Week 1 - Friday CS 113

Last time What did we talk about last time? Syllabus and course policies A little bit about computers

Questions?

Graphics

Screens Ultimately, most graphics that we're interested in on a computer are displayed on a screen A screen is made up of dots Each dot is called a pixel, short for picture element Each pixel has a color By displaying enough pixels, you can make a picture

Resolution A screen has both a width and a height in pixels The combination of these is called the resolution of the screen Higher numbers mean more pixels, allowing a more accurate representation of images Device Resolution iPhone 4 960 x 640 iPhone 6 1334 × 750  Older monitor 1024 x 768 720 HD TV 1280 x 720 1080 HD TV 1920 x 1080 4K monitor 3840 x 2160

Aspect ratio It's difficult to create programs and video content that looks good on any arbitrary screen size Many screens have one of three different aspect ratios (the ratio between width and height) Why are there three different ones? Aspect Ratio Example Devices 4 : 3 1024 x 768 Standard definition TVs, older monitors 16 : 9 1920 x 1080 High definition TVs, many newer monitors 16 : 10 1280 x 800 Some newer monitors

Buying a TV Many of you will buy a TV (or a monitor) at some point HD TVs will all have a 16 : 9 aspect ratio A 1080 TV has more than twice as many pixels as a 720 TV Contrast ratio is the ratio between the brightest (maximum white) and the darkest the screen can show A higher contrast ratio makes a more vibrant image There are 1080p and 1080i TVs (similar for 720) p is for progressive and i is for interlaced Interlaced is an old standard based on how TV signals used to be sent Progressive is clearer and easier to look at, especially for text

Working with graphics In order to program graphics in a computer, we'll have to think about the screen (or some part of it) as a Cartesian coordinate system In some systems, y starts at 0 at the top of the screen and increases downward In other systems, y starts at 0 at the bottom of the screen and increases upward x y (0,0) x y (0,0)

Scratch For the first few weeks of the semester, we'll be using Scratch to program with Scratch puts x and y in the middle, with positive and negative values, like a normal Cartesian plane x y (0,0)

Scratch Tutorial

Lab 1

Upcoming

Next time… Back to computers More on graphics We will start 3D graphics

Reminders Pick your teams for Project 1 if you haven't already!