Questions on the image processing capabilities implemented in Mathematica.
18
votes
4answers
335 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 ...
2
votes
1answer
259 views
non-linear trend reduction using thresholds
Doing some mappings of the earth magnetic field results in the left-hand figure below (which consists of 181 profiles):
To improve this I tried a non-linear trend reduction using, for example,
...
2
votes
1answer
153 views
Weird resampling when I try to export an Image
Mathematica language newbie here. I wrote the following code to quantize an image:
...
3
votes
1answer
68 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.
...
36
votes
3answers
11k views
How to create new “person curve”?
Wolfram|Alpha has a whole collection¹ of parametric curves that create images of famous people. To see them, enter WolframAlpha["person curve"] into a Mathematica ...
2
votes
2answers
161 views
How can I import images from a Microsoft SQLServer database?
I have a table with binary data (images) in Microsoft SQlServer. I want to import that data and convert it into Image format. I wrote the following code, but it's ...
2
votes
3answers
134 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
82 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 ...
25
votes
1answer
459 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 ...
17
votes
3answers
705 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 ...
13
votes
4answers
319 views
How to separate paths from the output of EdgeDetect?
I have been trying to find a way to separate the various closed paths that can be output by EdgeDetect. For example, taking the output of:
...
41
votes
5answers
5k views
How to create hedcut style images?
Yesterday the hedcut style was brought up in chat. How can we create a hedcut-like style automatically in Mathematica, using a photograph as a starting point?
I am looking to create a similar ...
15
votes
6answers
575 views
How do I make an image “nearly” black and white?
Using the following code, I downloaded an image from the web and adjusted the image to obtain the "negation" of the image:
...
12
votes
6answers
640 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, ...
3
votes
1answer
221 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
299 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 ...
0
votes
1answer
52 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 ...
2
votes
1answer
44 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 ...
5
votes
3answers
215 views
Inserting button in image
Can I insert a button in an image at specified location? I have tried but it shows Button is not a graphic function.
5
votes
4answers
137 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 ...
1
vote
2answers
81 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:
...
5
votes
1answer
260 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 ...
3
votes
0answers
103 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
1answer
126 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)?
0
votes
0answers
21 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 ...
5
votes
5answers
334 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 ...
9
votes
3answers
183 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:
...
20
votes
3answers
657 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 ...
5
votes
3answers
263 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)
...
0
votes
2answers
121 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 ...
25
votes
3answers
909 views
xkcdConvert routines perform slower in Mathematica 9
I am experiencing some rather large performance decreases in Mathematica version 9.0 using the xkcd-styled plotting routines.
I had used the xkcdConvert code ...
8
votes
3answers
450 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
87 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 ...
2
votes
4answers
126 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
1answer
252 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 ...
6
votes
2answers
152 views
Applying a transformation rule on an Image
I haven't been able to figure out why the following doesn't work:
...
9
votes
3answers
311 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 ...
12
votes
2answers
592 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:
...
0
votes
1answer
121 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 ...
2
votes
2answers
151 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 ...
5
votes
1answer
79 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. ...
6
votes
1answer
116 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 ...
1
vote
0answers
114 views
Exporting images leaves syntax artifacts [closed]
I'm exporting Images (using .Net MathLink) and finding syntax artifacts in:
Images:
RTF:
PDF:
I've tried a couple of things such as ...
7
votes
3answers
248 views
Radon function result's repeatability
I want to get a Hough transform of some edged image.
When I compare the same transformation on the same image I got different results.
...
135
votes
2answers
35k views
Help find a bright object on Mars!
In today's news, scientists found a bright object on one of Curiosity's photos (it's near the bottom of the picture below). It's a bit tricky to find - I actually spent quite some time staring at the ...
0
votes
0answers
73 views
How to get Contours/maxima for an image in a useful form [closed]
I have some images in which I would like to find the locations of various maxima, plus the contour lines at a level e.g., 50% of that maximum intensity.
As a first step, I did a FourierDCT on the ...
18
votes
5answers
594 views
Voronoi diagrams for generators other than points
Any suggestions how to determine Voronoi diagram for sites other than points, as e.g. in the picture below? Input is a raster image.
9
votes
1answer
159 views
Precise cropping with ImageCrop
The built-in ImageCrop function "effectively removes borders from image whose pixel value distribution is almost uniform" (emphasis mine). I need an efficient ...
1
vote
0answers
76 views
Why does animating images overlayed with graphics primitives take much longer than animating either individually?
So I start by making a list of images with
images = Image[ArrayPlot[Import[ (* filenames *) ]]]
Then I run some complicated code that extracts the coordinates ...
19
votes
1answer
914 views
Is there a way to convert an image into a Graph?
I'm trying to convert an image with several overlapping dots into a Graph. The goal is to be able to derive the Kirchhoff matrix for the randomly created "network ...
