Questions tagged [image-processing]
The image-processing tag has no usage guidance.
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27 views
Speed of different access methods reading a picture
Suppose there is a cpu with a cache line of 64 Bytes. Now you need to access all the data of a 2D image stored in the main sequence of the line by pixel. The image size is 1024*1024, of which there ...
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1answer
34 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
96 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 ...
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0answers
24 views
How to convert a .tif file -with elevation encoded- to another image format?
I'm having .tif files that need to be converted to grayscale .jpg/.jpeg or .png. The grayscale denotes terrain height.
When opening a .tif file, only geographic information is visible, for example ...
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0answers
20 views
Fitting poly (N-)gon to non-square image
I have a list of non-empty pixels in an image, and I want, for a given N, to find an N-gon which contains the most of those empty pixels and the fewest empty pixels. How would I go about doing this?
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0answers
17 views
how feature detection benchmark ROC is constructed and what it is really mean?
How to construct ROC curve with the values of recall and 1-precision for benchmark dataset. What really a graph of ROC means that is how a curve is formed?
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0answers
42 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 ...
0
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1answer
43 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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0answers
41 views
What open source software can calculate Coons Patches from source images for use with SVG's new mesh gradient feature?
Version 0.92 of inkscape supports the proposed Mesh Gradients for SVG which is based on Coons Patches. I watched one of the demo videos on youtube and it occurred to me that the simple grid-based ...
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1answer
55 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 ...
2
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2answers
86 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
45 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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2answers
129 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 ...
4
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1answer
103 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....
1
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0answers
57 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
69 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
68 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
343 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 ...
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2answers
103 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, ...
2
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1answer
139 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, ...
3
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0answers
28 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 (...
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0answers
45 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 ...
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0answers
109 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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2answers
893 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 ...
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1answer
45 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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1answer
23 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 ...
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0answers
33 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 ...
4
votes
1answer
86 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
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2answers
75 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 ...
1
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1answer
58 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:
...
3
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1answer
151 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 ...
3
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1answer
85 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 "...
2
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1answer
242 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 ...
4
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2answers
301 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
152 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 ...
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1answer
215 views
Bilinear Interpolation
I am trying to implement bilinear interpolation as described in the paper Spatial Tranformer Networks by Jaderberg et. al (see link to paper). They describe bilinear interpolation in Equation 5 as:
$$...
2
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0answers
134 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 ...
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0answers
159 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 ...
2
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1answer
127 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 ...
1
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1answer
61 views
Appropriate filter steps for resolving a droplet pixel
I have a series of images obtained from a microscope as follows
I need to create a series of filters that would isolate the centre section on the yellow droplet.(This is highlighted by the bright ...
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0answers
53 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 ...
4
votes
1answer
45 views
can half of a picture be processed and viewed?
Lets say i have a picture. I send it to a server. While sending it to the server half way the upload gets canceled. Now the server has half or some of the picture. Now is there a way in which this ...
6
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1answer
479 views
Tone Mapping & Gamma Correction
I've been looking up this question on the internet for a while, and I haven't been very successful, so I decided I'll ask it here. Should I apply tone mapping before gamma correction, gamma correction ...
4
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0answers
62 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?
4
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1answer
88 views
Relationship between spatial frequency of an image and Aliasing
I was looking into measuring the amount of aliasing in an image. After reading through many papers and sites, I came to the conclusion that the best method to measure the amount of aliasing in an ...
4
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1answer
233 views
How can I remove aliasing in an image without introducing blur?
I am trying to reduce aliasing in an image using some filters. I tried the Gaussian variant of filters to remove the said high frequency patterns in the image, but I feel it's a bit too much of a blur....
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0answers
93 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 ...
7
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1answer
483 views
Seamless Textures
I understand how an artist would make seamless textures by hand, but how can a computer program automate that process? Software like PixPlant is capable of doing this, but I don't understand how it ...
5
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0answers
119 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 ...
