a bit of convolution in 1D in the past but I am not super comfortable with it, nor know what to ...
1
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0answers
163 views

Feature detection for embedded platform OpenCV

I'm trying to do object recognition in an embedded environment, and for this I'm using Raspberry Pi (Specifically version 2). I'm using OpenCV Library and as of now I'm using feature detection ...
5
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0answers
127 views

CrazyBump Shape Recognition

I've recently been using CrazyBump, and I think I'm starting to understand how it works. But I'm confused about what it calls Shape Recognition. According to this website, that feature attempts to add ...
2
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0answers
350 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 ...
4
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2answers
340 views

Making low discrepancy sequence noise textures, not LDS sample positions

When making sampling locations, there is a lot of information out there on how to do white noise sampling, uniform sampling, uniform+jittered sampling, low discrepancy sequence sampling (eg halton) ...
4
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1answer
172 views

Was Evans & Sutherland CT5 really created in 1981?

A few days ago I found a video on Twitter showing the Evans & Sutherland CT5 Flight Simulator system. It was labeled as 1981 footage and looked really amazing. The first time I saw similar 3D ...