Questions on the image processing capabilities implemented in Mathematica.

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1
vote
2answers
225 views

Understanding the coordinate system for ImageTake

I have a point in an image which I can locate by right clicking and using my mouse. Call this point $p = (100,100)$. I'd like to use ImageTake to grab an image, centered on this spot $p$ with $k = ...
6
votes
4answers
5k views

Fitting a two-dimensional Gaussian to a set of 2D pixels

Imagine I have a set of data like the following: ...
0
votes
1answer
128 views

Returning a bounding disk or box centered on a coordinate in a 2D image

Provided a coordinate $c_k$ in a two-dimensional image, how can I return all of the pixels in a bounding disk or rectangle centered on $c_k$ of some specified dimension $d$? Update: Hat tip to Kuba ...
18
votes
1answer
411 views

Color scheme used by Colorize?

The Colorize function is often used to display the results produced by MorphologicalComponents: ...
0
votes
1answer
140 views

Returning lists of pixels connected through their Moore neighborhoods

I have a binarized image in Mathematica 9, and I would like to generate a list of coordinates for clusters of pixels connected through their Moore neighborhoods, e.g. ...
4
votes
1answer
267 views

Volumetric Rendering of cylinder symmetric radial image

I would like to render a cylinder symmetric radial cross-section with Image3D. As an example one could use the propagation of a Bessel Beam through a Lens: Here the cylinder axis is the bottom of ...
10
votes
3answers
476 views

Image Processing: Concrete test blocks

Background Concrete is mixture of aggregates and cement. Aggregates are composed of different sizes and colors. Core samples are taken by drilling in order to test the strength of concrete . They are ...
13
votes
2answers
396 views

Improve TextRecognize[] on numbers

I have an image contain only numbers, and TextRecognize fail to recognize some numbers: img=; TextRecognize[img] (*826718*) The documentation says that "The ...
0
votes
3answers
442 views

Derive a smooth circle with cusp from an image

question 1 get the center (sample data) sample is the black circle with cusp. ...
23
votes
2answers
1k views

Find radii of concentric circles in image

I have an image of concentric circles, I would like to find the radii of the circles (only the innermost few are important). I've had a go using what I could find in previous posts, but am a bit ...
16
votes
4answers
986 views

Digital filter of image in Fourier space

Consider the contour plot below, of a function f(x,y) - which is calculated numerically by solving some equations. If one looks carefully, one can observe two types of waves, to the left and right of ...
1
vote
2answers
343 views

Image Restoration

I want to degrade the image, and then execute the restoration, such as a lena.jpg. I tried this: ...
5
votes
3answers
356 views

Getting RGBA data from an image

What is going on with returned data in the following examples? It appears ImageData returns different types depending on the what data is passed into ...
15
votes
2answers
595 views

Twirl Image Transformation

I am looking to reproduce the functionality of Photoshop's "Twirl" filter, which twists an image that originally looks like this (pulled from this page): Into this: Ideally, I'd like it to ...
4
votes
3answers
159 views

Maintaining map dimensions after using Colorize

I am trying to beautify a map by using Colorize as demonstrated in the Mathematica documentation. First, I import a shapefile from DIVA-GIS for France which ...
10
votes
4answers
1k views

How do I find the coordinates of points in this image?

I have never used image processing with Mathematica. I need to get the coordinates of the red points from this image I made in Illustrator. Is there a way to get Mathematica to read or detect the ...
140
votes
2answers
56k views

QR Code in shopping cart handle

This week, the market people from my work wanted to put QR codes in shopping cart handles, but when they tested it, the QR code did not work. I noted that the cylindrical curvature (even small) ...
21
votes
4answers
2k views

How can I detect an ellipse in a photo?

I tried to detect the rim of the following cup as an ellipse. I've tried the solutions given in How to find circular objects in an image? to detect the ellipse, but the detection result was not ...
3
votes
1answer
155 views

Resampling when using image as Texture

How to get sharp pixel boundaries with Texture? I'd like to have only black/white in the example below, no gray. ...
2
votes
3answers
298 views

Using ImageTransformation[] with a lookup table

I need to transform images by ImageTransformation in a time critical application. Therefore I precalculate a lookup table lut of ...
0
votes
1answer
165 views

TextRecognize with crosses, circles and spaces results into oddities, why?

I am investigating this answer here about detecting crosses and circles with TextRecognize. I tried to solve this problem here by directly using the builtin command TextRecognize but it does not work ...
33
votes
1answer
1k views

Finding areas of beings in microscopic image

I've got lots of images of diatoms. I need to get a list of their equivalent radii. It's not crucial to get them all, as long as those missed don't mess with the radius distribution (as would ...
15
votes
6answers
1k views

How to find major color in a picture?

I want to find the major color (the color which appears most often) in a picture and do some analysis later. For example, if I have this picture: What I want to do is find out that gray, red, ...
0
votes
1answer
138 views

Outputting a set of graphics 3D objects with positions defined by one array and colors by another? [duplicate]

I have a set of 2- or 3-space coordinates in an array, $(v_1,...,v_N)$, and an array of RGB color values (outputs from ImageValue[]) for each coordinate, $(c_1,...,c_N)$. How can I output a ...
3
votes
1answer
822 views

Detection of horizontal lines in an image

Ok I'm trying to detect horizontal lines in an image. But the problem is that the line is quite obscure. So I'm not sure if it is even possible to extract that. I tried many different filters, but ...
5
votes
4answers
478 views

How can I return the color at a coordinate in an image?

I have an imported and cropped image: TestPicture = Import["filepath.jpg"]; TestPictureCropped = ImageCrop[TestPicture, Min[ImageDimensions[TestPicture]]]; How ...
3
votes
1answer
115 views

How do I access the binary matrix underlying an EdgeDetect output?

Applying EdgeDetect to an image generates a black and white edge-detected image, which I suspect corresponds to an underlying binary matrix. How can I access this ...
6
votes
4answers
300 views

How do I overlay corresponding values over each frame of an animation?

I recorded a phenomenon using video capturing (phen.avi, imported into Mathematica) and simultaneous measurement of some electrical properties of that phenomenon (a ...
2
votes
2answers
175 views

Image processing - How can I apply an operation to several images at once?

I imported pictures into Mathematica, and used names for them that follow the easy scheme "name" string joined with an integer, ranging from 14 to 20. Printing these images on screen works nicely: ...
4
votes
0answers
490 views

looking for a generalised Hough Transform function or a least a function to locate circles

I am looking for a generalised Hough Transform function or a least a function to locate circles (position of center and radius) in a image. There is the standard Hough line search function ...
0
votes
0answers
40 views

How to use an arbitrary closed region to extract an image region of interest [duplicate]

I am working on images and I need to be able to extract into a list all the image points that fall within a closed region, such as gotten from using "get coordinates". I can extract the points from ...
0
votes
1answer
362 views

How can I find lines of a certain angle(s)?

ImageLines implements the Hough transform, but how do I search for only lines within some threshold of a certain angle(s)?
4
votes
5answers
1k views

Get Coordinates in Image Processing

I'm new to Mathematica. I'm very impressed about it's abilities. It's very easy to achieve complex tasks. But I fail the simple ones. How can I get coordinates in image processing? I'd like to ...
12
votes
3answers
598 views

Rotate a grid, made up of lines, so that it aligns with the xy axes

While working on an answer for another problem I hit upon one of my own. I took the image given in that question and cleaned it up so that I could detect the grid lines: ...
24
votes
3answers
1k views

How to detect crosses and circles in 60x60 raster images?

I have hand-written 60 pixel times 60 pixel squares. I need to detect whether they are empty, x or circle. TextRecognize function fails. Is there some other function to process this kind of raster ...
24
votes
3answers
1k views

How to find the center of a circular pattern?

I am writing an algorithm that finds the center of 500 x 500 pixels images coming from a live feed from a camera at 50 Hz. So it has to be quick! The images are images of an optical field which looks ...
0
votes
2answers
219 views

Find white regions in image

At the white regions of this image I want to add a few random arrows. I would like to realize two different of adding the random arrows: The arrows may not leave the white region The arrows have to ...
10
votes
3answers
2k views

Composing an image with a plot

I'm trying to illustrate the solutions to a textbook problem dealing with quadratic functions. This will involve plotting a quadratic and overlaying the plot and the image. Here is the textbook ...
2
votes
1answer
129 views

Round image corners [duplicate]

I just read StackExchange blog It’s OK to Ask and Answer Your Own Questions which even encourages it and decided to ask about a problem I now know how to solve. But I found an elegant answer only ...
3
votes
4answers
254 views

Find components which have intersections with designated lines

I have an image with several disconnected components, and I want to find all the components which have intersections with some designated lines which I generated previously. The image: And the line ...
8
votes
3answers
248 views

Applying a transformation rule on an Image

I haven't been able to figure out why the following doesn't work: ...
10
votes
1answer
921 views

Search the neighborhood area along a line in an image

I am trying to search for the black areas along a line (the horizontal line shown below). Though it is straight in this picture, it could be of irregular shape in other cases. It seems that the ...
10
votes
3answers
763 views

Extract connected components from PNG image file and write to individual PNG files

Given the PNG image below with the three leaves in it, I'd like to extract each individual leaf and write it to its own PNG file, using Mathematica 9. Note that in the original image, the box bounding ...
0
votes
1answer
297 views

Automatically shrink stretched images back to their original dimensions

We all sometimes find images on the web that are carelessly stretched to larger dimensions than original, which results in nothing but a reduction of the detail / dimensions ratio. See Original vs ...
5
votes
3answers
653 views

Parameters for the CIE XYZ Color Space in Mathematica

In Mathematica, producing a color based on its RGB parameters is easy; one can use (for example) ...
5
votes
1answer
130 views

Scaling an image with “Drawing Tools” primitives on it

Imagine I doodle with the "Drawing tools" pen, or place lines on an image after importing it. Now say I want to scale this image by some constant factor $C$ while maintaining the same aspect ratio. ...
2
votes
2answers
284 views

Introduction of bias during brightness and contrast manipulation of an image

Quoting from Nature magazine's "Image integrity" guidelines: Processing (such as changing brightness and contrast) is appropriate only when it is applied equally across the entire image and is ...
6
votes
1answer
218 views

Digital Elevation Maps (DEM) are Warped yet ReliefPlot renders as a rectangle - how do i join?

I downloaded several USGS Digital Elevation Maps (DEM files) corresponding to 12 adjacent areas. Each file Imports[] into Mathematica and I can render the individual ...
5
votes
1answer
474 views

How do I put an image on the complex plane?

I watched this video and became interested in transforming an image. But I have no good idea on how to embed an image in the complex plane using Mathematica. I have a method that seems to work, but ...
15
votes
2answers
3k views

How can I detect a rectangular region of interest in a picture?

Here is a downsampled input image I converted to greyscale. To select the rectangular region of interest we first preform preprocessing: ...