Questions tagged [image-processing]

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36 questions with no upvoted or accepted answers
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11
votes
0answers
298 views

Why does increasing simplex noise dimension wash it out?

I just tried using this approach to create a tiling 2d simplex noise function with Gustavson's java implementation. The result tiled, but the texture seemed muddy / washed out. I decided to compare ...
5
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0answers
143 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 ...
4
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0answers
73 views

Slope Based Texturing

On the main page for Allegorithmic's Bitmap2Material, it mentions that the software uses a Slope Based approach over a Luminance Based approach. What exactly does this mean?
3
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0answers
70 views

How to separate, modulate, and reassemble spatial frequencies?

Background I am trying to create a node in Blender that would allow me to do what you would do with an audio equalizer but on the spatial frequencies of an image: A sort of panel with eight ...
3
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0answers
43 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 (...
3
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0answers
151 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 ...
3
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0answers
86 views

Recreating a font from a low-quality printout

I have a JPEG file with a 200 dpi scan of a sample printout from a badly maintained old drum printer. I was able to segment it and to collect all instances of each letter together, for example I ...
2
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0answers
48 views

How to project an image on spherical surface with least possible distortion

I did not know where to ask, I will try it here. I work in a local planetarium and I wonder if it is possible to edit an image in such way, that when projected on spherical cupola (diameter 8 m), it ...
2
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0answers
137 views

Making an approximately constant color or brightness image

I've been working on implementing the technique from the paper "Designing look-and-feel using generalized crosshatching" which can be found at: http://dl.acm.org/citation.cfm?id=3085054 The paper ...
2
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0answers
113 views

How to merge multiple exr into a single multilayer exr?

Are there some tools or softwares to merge multiple exr into a single multilayer exr? I only find a tool to split a multilayer exr into multiple exr. And it seems that Blender, Mitsuba, Darktable ...
2
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0answers
442 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 ...
2
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0answers
100 views

SIFT Feature Extraction

I am trying to implement the SIFT feature extraction algorithm. I have a few questions which are not very clear from the paper: When interpolating the extrema with 2nd order functions, do we upscale ...
2
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0answers
74 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 ...
2
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0answers
365 views

Template matching subpixel accuracy

I use template matching to detect a specific pattern in image.The shift determined is very shaky. Currently I apply it to R,G,B channel separately and average the result to obtain float values.Please, ...
1
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0answers
30 views

Are there some methods of preventing tools like FotoForensics from detecting manipulations?

I am asking this question purely our of curiosity. I do not look for step-by-step tutorial on how to manipulate a photo and making sure that it will be hard to detect it. I was wondering, because ...
1
vote
1answer
45 views

How to translate the center of an equirectangular projection?

I'm trying to perfectly align two or more equirectangular photos of the same place taken from slightly different positions. Using an example provided by openMVG I managed to get the relative position ...
1
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0answers
58 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 ...
1
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0answers
47 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 ...
1
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0answers
77 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 ...
1
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0answers
70 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 ...
1
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0answers
37 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 ...
1
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0answers
353 views

Getting improper undistorted images for stereo calibration

I am trying to calibrate stereocamera using left and right chessboard images available at github.com->opencv/opencv/tree/master/samples/data After undistorting them, left images seem to look right ...
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0answers
113 views

Finding Segments in Continuous line

I'm trying to break a continuous line segment into multiple, straight segments. I've tried using the Hough transform but have found it unreliable for getting the line segments I'm looking for and ...
1
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0answers
195 views

Octave matrix to image pixels too small (do not have 1 pixel per integer)

I am working on a project which plots points over a checkerboard (representing seats for people). I would like each pixel in the image to represent each integer matrix entry. After updating my ...
1
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0answers
139 views

image warping, given the rotations/translations

in OpenCV there is functions to warp any 2D image using a homography matrix (3x3), e.g. cv2.warpPerspective. These matrices are generally constructed using point ...
1
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0answers
168 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 ...
1
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0answers
83 views

Image cleaning - removing all regular shapes ( circles, squares, text, icons etc. )

I'd like an automatic method to clean images. I've been looking at the GIMP, and its command line (cli) interface, in scheme / lisp. It looks very promising, but I'm a complete novice, so I'd be ...
1
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0answers
50 views

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 ...
1
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0answers
74 views

How to enhance scans of golden emboss?

I am looking for smooth way to enhance scans of golden emboss on. For now it takes sometimes hours to select out the golden part and then manipulate into suitable color. But I hope to learn some more ...
0
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0answers
44 views

Which method does the painting software use to deform the image so fast?

I tried to make my own painting software. I used OpenCV in my job so I use openCV here. I want to make a image deformation function like the following : use mouse click on GUI to deform the image. I ...
0
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0answers
16 views

How can you use a rectangular object in an image and use its edges as a new coordinate system?

As a quality inspection vision application, we have images of printed circuit boards. The PCBs are rectangular in shape and the distance from the camera to the PCB is fixed. The relative location of ...
0
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0answers
19 views

Export images in sketchup models

I built a model on Sketchup and imported png images in it to fill some faces. At first time, I tried to fill with a texture pointing to the desired image but it wasn't centered. Then when I export my ...
0
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0answers
40 views

How do I represent the grid patterns of the image in the included figure with a DITHER MATRIX?

The problem statement is: "Represent the grid patterns in [the the figure linked below] with a dither matrix." The figure is: https://www.docdroid.net/d90WXko/figure.pdf Apparently, according to the ...
0
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0answers
20 views

Open source tools for extracting hi-res images from video

I found recently an article in which they describe a technique to extract high resolution images from a standard quality videos. The technique exploits the fact that in a typical video the camera ...
0
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0answers
96 views

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 ...
0
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0answers
47 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 ...