Ankur Pratap

The Retina Display

September 19, 2012 by Ankur Pratap 2 Comments

Retina display is a term coined by Apple Inc. to describe display device specification having a pixel density such that the human eye fails to distinguish between two adjacent pixels in a pixelated image.

Every image that we see on a modern display device is pixelated. Pixels can be thought of as fine dots which when collected together make the image complete. For example, when we draw a line, thousands of pixels follow each other in a straight pattern to make up the line. The pixel density, the size, the intensity of display all depend upon the architecture of the underlying hardware of the device. To display a pixel, the parameters of a pixel like the colour, the intensity are varied according to different algorithms like Bresenham’s line drawing algorithm, DDA algorithm, Xiaolin Wu’s line algorithm and many more advanced algorithms. To display the colour, different colour models like the RGB, CMYK are used. [Read more…] about The Retina Display

Touchscreens: Resistive vs Capacitive

September 16, 2012 by Ankur Pratap 2 Comments

Since the advent of touchscreens in the late 1960’s touchscreens have undergone myriad number of advancements. From scratch-resistant screens to ultra-sensitive ones, these interfaces just speak volumes about the way technology has evolved.

Touchscreens come in two variants: Resistive and Capacitive. The nomenclature reflects the working of the two varieties. Resistive touchscreens were the first ones to be used on smart phones and tablets, though they are not out-dates ones now.

Here is a comparison of the two popular technologies used in building a touchscreen. Though it is not an absolutely perfect guide, it will give you an idea of which one is better in which parameter.

Parameter	Resistive touchscreen	Capacitive touchscreen
Age	Relatively older technology	Newer technology
Accuracy	More	Less accurate, requires special stylus for better point detection
Durability	More	Less
Clarity	Less in normal daylight	More due to use of less number of layers
Responsiveness	More pressure requirement makes it less responsive	Though it is more responsive, it is less durable and hence requires more pressure as it gets older
Cost	Lower	Higher
Touch accessory	Any pointed object will work fine	Special stylus is required for better operability. Many modern touchscreens do not work if any objects other than human fingers are used.
Typical working temperature	Works best between -15℃ to 55℃	Works best between 0℃ to 35℃
Robustness	Though a resistive screen is responsive to any kind of pointed device, it has a vulnerability to force by pointed objects. More force will eventually make it difficult to use. However, it is sturdy enough to sustain the adverse effects of a fall	As the outer layer is made up of glass, it is resistant to scratches and is easy to clean. However, it is vulnerable to the shattering effect of a fall.

These observations have been compiled over a study of various sources including people, web sites, journals. Please feel free to share your views and experiences.