Questions tagged [image-processing]

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How Can I convert Grayscale values of an image?

I am trying to get the following image to a certain grayscale value I want the spiral to have a grayscale of 120 and everything else to have a grayscale value of 255. What can I do?
Henry Evans's user avatar
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How to extract points corresponding to faces from cube map projection (CMP) of panorama from point cloud data

I am working with the standford2d3d dataset http://buildingparser.stanford.edu/dataset.html which contains panoramas of various scenes and a .mat file of the point cloud information of all the scenes. ...
Miguel's user avatar
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What the diffrence between BC7_QUICK and BC7_USE_3SUBSETS compression flags in DirectXtex lib?

At the beginning I thought they were like Fast and Fine compression of Photoshop's Intel texture tools, but I later found the tool uses a different compressor called Intel's ISPCTextureCompressor, So ...
ahmed moussa's user avatar
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what is the math behind contrast&brightness adjustmentlayer in photoshop?

I have figure out the math with use legacy checked. but I don't know what is the math ps use with use legacy unchecked.
Celebrimbor's user avatar
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1 answer
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How do I normalize all pixel values such that all pixel values are 'pulled towards' the mean?

Originally asked in Graphic Design site here (but I don't know how to 'move' a question to another site) Credit to this guy: Python Tutorials for Digital Humanities - I followed a lot of his ideas, ...
skeetastax's user avatar
5 votes
1 answer
119 views

Screen space line anti aliasing

I need to solve the following problem: do some anti-aliasing onto an image that contains rasterized "lines". I have some post-processing effects that output super-thin (~1px) features such ...
leone ruggiero's user avatar
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0 answers
56 views

JPEG Corrupted file fixing

I had an old, broken hard disk containing a lot of JPEG files. I took that hard to an information recovery company. The company was able to extract part of the files well, But there are many others ...
Abdulrahman's user avatar
2 votes
1 answer
122 views

How can I get an Irradiance or power value from RGB?

is there a way to output the power in watts from an R, G and B value? I know there are many formulae to get perceived brightness but is there one to get an objective amount (relative or otherwise)? ...
Dom DJ's user avatar
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Why does my screen flicker when scrolling the image below?

I'm not sure if this is the correct place to ask this, but does anyone here know why my screen flickers (not in a broken kind of way) when scrolling on this image from Claude Mellan
LoyalPotato's user avatar
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44 views

how to fix this strange effect when editing image?

G'day, I have this strange effect when editing my image. It seems to happen a lot on photos with the sky in it, but in the CR2 file it doesn't show, only when i open it in the software i am using does ...
38Airborne's user avatar
4 votes
2 answers
124 views

How to decode a JPEG file which is not fully loaded yet?

I see web browsers doing this all the time when the internet connection is slow, loading the JPEG images almost line by line from top to bottom. How is this done in practice? I experimented with ...
jhk999's user avatar
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How to find the nearest palette color when dithering in RGB

I maintain an image dithering library and command line tool. When I was initially developing the library, I was trying to figure out how to match dithered RGB values (containing quantization error or ...
makeworld's user avatar
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Float point placement with anti aliasing

I have an image of size H,W, and I would like to draw a point on this image at x,...
Mercury's user avatar
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0 answers
93 views

What is the best way to display complex number "images"?

I may be getting some details wrong (e.g. colour space vs. colour model), so please bear with me: I want to represent "images" consisting of complex numbers i.e. for each "pixel" ...
Chillpadde's user avatar
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Automate Image resize, scale, position for best quality (size)

I have a process where a web user selects a photo for a profile image. User is then presented with a canvas to zoom, rotate and move their image within a square viewport. Once satisfied, the user ...
johnw182's user avatar
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Turning colorized comic-art into uncolorized monochrome (line-art-inks-only B&W), not just very-light-grayscale

I'm trying to figure out how to go about removing the "colorization" of comic/cartoon/manga/etc drawn-art inputs where the black-ink strokes ("the line-art") are to be retained ...
Phil S.'s user avatar
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Image gradient of $x$-axis

I am trying to find gradient of the following image. Now shouldn't the gradient for $x$ be the vertical lines with respect to axes we have on the top left corner please?
Avv's user avatar
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2 votes
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AO Denoise Filter

I'm trying to implement a filter to denoise ambient occlusion data. What kind of filter do you suggest for the purpose? The techniques I've come across are the following: Gaussian filter (doesn't ...
leone ruggiero's user avatar
1 vote
1 answer
144 views

Edge-aware spatial denoising (Ambient Occlusion)

Reading through the source code of the XeGTAO project I found this function while looking for the denoise filter: ...
leone ruggiero's user avatar
1 vote
1 answer
103 views

3D to view plane projection

I am trying to draw points of a 3D sphere onto my monitor as if I was looking out into space. Me, the viewer, is at (0, 0, 0). The plane of my monitor is at (x, y, 1) and I have a sphere out in ...
Dan Wood's user avatar
0 votes
1 answer
85 views

How to identify images with similar content?

There's a set of pictures that if you take them literally, they're different. That is, there can be two images of the same thing among them, only in different hue. In addition, among these two, there ...
user309485's user avatar
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1 answer
126 views

Is it possible to convert Polar to Cartesian coordinates and map result to an image using opengl?

Is it possible to convert Polar to Cartesian coordinates and map result to an image? I want to get the output same as the distort depolar 0 from image magick. https:...
code0x00's user avatar
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1 vote
3 answers
528 views

loading images not through sampler

I am loading an image to shaders in Vulkan, but do not wish to use it as a texture. I wish to access the texels exactly as they are to decode the information I compressed in it. How should I do it? ...
Lily's user avatar
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1 vote
0 answers
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Algorithm for transforming PNG anti-aliasing to smooth paths

I read the pixels of PNG files via libpng and creates an array of alpha channels (showing visible pixels for a monochromatic image). int pixels[height][width]; <...
Googlebot's user avatar
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How to get a polyline from an image with consistent winding number

I am trying to find an algorithm for the following problem. Assume we have a black and white image. The image contains a white region that encloses a space. This space may be concave but it has no ...
Makogan's user avatar
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1 vote
1 answer
534 views

Is it possible to get recording device from meta data?

Im not sure if this is the right section to ask this question but i figured its worth a shot. Is it possible to take metadata from a video and use that data to identify what phone model was used to ...
xanttt's user avatar
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1 answer
60 views

35 mm equivalent focal length but with a different aspect ratio

I am doing some image processing and am a little bit confused about reporting a 35 mm equivalent focal length. I am working with a 640x360 image which has an aspect ratio of 1.7777. A 35 mm film is 36 ...
Evan's user avatar
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3 votes
1 answer
962 views

Compute Shader shared average value

Short Question: How can i integrate a buffer variable in a compute shader over each pixel i.e. how can i ensure memory coherence in such a case? Long Question: I've written a deferred renderer with ...
Sprinklerkopf's user avatar
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41 views

Efficient method of mapping any RGB tuple onto a list of RGB indices, is using some kind of partition plane viable?

Suppose we want to convert an RGB image into a paletted image. As an example, we may have a 1024x1024 image, and we want to map it onto 512 unique colors. All the colors are RGB. This is a problem of ...
Water's user avatar
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1 answer
1k views

Difference between Gray-Level and Gray-Scale?

What's the difference between the terms Gray-Level & Gray-Scale ? I think that Gray-Level refers to the matrix of light-intensities of the Black-White digital image itself whilst Gray-Scale refers ...
hazelnut_116's user avatar
3 votes
1 answer
61 views

What's the word for "how noticeable a particular part or pixel of an image is to a human"?

I remember hearing about an algorithm to calculate some property of each pixel of an image which represents how noticeable that pixel is to a human, and so how likely they are to notice if that pixel ...
Jacob Garby's user avatar
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1 answer
554 views

Can I write histogram equalization, blurring, sharpening grayscale image etc.. as shader programs with openGL?

...
Meganathan's user avatar
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1 answer
29 views

Filling pixels under or above some function

Seems like a simple problem, but I just cant wrap my head around it. I have a config file in which I declare a few functions. It looks like this: ...
Riki's user avatar
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0 answers
47 views

Building a higher-res detailed image from a video

I'd like to know if the following technology already exists, and if not, how feasible it would be to create something like this: I came up with an idea for creating a higher-res image that is put ...
Denis Savgir's user avatar
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0 answers
42 views

Pinhole Projection & Spheres [duplicate]

Would someone be able to explain why a sphere when projected with the pinhole projection model has its projected 2D image be an ellipsis. IN particular when the sphere is not directly in front of the ...
gmjasonx's user avatar
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0 answers
90 views

How to extrapolate an object from a photo taken with an iPhone

First off, this may not be the right group, however, it is the closest one I can think of. I took a few pictures of a computer panel at a known distance, but the angle to a corner would require the ...
John Schultz's user avatar
0 votes
1 answer
144 views

How is the multiplication in Gaussian Blur implemented

I have a question regarding how the Gaussian blur works. A pixel consists on the combination of 3 colors: R,G and B. I have read that the Gaussian kernel is multiplied by the input image by placing ...
George's user avatar
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0 votes
1 answer
254 views

Calculate the position and rotation of a quad in 3d space given a 2d projection of that quad from a camera

I am trying to build a VR tracking system with a laptop webcam, and I have succeeded in identifying, and tracking paper markers I put in front of my webcam. For context I am using OpenCV with the ...
Djgaven588's user avatar
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0 answers
42 views

How to render a rotated raster image with lesser aliasing

I am wondering about techniques for rendering a rotated and or scaled raster image. Currently I use the following algorithm Render everything at double resolution and store the result in ...
user877329's user avatar
1 vote
1 answer
91 views

How to pass only the needed portion of the data calculated in a fragment shader to another fragment shader?

I have an image and I want to draw an arbitrary number of objects on that image. The center coordinates of those objects are calculated inside a fragment shader after series of image processing ...
M. Samil Atesoglu's user avatar
1 vote
2 answers
66 views

splitting hue & saturating and leaving value behind

In an HSV model, the Hue is the color model. So when we split the image or remove H, should we get an image without rgb colors? Similarly, saturation is the gray shade. I read that images become more ...
Jbd's user avatar
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1 vote
1 answer
829 views

How to calculate spatial frequency of an image just in one direction?

FFT spectra is not what is needed; what I need is a histogram showing which frequencies are there in image in horizontal direction, and which one is dominant Such spatial frequency is usually known ...
ivan866's user avatar
  • 111
2 votes
3 answers
456 views

How to paint onto 3d models

I have searched this topic for very long time and have found basically no information on it. If we have a 3d model with a uv layout. What is the basic technique for 3d painting on said model with a ...
Lenny White's user avatar
0 votes
3 answers
129 views

How to remove background text from an image file

I have this image below, I want to get rid of the text 'MSAR IDs' that is in the background. I am extracting the numbers from the image with OCR, the numbers that have a white background get extracted ...
Abdul Malik's user avatar
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0 answers
28 views

Do scanners and scanning software compensate and enhance blurry sources?

I received a pdf from a client containing several invoices. Upon further inspecting, some lines on the invoice seem digitally produced. When I tried selecting the page, copying it then pasting it on ...
obi's user avatar
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0 answers
52 views

Are there algorithms besides Canny edge detection that can create consistent width edges?

Sobel edge detection is pretty much the quintessential way to get edges out of an image. It however suffers from certain quirks. One example is, because it's gradient, based certain surfaces exhibit ...
Makogan's user avatar
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3 votes
1 answer
78 views

Interpreting Image Processing Math Equation

I am reading "Image Processing and Analysis" by Chan and Shen, c 2005 SIAM. They introduce some notation I'm not 100% sure how to interpret: $$ u_0(x)=u(x)+n(x), x=(x_1,x_2) \in \Omega $$ They ...
Ron Jensen's user avatar
1 vote
0 answers
53 views

What modern C++ Unit Testing Framework do you use for highly parallel image, 3D and higher dimensional matrix processing workloads? [closed]

Most of the existing open-source libraries such as OpenCV, Tensorflow, and Pytorch use Google Test. I would like to know about strong alternative testing frameworks that thrive under a similar ...
mohankumarSriram's user avatar
1 vote
0 answers
77 views

HSI color space and RGB color space relationship in Steganography

I need to embed text in an image, research papers say HSI produces better mse and psnr therefore are better for steganography. I have RGB values(69,223,90) and its corresponding HSI is (127.223,0.458 ,...
Nikita's user avatar
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0 answers
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What fast algorithms can generate not-realistic but quite handsome animated landscapes?

I was looking for algorithms that quickly compute quite nice realistic, or not realistic, animated landscapes, in video format ("animated" = the camera moves, or the water is animated, etc.) But all I ...
JarsOfJam-Scheduler's user avatar