Computer Graphics Stack Exchange
Computer Graphics Stack Exchange

Questions tagged [image-processing]

181 questions
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2 answers

Rotate image around its center

I'm struggling with a problem with image rotation. I'm using the idea of "Rotation by area mapping" in the following link: http://www.leptonica.com/rotation.html My c# codes are as follows. The idea is first to find the dimension of the rotated…
user2719
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1 answer

Average intensity of an gray image

Suppose i have a 400*300 gray scale image.Now I want to scan each line horizontally and make the average of that line 128,such that the values get scaled as per their difference from mean(128) which will not cause any distortion to image.
Abdul Kahrim
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5
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1 answer

Instagram's fade effect

What is the pixel-level explanation of the fade effect, that was first popularized by Instagram? I want to implement this effect programmatically—that is, I want to understand what this effect is doing to each pixel. Also, if anyone could point me…
cauliflower
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4
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2 answers

reducing image size increases file size?

When I download this image: (source: ucn.edu.ni) then its total size is 341,0 kB. The image has a width of 2880 pixels and height of 1100 pixel and 1 X/Y resolution pixel/in. I opened the image with gimp and pressed scale image and reduced the…
Adam
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4
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2 answers

How enlarge parts of a video like snapchat lens filter

I writing the this video process app which requires the each video frame to be processed such that parts of the video are enlarged. As a reference, one of the snapchat lens filter enlarges the eyes of a person in the video. This is the exact effect…
crab oz
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4
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2 answers

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 several image decoding libraries in Rust for example…
jhk999
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3
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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 controllers, from low to high spatial frequencies, which…
Robert Angels
3
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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 would like to recreate its font; as the first step…
Leo B.
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3
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How to perform an image normalization after for example adding a constant to it?

I had some magical tasks to do on my lessons. I had to write an app which performs some operations: basic (adding, subtracting, multiplying a constant and a second image), geometric, filtering, histograms etc. There were ~50 tasks. I've made them…
Jacob
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3
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1 answer

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 was modified. I seem to remember the word sounded…
Jacob Garby
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2
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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 would not look too much distorted. Is there any…
Petr Hykš
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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 then perform a sharpen operation on it. For this…
Varun Vijaykumar
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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 uses triplanar texture mapping to put tilable "line…
Alan Wolfe
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What kind of image processing was used in the Facebook "Celebrate Pride" filter?

I am trying to recreate a filter that Facebook released back in 2015 when gay marriage was legalized in the US. Unfortunately, that filter no longer works/exists so people are left with only knockoff ones that dont do quite as good as a job. None of…
J.Doe
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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 neat way to do it. So here I provide 2 sample…
w.k
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