Questions tagged [image-processing]
The image-processing tag has no usage guidance.
180
questions
-1
votes
0
answers
43
views
How can I change the dpi of an image?
I tried this site to change the dpi of an image, but it didn't really change anything, based on the size of the image and the image properties displayed when I opened the "converted" image ...
1
vote
1
answer
88
views
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, ...
- 111
5
votes
1
answer
93
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 ...
- 367
1
vote
0
answers
53
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 ...
- 11
2
votes
1
answer
71
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)?
...
- 21
0
votes
0
answers
29
views
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
- 101
0
votes
0
answers
18
views
How does denoising factor into most render engines + practical question
I'm a student working on an experimental animation.
The animation has been selected to be screened at a festival, but they would like a resolution that is beyond what my single graphics card can ...
- 1
1
vote
0
answers
40
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 ...
- 11
0
votes
0
answers
49
views
Opengl binding different mipmap levels of same texture2darray for use in compute shader. How to handle variable nr of levels?
So I want to make a compute shader that uses a coarse-to-fine approach.
As I have learned about open gl mipmap levels it seems they could be very useful.
However the only binding method which I have ...
- 125
4
votes
2
answers
88
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 ...
- 43
4
votes
1
answer
221
views
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 ...
- 143
2
votes
0
answers
46
views
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,...
- 121
1
vote
0
answers
78
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" ...
- 11
0
votes
0
answers
19
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
123
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
32
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
2
votes
0
answers
111
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 ...
- 367
1
vote
1
answer
122
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:
...
- 367
1
vote
1
answer
102
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 ...
- 21
0
votes
1
answer
80
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
1
answer
89
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
418
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
1
vote
0
answers
41
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
36
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 ...
- 1,696
1
vote
1
answer
333
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 ...
- 11
0
votes
1
answer
57
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
776
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 ...
- 163
0
votes
0
answers
37
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
727
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 ...
- 103
3
votes
1
answer
60
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 ...
- 133
0
votes
1
answer
509
views
0
votes
1
answer
27
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
46
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 ...
- 1
0
votes
0
answers
80
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 ...
- 101
0
votes
1
answer
126
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
217
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
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 ...
- 101
1
vote
1
answer
88
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
56
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
749
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
378
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 ...
- 516
0
votes
3
answers
127
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
50
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 ...
- 1,696
3
votes
1
answer
71
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 ...
- 133
1
vote
0
answers
52
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
73
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 ,...
- 11
0
votes
0
answers
55
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
71
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