# How to find minimum and maximum pixel value in image

41 views (last 30 days)
Med Future on 19 Mar 2022
Commented: Med Future on 21 Mar 2022
Hello Everyone, i hope you are doing well.
I have the following to images. i want detect the pattern and find the minimum and maximum value for the pattern
for example the first image sinewave. i want to detect the shape and find the value for upper peak and lower peak.
same for the second image
Can anybody help me in that
Med Future on 20 Mar 2022
@Image Analyst Can you please check this

Atsushi Ueno on 19 Mar 2022
Edited: Atsushi Ueno on 20 Mar 2022
>i want detect the pattern and find the minimum and maximum value for the pattern
The images have black background with value 0 and a white line with value 255.
You can use max(org:find) function to find non-zero value in each columns in the picture data.
[~, wave] = max(image); % thx @Scott MacKenzie for x = 1:size(image,2) wave(x) = find(image(:,x)); end
max(wave) % It is y coordinate value of each dots on the white line.
ans = 991
min(wave) % It is y coordinate value of each dots on the white line.
ans = 981
plot(wave);
DGM on 20 Mar 2022
What exactly do you mean when you say "detect the shape"?
Do you want a mathematical expression of the periodic function?
Do you want to classify the type of periodic waveform?
Are you trying to find instances of the same (or similar) shape in other images?
If you want the first one, note that nothing in these images conveys any calibration information. All units will be in pixels. You will need to know the relationship between image coordinates and data coordinates.
Med Future on 21 Mar 2022
@Atsushi Ueno@_ @Scott MacKenzie @DGM Thank for you answer. First step to find minimum and maximum of the value which is done using above code.
I also want to detect shape for example in periodic waveform im_003002.png the cycle repeat 6 times , i want to detect if any image comes how many cycles are there in the waveform

### Categories

Find more on Image Segmentation and Analysis in Help Center and File Exchange

R2021b

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!