How touch screen works?

 

Resistive Touch Screen
The resistive touch screen resists your touch literally and if you press harder you can feel the screen bent slightly. This is what makes the resistive touch work. There are two layers in the resistive touch, the resistive layer and the conducting layer. These are separated by tiny dots called spacers. The electric current flows through the conductive layer at all times but when you touch the screen i.e. resistive layer, it comes in contact with the conducting layer. Thus the electric current changes at that point and the function corresponding to that point is carried out.

 

Capacitive Touch Screen
The capacitive touch screen does not use the pressure of your finger for the flow of electricity. Instead, they work with anything that holds an electric charge, including human skin. They are made from materials like copper and indium tin oxide that hold electric charges in an electrostatic grid of wire each smaller than a human hair. There’s a glass substrate,a conductive layer , a protector, a controller and electrodes at the corners. The electrodes apply a low voltage to the conductive layer to form a electrostatic field. When a finger hits the screen, a tiny electrostatic charge is transferred to the field that completes the circuit. A voltage drop is created at that point. The location of the voltage drop is reported by the controller. And this is how a capacitive touchscreen works.

 

What is hydraulic pressure?

Hydraulic pressure is a force that exerted by a liquid onto a confined surface. When it is applied on a fluid in any confined area, the force is transmitted in all directions by the fluid leading the system to its operation. It is more powerful than pneumatic or mechanical pressure, due to which it is used in applications dealing with greater loads. A pressure guage is required to measure the pressure of the fluid. The formula to calculate hydraulic pressure is F = PA, where, F = force, P = pressure and A = area.

 

Calculation of the centre of mass of an image

Example of calculation of the centre of mass of an image. (a) The original square image; (b)
A 12 x 12 (pixellated) version of the image so that the calculations are simpler to see (although for
the images proper in the study all pixels are used from the entire image); (c) The calculations. The
12 x 12 matrix shows the darkness or weight of each pixel (ie, 255 = black = heavy; 0 = white = light).
The table at the bottom show ri, the arbitrary horizontal distance of each pixel from the left-hand
side, expressed as pixel number, the summed mass of each column of pixels, mi, and the product of
mi and ri (mi.ri). At the end of each row are the sums of ri and mi.ri, which are used to calculate R,
the position of the centre of mass, which is at 6.1 pixels from the left-hand side. The table at the
right shows the equivalent calculations for the rows, with ri arbitrarily being the vertical distance from
the top row of pixels. The centre of mass for the image as a whole is 7.4 pixels from the top and 6.1
pixels from the left, and those positions are shown by the red and green dashed lines in (b), with the
intersection, shown by the white circle, being the centre of mass of the image.

 

Implementation of 2D to 1D Array Formula in Image Processing

public void Invert(ref Bitmap bmp)
{

BitmapData newData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height),
ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

int total_size = newData.Stride * newData.Height;
byte[] g_PixBytes = new byte[total_size + 1];
byte[] g_OutBytes = new byte[total_size + 1];

Marshal.Copy(newData.Scan0, g_PixBytes, 0, total_size);

 

for (int y = 0; y < bmp.Height; y++)
{

for (int x = 0; x < bmp.Width; x++)
{

int pix = y * newData.Stride + 3 * x;               //2D to 1D Array Formula

g_OutBytes[pix + 2] = (byte)(255 – g_PixBytes[pix + 2]);
g_OutBytes[pix + 1] = (byte)(255 – g_PixBytes[pix + 1]);
g_OutBytes[pix + 0] = (byte)(255 – g_PixBytes[pix + 0]);
}
}

Marshal.Copy(g_OutBytes, 0, newData.Scan0, total_size);

bmp.UnlockBits(newData);

g_PixBytes = null;
g_OutBytes = null;

}

//Simple image invert filter by C# programming language.

2D to 1D Array

 

-2D(Width, Height) to 1D Array Formula = Y * Width + X

-Example of a 2D array with size:
Width = 20, Height = 50
-Example position(X, Y) in this array:
X = 15
Y = 35

-Representing this 2D position by a 1D Array:
–> Y * Width + X
–> 35 * 20 + 15
–> 715

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