# Blog Arşivleri

## Edge Detection on Matlab

Hi everyone,

At my this project i am going to make edge detection. I will use matlab’s built in functions.

This is my original photo. I will read it, convert to the gray, finally from the gray photo i will detect the edges.  As you can see from the code below, i used sobel edge detection.

```lena=imread('lena.jpg');
lena_gray=rgb2gray(lena);
lena_gray_double=double(lena_gray);
lena_gray_double=lena_gray_double/max(max(lena_gray_double));
figure;
edge(lena_gray_double,'sobel')
title('Built-in Edge Detected Image With Sobel');
%https://ozturkgokhan.com/
```

Best wishes;
Gökhan ÖZTÜRK

## Plotting Equation at Z-Plane

```Hi, today i will try to plot poles and zeros of an parametric equation.
A parametric equation type is given below b(n) and a(n) are the coefficients
of the equation

Assume we know the  coefficients. Let's try to plot at z- plane.

```
```b1=[1 -0.4944 0.64];
b2=[1 0.4944 0.64];

root_a1=roots(a1);
root_b1=roots(b1);

figure;zplane(root_b1,root_a1);
title('Pole-Zero Diagram of a1-b1 System');
%http://ozturkgokhan.com
```

As u see we managed the process.
Best wishes;
Gökhan ÖZTÜRK

## Making Downcounter at App Inventor 2

Hi everybody,
Now i will try to make downcounter at app inventor2.
In this application we will use it and we will create a downcounter.

We will use clock, button and label component.

When we push the start button, a counter will start to count from ten to zero..

I defined a variable named “value1” that has the value of ten. At the beginning -when screeen initialized- clock is disabled. When we push the button, value of the “value1” will decrease one-by-one until it reaches to zero. When the counter’s value is zero, button’s text will change to “finished”. Then it will wait for another input as pushing.

Best Wishes,

Gökhan Öztürk

## Usage of Slider Component at App Inventor 2

Hi, my second post will be about usage of slide component at app inventor 2.

Slider is a component that its value change by the position. We can define the max. and min. value.

I took a label and slider from user interface and put them in to a VerticalArrangement that taken from layout.

When we change the slide its value will change and then label will change. If the thumb position is lower than 25 label will be “b” and if the thumb position is higher than 25 label will be “a”

Program output at screen.

best wishes,

gökhan öztürk