Questions tagged [image-processing]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0 votes
0 answers
14 views

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 ...
  • 101
1 vote
0 answers
111 views

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 ...
  • 11
0 votes
0 answers
25 views

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?
  • 101
1 vote
0 answers
37 views

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 ...
1 vote
1 answer
50 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: ...
1 vote
1 answer
95 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 ...
0 votes
1 answer
58 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 ...
0 votes
0 answers
22 views

How to determine polygon vertices?

I have an image in two colors - black and white, no halftones or other colors. It is known, that the only thing this image contains is a single solid filled polygon of the black color, and the rest of ...
  • 101
0 votes
1 answer
47 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:...
  • 101
1 vote
3 answers
174 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? ...
  • 31
0 votes
0 answers
24 views

How Imagemagick's +distort DePolar works?

I can't use imagemagick in my scenario so trying to figure out the logic about the imagemagick's distort depolar. magick image.png -distort DePolar 0 image.png ...
  • 101
1 vote
0 answers
37 views

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]; <...
  • 131
1 vote
0 answers
30 views

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 ...
  • 1,449
0 votes
0 answers
79 views

How to convert a fisheye image to equirectangular image?

Hi i am rather new to computergraphics but i am trying to map fisheye image to an equirectangular image. The method i am following to do this is getting a lat/lng from equirectangular image and use ...
  • 101
0 votes
1 answer
35 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 ...
  • 1
0 votes
1 answer
47 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 ...
  • 3
3 votes
1 answer
288 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 ...
0 votes
0 answers
31 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 ...
  • 101
0 votes
1 answer
92 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 ...
0 votes
0 answers
105 views

How to generate a thumbnails index file?

Given a folder full of pictures, how can I generate a thumbnail index file for them? Basically I want to generate a single picture that has thumbnails of everything inside the folder, with a file name ...
  • 1
3 votes
1 answer
55 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 ...
0 votes
1 answer
312 views

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

...
0 votes
1 answer
26 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: ...
  • 111
0 votes
0 answers
45 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 ...
0 votes
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 ...
0 votes
0 answers
39 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 ...
0 votes
1 answer
75 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 ...
  • 1
0 votes
1 answer
128 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 ...
0 votes
0 answers
38 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 ...
1 vote
1 answer
75 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 ...
1 vote
2 answers
41 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 ...
  • 113
1 vote
1 answer
388 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 ...
  • 111
2 votes
3 answers
129 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 ...
0 votes
3 answers
120 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 ...
0 votes
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 ...
  • 1
0 votes
0 answers
46 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 ...
  • 1,449
2 votes
1 answer
51 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 ...
1 vote
0 answers
48 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 ...
1 vote
0 answers
49 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 ,...
0 votes
0 answers
53 views

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 ...
1 vote
1 answer
69 views

Given a background image B and a composie image of A OVER B, can we somehow recover image A?

I often find myself in the situation where I have some old image where I composed a translucent overlay on top of a background, but then lost (or more likely discarded) the overlay. I still have pre-...
  • 113
0 votes
0 answers
148 views

Visualize the variance of an image

Let $h_j$ denote the image reconstruction filter of pixel $j$. I'm estimating the color value $$I_j=\int h_jf\:{\rm d}\mu$$ of the $j$th pixel (see [Veach, Section 8.2]) by an asymptotically ...
  • 163
2 votes
1 answer
94 views

Controlling "zoom" and "position" of a cubemap in shaders

I am trying to mimic reflections in image composition using shaders. I have gotten this far: In this image the floor is "reflecting" the back wall, however the reflection is uncanny because the ...
  • 1,449
3 votes
0 answers
142 views

Upscaling screenshots with subpixel rendered text

Upscaling a screenshot with subpixel antialiased text produces unpleasant color fringes, e.g. why does black text have orange and blue pixels This is especially annoying when trying to show an ...
1 vote
0 answers
36 views

Extract object from image and apply it to different image

SHORT BACKGROUND: I am developing a neural network based model to differentiate benign and malignant ovarian tumors. I am working with transvaginal ultrasound images, some of which contains yellow ...
  • 111
0 votes
0 answers
47 views

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?
1 vote
1 answer
328 views

Extracting information from EXR Files

I am relatively new to computer vision and image processing. I have a single EXR file with 7 channels: 1-3 give me the RGB values, 4-6 give me the surface normals coded as RGB values and 7th channel ...
1 vote
1 answer
759 views

How do you add text dynamically to an image and export it?

Apologize for crossposting, but I posted this in Stack Overflow and thought it might be a better post here. Recently, Spotify released their 2019 Spotify wrapped web application, which is essentially ...
  • 111
1 vote
1 answer
72 views

What kind of denoising must follow locally adaptive binarization?

I am experimenting with local (adaptive) grey threshold for the binarization of B&W photographs of yellowed manuscripts: I got adaptive thresholding working in both scikit-image and cv2. In both ...
0 votes
1 answer
763 views

How RGB images are formed when normalized between 0 and 1

There is a popular technique of normalising images by dividing each pixel with 255 so that it comes in the range of 0 and 1. But, then how the same colours are formed when we normalize images. for ...
  • 129