Questions on the image processing capabilities implemented in Mathematica.

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16
votes
4answers
862 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
310 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
316 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
535 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
150 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 ...
138
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) ...
20
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
148 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
273 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
132 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 ...
32
votes
1answer
967 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 ...
14
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
127 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
734 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
454 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
110 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
281 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
158 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
430 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
329 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
528 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: ...
23
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 ...
23
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
208 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 ...
9
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
123 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
249 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
241 views

Applying a transformation rule on an Image

I haven't been able to figure out why the following doesn't work: ...
9
votes
1answer
792 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
673 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
286 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
542 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
126 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
262 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
200 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
438 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
2k 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: ...
3
votes
1answer
209 views

Weird resampling when I try to export an Image

Mathematica language newbie here. I wrote the following code to quantize an image: ...
26
votes
5answers
967 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.
11
votes
1answer
298 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 ...
2
votes
1answer
440 views

Extract data from plots in papers including error bars

I would like to know how to extract data from plots in a paper and, also, how to do that in a way that include error bars. I know there are specific softwares to do that, e.g. Plot Digitizer, which ...
0
votes
2answers
202 views

Number of edges to each polygon of a graph constructed from an image

I have an image which looks like from How to convert an image to a graph and get the positions of the edges? which by using MorphologicalGraph becomes a graph ...
34
votes
3answers
3k views

Image processing: Floor plan - detecting rooms' borders (area) and room names' texts

Here is a simple building floor plan. I would like to derive the rooms as (rectangular) components and the names of the rooms. This is very common representation of building floor plans. The ...
2
votes
1answer
161 views

How does DistanceFunction work with images in ClusteringComponents?

Does anyone know the syntax to DistanceFunction? I am trying to define my own function to use with ClusteringComponents; e.g., ...
3
votes
1answer
268 views

Filter bright dots from the gradient of the image

I am wondering how to filter out bright dots in the picture, which are caused by background noise. I have used gradient filter in mathematica but it doesn't help. Is there anyway, that I can plot ...
3
votes
2answers
194 views

How to remove border points from InputForm?

I have this code, and it generates the below ListStreamPlot. The second graph is the ListStreamPlot overlaid with the points ...
4
votes
1answer
336 views

How can I find a particular character in an image that has many similar Chinese characters? [duplicate]

The Chinese characters "竟" and "竞" are very similar in their appearance. I am trying to find "竟" in the following picture. I tried use TextRecognize but it ...