Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [image-processing]

This tag is for the mathematics involved in the field of image processing. Many such questions are also appropriate for Signal Processing Stack Exchange.

This tag is for mathematical questions about the field of image processing. Note: programming issues related to image processing belong on other Stack Exchange sites: Stack Overflow, Signal Processing or Computer Science.

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Whats is a template image in segmentation problem

I'm actually reading a paper about brain segmentation but i don't understand whats is an 'Template image', here a part if the paper: "We denote T a template image and S its segmentation (obtained manually or semi-manually). We also suppose that T is…
Zouitine Mehdi
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intensity transformation 16-bit image to a 8-bit image

Give an intensity transformation function T for converting a 16-bit image to a 8-bit image, i.e. T takes an integer from {0,1,2,...,65535} and returns an integer from {0,1,2,...,255}. Can we use $s = T(r) = \left \lfloor \sqrt{r}\right \rfloor$?
meta_warrior
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Explaining template matching algorithm's formula (opencv2)

I am struggling to understand OpenCv's formula for the CV_TM_CCOEFF template matching algorithm Where Specifically, in R(x,y), what do the x' and y''s mean? I dont imagine they are derivatives, because the values are all integers so its derivative…
peterxz
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How to interpolate between these two points in time?

I have an image which is positioned at (x=0, y=177, scaleW=1.0, scaleH=1.0) at say $t_0$, and I need it to be positioned at (x=35, y=110, scaleW=0.65, scaleH=0.65) at $t_1$. How do I find keyframes in between, what kind of interpolation should I…
Azlam
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Images Aspect Ratio

How to change the aspect ratio of an image while maintaining its area? I would like to know the math behind it because I can't make any sense of it. Example: image with $h = 128$, $w = 128$, area $= 16384$, ratio $= 1:1$. When ratio is $1:2$, it…
Ibrahim Sherif
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Why averaging filter work?

To smooth an image we use often use a 3 by 3 matrix of ones divided by the average or mean filter Intuitively I understand that we take the average gray levels value so there will be no "high" or "low" values, but mathematically how can one show it?…
gbox
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How do we find first order estimate of the given entropy of the following image

What is the solution for this answer? Should we use log base 2 in the formula?
Madhurya Krishnan
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Energy of a color image

I am trying to calculate the energy of an RGB image by summing up the squares of pixel values (i.e., $\sum_{i=1}^{W}\sum_{j=1}^{H}(R^2+B^2+G^2)$). I was wondering if this is the right way to calculate the energy of a color image. I found literature…
user3817020
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How to "re-calculate" a image from a specified set of colors?

What i have is 2 images, the goal is to redraw the second image but only use the colors from the first image. I have a solution for this already but currently its too slow (you can test it here http://167.99.243.66/). Essentialy it takes all the…
Vajura
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Relation between image point , 3D counterpart and the general plane

So I'm a bit stuck on a problem that wants me to show the relation between any image point and it's corresponding 3D point can be represented by a 3x3 matrix. My idea was to use the general form of the camera model which has the 3D point transposed…
Marorin Q
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Mapping image's 4 corners to warped 4 corners...

I need to write a script for an illustration program which will take an image, allow the user to outline the rectangular face within the image, and then warp the image so that the rectangular face is actually rectangular to the viewing plane. See…
Jed
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Analysis Method to Deblurring Image

To deblur the image. usually we consider the model $$B=A(X)+e,$$ where $X$ is the expected image, $A$ is the convolution/matrix action and $B$ is the blurred image. I know there are some matrix-methods to deal with the above case, e.g. in the book…
DLIN
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Calculate how much I have to reduce a picture to reach a given size

I have an application where I need to resize the users picture to max. 50KB To resize I use a Method that sizes the picture to a given Width/Height. The picture is a Bitmap with max. 8BPP. (Width * Height * 8) = Size in Bits What I need to know now…
Lexu
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Solving this image focal problem?

Suppose you wish to form an image of a 1cm wide object, 50cm away, on a sensor measuring 20mm. How can I calculate the magnification factor required and the focal length of the lens? I'm not sure how to begin.
user1085773
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Need help coming up with (or finding) an image metric for $N\times M$ image.

So say you have the set of all unsigned $8$ bit grayscale, $N\times M$ images. This means there are $256^{NM}$ images in this space. If these images were binary, you could represent them with an $NM$ bit binary digit, but since your intensity values…
GregoryNeal
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