# Steve Eddins

### MathWorks

MATLAB user since 1987. MathWorker since 1993. Amateur French horn player. MATLAB design and development, image processing algorithms.

Image processing blog: https://blogs.mathworks.com/steve/

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**Content Feed**

Matlab working very slow on my m1 MacBook Pro

See this answer and follow it for updates related to this problem.

22 dagar ago | 2

Shouldn't bwconvhull() be idempotent?

Hi Matt, At a general level - and speaking from too much personal experience - expectations about geometrical operations such a...

30 dagar ago | 2

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Issue in plotting binary image boundaries with real axis values

The function bwboundaries returns boundary values in pixel coordinates. You'll need to scale those to world coordinates yourself...

ungefär en månad ago | 0

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How to change boundary width in Active Contour Method?

Call visboundaries with an output argument. That output argument will be an hggroup object containing two lines. You can then ma...

ungefär en månad ago | 0

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Published

Use imbinarize to Threshold Gray-Scale Images

Today, I want to convince you to use imbinarize instead of im2bw.Background: I recently saw some data suggesting that many...

ungefär en månad ago

Published

NaN Sightings

Some of us at MathWorks like to share our "NaN sightings." Here is an example to show what I mean. This is a screenshot of...

2 månader ago

Published

How to Use a Custom Interpolation Kernel with imresize

Recently, I was talking with MathWorks writer Jessica Bernier about the reference page for the imresize function. Jessica...

3 månader ago

Published

How to Run Blog Post Code in Your Browser

I have published more than 560 blog posts here since 2006, and I estimate that about 98% of them started out as MATLAB...

3 månader ago

Published

Plotting a* and b* colors

Today's blog post comes from planning one topic, but then taking a sharp left turn and doing something else completely. I...

3 månader ago

Having graycomatrix rescaling problem

Here is the doc for the NumLevels parameter: Number of gray levels, specified as an integer. For example, if NumLevels is 8, gr...

4 månader ago | 0

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How to find the center position under the saturation spot signal

Try converting the image to binary using imbinarize and then using regionprops to compute the centroid. rgb = imread('image.bmp...

4 månader ago | 0

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How to bold x axis labels

Try setting the TickLabelsInterpreter property to 'tex', like this: plot(1:10) ax = gca; ax.XAxis.TickLabelInterpreter = 'tex...

4 månader ago | 0

three difference vectors and plots

I have copy-pasted your code below, exactly as entered in your question. It runs and produces the plot with no error. I suggest ...

4 månader ago | 2

Problem with datetime and daily values

Use a timetable and the retime function. >> T = readtable("data.xlsx"); >> head(T) ans = 8×5 table Date ...

5 månader ago | 0

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What is the best way to count the occurrences of two table columns together?

In my previous answer, I forgot that grpstats is in the Statistics and Machine Learning Toolbox. Here is an answer using groupsu...

5 månader ago | 1

What is the best way to count the occurrences of two table columns together?

I think grpstats will do what you want: >> grpstats(T,["A" "B"]) ans = 4×3 table A B Grou...

5 månader ago | 0

Find peaks not working on my data set

I suspect the issue is with the x-coordinates that you are using to plot the peaks. You are plotting the peaks against the indic...

5 månader ago | 1

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Assign values in a matrix

One idea is to use a timetable and the retime function. Suppose I have the following matrix for a 4-minute charge and a 3-minute...

5 månader ago | 0

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Code is showing Undefined function 'pixelHull' for input arguments of type 'double'.

I wrote a function called pixelHull as part of my 16-Mar-2018 blog post. You can find the function listing near the bottom of th...

5 månader ago | 0

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Published

FFT Spectral Leakage

A MATLAB user recently contacted MathWorks tech support to ask why the output of fft did not meet their expectations, and...

5 månader ago

Binarize image for specific colour

Use the Color Thresholder app to generate the code needed to do this segmentation. See my 14-Oct-2019 and 25-Apr-2014 blog posts...

6 månader ago | 0

Plotting signal of a region of interest

A possible explanation is that you have a variable called "size" or "mean" in your workspace. For example, if you have a variabl...

6 månader ago | 0

How to apply a threshold value to the cell array

I think writing a for-loop would be most straightforward way to go. Something like this: for k = 1:numel(C) C_k = C{k}; ...

6 månader ago | 0

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How to change the font of a pie chart?

The text labels created by the pie function are not controlled by the font properties of the containing axes object. They are in...

6 månader ago | 2

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superimpose matrices (n,n,m) to (n,n,1)

Here are some options. Compute and plot the maximum value at each pixel: imagesc(max(a100,[],3)) Compute and plot the minimum...

7 månader ago | 0

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Image conversion from uint16 to uint8 mismatch

im2uint8 is using a scale factor of (255/65535), not 1/256. Note that scaling the maximum of the uint16 range, 65535, by 1/256 ...

7 månader ago | 1

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How do I map array values on a logical array

Use logical indexing. C = zeros(size(B)); C(logical(B)) = A

7 månader ago | 1

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Create a 7x7 convolution kernel which has an equivalent effect to three passes with a 3x3 mean filter.

Convolution is associative: So, your 7x7 convolution kernel would be the convolution of the mean filters: Use the 'full' o...

7 månader ago | 0

pgm image lossless compression

Write the image to a PNG file. The PNG format uses lossless compression. imwrite(A,'myfile.png') Read it back in using imread....

7 månader ago | 0

Published

How imshowpair and imfuse work

In this post, I'll explore how imshowpair and imfuse work.Reason: I was curious.Last month, I wrote about registering...

7 månader ago