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Questions tagged [image-processing]

Anything related to digital image processing, i.e. the theory and the techniques used to extract or manipulate information from digital images.

Image Processing involves any kind of signal processing in which the input is an image. The output can also be an image, or it can be information relative to the input image. Most image processing techniques involve treating the image as a two-dimensional array and applying standard signal processing techniques to it. Though optical and analog image processing are both well defined in the space of image processing, the tag image-processing in SO solely refers to digital image processing.

A good start on the field is having a look at the next links:

For an in-depth collection of explanations of a number of image processing topics, have a look at CVonline.

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What is "semantic segmentation" compared to "segmentation" and "scene labeling"?

Is semantic segmentation just a Pleonasm or is there a difference between "semantic segmentation" and "segmentation"? Is there a difference to "scene labeling" or "scene parsing"? What is the difference between pixel-level and pixelwise…
Martin Thoma
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c# Image resizing to different size while preserving aspect ratio

I'm trying to resize an image while preserving the aspect ratio from the original image so the new image doesn't look squashed. eg: Convert a 150*100 image into a 150*150 image. The extra 50 pixels of the height need to be padded with a white…
sf.
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Automatic contrast and brightness adjustment of a color photo of a sheet of paper with OpenCV

When photographing a sheet of paper (e.g. with phone camera), I get the following result (left image) (jpg download here). The desired result (processed manually with an image editing software) is on the right: I would like to process the original…
Basj
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How can I measure the similarity between two images?

I would like to compare a screenshot of one application (could be a Web page) with a previously taken screenshot to determine whether the application is displaying itself correctly. I don't want an exact match comparison, because the aspect could be…
Antoine Aubry
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Python - Find dominant/most common color in an image

I'm looking for a way to find the most dominant color/tone in an image using python. Either the average shade or the most common out of RGB will do. I've looked at the Python Imaging library, and could not find anything relating to what I was…
Blue Peppers
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Image fingerprint to compare similarity of many images

I need to create fingerprints of many images (about 100.000 existing, 1000 new per day, RGB, JPEG, max size 800x800) to compare every image to every other image very fast. I can't use binary compare methods because also images which are nearly…
Philip Dreyer
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Combining Two Images with OpenCV

I'm trying to use OpenCV 2.1 to combine two images into one, with the two images placed adjacent to each other. In Python, I'm doing: import numpy as np, cv img1 = cv.LoadImage(fn1, 0) img2 = cv.LoadImage(fn2, 0) h1, w1 =…
Cerin
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Near-Duplicate Image Detection

What's a fast way to sort a given set of images by their similarity to each other. At the moment I have a system that does histogram analysis between two images, but this is a very expensive operation and seems too overkill. Optimally I am looking…
The Unknown
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GD vs ImageMagick vs Gmagick for jpg?

I am in the step to abandon GD for manipulating image in my website - it is awful. Everyone saying to use ImageMagick because they are better than GD, but what about ImageMagick vs Gmagick (Swiss Army knife of image processing)? Zend has a pretty…
dynamic
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Data Augmentation in PyTorch

I am a little bit confused about the data augmentation performed in PyTorch. Now, as far as I know, when we are performing data augmentation, we are KEEPING our original dataset, and then adding other versions of it (Flipping, Cropping...etc). But…
Fawaz
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What are keypoints in image processing?

When using OpenCV for example, algorithms like SIFT or SURF are often used to detect keypoints. My question is what actually are these keypoints? I understand that they are some kind of "points of interest" in an image. I also know that they are…
dephinera
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Merging two images

I need to merge two images (BufferedImage) in Java. It wouldn't be a problem if there was no transparency. The base image already has some transparency. I want to keep this as it is and apply a "mask" to it, the second image. This second image has…
GuilhermeA
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How does photoshop blend two images together?

Can somebody please explain how Photoshop blends two images together so that I may reproduce the same effects in my application.
Nathan Moinvaziri
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Is it possible to tell the quality level of a JPEG?

This is really a two part question, since I don't fully understand how these things work just yet: My situation: I'm writing a web app which lets the user upload an image. My app then resizes to something displayable (eg: 640x480-ish) and saves the…
nickf
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Resampling a numpy array representing an image

I am looking for how to resample a numpy array representing image data at a new size, preferably having a choice of the interpolation method (nearest, bilinear, etc.). I know there is scipy.misc.imresize which does exactly this by wrapping PIL's…
Gustav Larsson
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