Warm up Question: More Questions Overview of Today's Topics
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1/27/2020 Warm up Question: More questions A. How big will a picture PRINT that was saved at 50DPI and is 200 pixels by 200 pixels? Convert the following binary numbers to B. If we have an image that was scanned in at 300dpi and was 2 inches by 3 inches, how many pixels will it be? decimal C. How many lines of text could you fit on a page given the ◦ 1001 9 following information? ◦ 0101 A. The font size in a MS Word Document is set to be 36 points. 5 ◦ 1010 B. We are using standard 8 ½ by 11 inch paper, portrait, with a 1 inch 10 margin at the top and a ½ inch margin at the bottom. ◦ 0011 3 C. The leading is 0 (no space between the lines). ◦ 1111 15 Answers: A. 4 inches by 4 inches B. 600 pixels by 900 pixels C. 19 lines Slide 1 of 55 Slide 2 of 55 Overview of Today’s Topics Announcements Sampling an image Computer Science 1033 – Week 4 Black and White, Gray and True Colour GRAPHICS YES, SIZE Indexed Colour DOES MATTER! Review and worksheet Bitmaps vs. Vectors https://www.linkedin.com/learni Image file size ng/affinity-photo-essential- training/working-with- Why we need compression selections?u=2152804 Afternoon, n.: That part of the day we spend worrying about how we wasted the morning. Unix Fortune Slide 4 of 55 Readings Announcements Textbook readings: This is the last time I can remind you to do ◦ Understanding Computers the syllabus quiz (due Jan 31) Files and Folders ◦ Graphics There will be consulting by t.a.s from Feb 2 – Basics of Graphics * Feb 4 in MC16a (see owl for times) Digitized Images * Let’s review the poster assignment File Size (first portion of Image Formats and Compression Techniques) The poster assignment is posted in Owl. Due Friday, Feb 7th at 3pm. ◦ * These two readings were suggested in previous weeks too. You don't have to read them if you did before! Sample of winning posters from last term and last year: and year before that and year before that Slide 5 of 55 Slide 6 of 55 1 1/27/2020 Hints on the marking of assignment Poster Assignment Tips Follow the instructions Check for spelling Follow the instructions carefully. Just by carefully, for example: Text: following the instructions, you can get a good ◦ you get 2 marks if you ◦ Contrast mark for this assignment! named your files as stated ◦ Edges Check that you have all the required criteria in the instructions! such as a shape from the shape tool. ◦ If you get a mark for every Images Check that you named all your files EXACTLY requirement we ask for. ◦ Crisp as we indicated. ◦ Appropriate DON’T Collapse your Make sure you picked good layer names layers Colours Remember to follow the CRAP rules! Name your layers with Professional looking Other tips good names – remember CRAP Colour Choices https://kuler.adobe.com/ and http://design-seeds.com/ Slide 7 of 55 Slide 8 of 55 Hints on Assignment Big Ideas for Today Use the shape tool to create: ◦ A shape, you can use the custom Big Idea 1: Mo bits per pixel … Mo Colors! shape tool ◦ Give the shape a good name, Big Idea 2: Bitmapped vs Vector: Thumbnail don’t collapse the layers Vectors Icons on the size of a bus? IT IS DOABLE! Big Idea 3: Mo bits, Mo problems! (The more bits you have to transmit, the slower your image will load unless you compress) Big Idea 4: Go Smaller or Go Compressing! Slide 9 of 55 Slide 10 of 55 Quantizing The Image Now that we know how many pieces our image How many colours can 2 bit hold? 22 4 will be broken into, how many colours will we ◦ 00 White have available to represent each pixel? ◦ 01 Light Gray Assume for each pixel we have 1 bit to represent the colour. ◦ 10 Dark Gray 1 bit can hold either 0 or 1 ◦ 11 Black ◦ 0 could be white ◦ 1 could be black Thus 1 bit allows for 2 colours, usually black and white (21 2) Slide 11 of 55 Slide 12 of 55 2 1/27/2020 Does 1 bit colour look realistic? 2 Bit Colour YES Can you tell what this image 4 shades of gray represents? Slide 13 of 55 Slide 14 of 55 How many shades of gray will 8 bits More bits, more shades of gray give us? 4 bit colour 24 16 Shades 0000 0001 0010 0011 1111 Slide 15 of 55 http://www.modernimaging.com/bit_depth.htm How about some Colour? Subtractive Model - CMYK Additive Model - RGB Used for printing Use on monitors Ink applied to paper “Adding” light to a black Primary Colours Cyan, background (the monitor) Magenta and Yellow Primary Colours Red, Ink when applied removes Green and Blue (subtracts) the white Slide 17 of 55 3 1/27/2020 How do we represent the colours 2 Ways to encode True Colours 1. <RGB> <amount of Red, True Colour amount of Green, amount of ◦ Can represent 224 colours about 16 million Blue> DECIMAL NUMBER different colours ◦ Where 0 is no amount and 255 is the ◦ 224 = 28 X 28 X 28 = 256 shades of red, X 256 most allowed shades of green X 256 shades of blue ◦ <255, 0, 0> the most of red, no green, no blue ◦ Need 3 bytes (remember: 1 byte=8 bits) for True ◦ <0, 255, 0> the most green, no red, Colour (1 byte for red, 1 byte for green, 1 byte no blue for blue) ◦ <100,100,100> equal middle amounts of red, green and blue ◦ <50, 0, 200> a little red, a lot of blue ◦ <200, 0, 50> a lot of red, a little blue Slide 19 of 55 Slide 20 of 55 Some hexadecimal colours: 2. Hexadecimal Code ◦ #RRGGBB RR are the digit place holders for the amount of red, GG amount of Green, BB amount of Blue ◦ Amounts are counted in hexadecimal with these digits: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F Question: Are these colours the same: ◦ 00 still means 0 • <0,0,0> and #000000? ◦ Hex FF= Decimal 255 (try the calculator to see) • <0,0,0> and #000000? ◦ Hex to Dec 00=0, 01=1, 02=2, 03=3, 04=4, 05=5, 06=6, 07=7, 08=8, 09=9, 0A=10, 0B=11, 0C=12, 0D=13, 0E=14, 0F=15, • <9,8,7> and #090807 10=16, 11=17,….. FD=253, FE=254, FF=255. •<10,15,09> and #__0A __0F 09 ◦ #FF0000 Red • <255,0,255> and #FF00FF ◦ #00FF00 Green • <255,0,255> and #FF00FF ◦ #000000 Black • <66,0,99> and #660099 ? ◦ Question: what is the hex for WHITE? • <66,0,99> and #660099 ? NO http://easycalculation.com/color-coder.php http://easycalculation.com/rgb-coder.php Slide 21 of 55 Can you represent the same number How many colours do we need to of colours using Hex as using RGB encode? YEShttps://www.rapidtables.com/convert/number/hex-dec-bin-converter.html Red Green Blue How many colours? QUESTION: Roughly, what is the Smallest Value (RGB) 0 0 0 maximum number of colours the Biggest Value (RGB) 255 255 255 Total number of shades 256 256 256 256X256X25616 human eye can detect? you can represent million colours Smallest Value (Hex) 00 00 00 BiggestValue (Hex) FF FF FF ◦ Less than 10 million Total number of shades 16X16 16X16 16X16 28 X28 X 28 22416 you can represent 24X2428 24X2428 24X2428 million colours Smallest Value (Binary) 00000000 00000000 00000000 BiggestValue (Binary) 11111111 11111111 11111111 Total number of shades 2X2X2X2 2X2X2X2 2X2X2X2 28 X28 X 28 22416 you can represent X2X2X2X X2X2X2X X2X2X2X million colours 228 228 228 Slide 23 of 55 Slide 24 of 55 4 1/27/2020 Colour Continued…Indexed Colour (not true colour) Indexed Colour Sometimes we don’t need 16 million colours, then Indexed Colour can look pretty good even we use indexed colour (an index that maps to a though we will only ever have at most, 8-bit group of colours we plan to use) colour (or 256 shades of colour) QUESTION: What types of images don’t need a full palette of colours? Our index might be 8-bits 28 different colours (just like with gray shades) thus we can show 256 different colours. Called the Image Bit Depth, e.g. 8 bit depth We only index the colours we needWhy do(if thewe bottomwill never boxes appear to have use purple in our image, don’t needno colours to include in them? it in the index of colours) http://www.csd.uwo.ca/~lreid/cs033/BitDepth/ Slide 25 of 55 Slide 26 of 55 Review: Review Sheet Match the encoded colour to the correct Work on the review sheet for about 5 colour name: minutes (alone or with a friend) and we will Encoded Colour Colour Name Encoded Colour take it up as a group. a) #FFFFFF 1. White a) #FFFFFF b) #00FF00 2. Black b) #00FF00 c) #FAFAFA 3. Dark Gray c) #FAFAFA d) (0,0,255) 4. Light Gray d) (0,0,255) e) (0,0,0) 5. Medium Gray e) (0,0,0) f) (14,14,14) 6. Bright Green f) (14,14,14) g) (125,125,125) 7. Bright Blue g) (125,125,125) Slide 27 of 55 Slide 28 of 55 BREAK Bitmapped Images vs. Vector Graphics Link sent to me by one of our students, cool Bitmapped Graphic Image photoshop video: ◦ Image consists of pixels in a grid ◦ http://www.youtube.com/watch?v=53m0syaPg9A& ◦ Icons are an example of a bitmapped t=0m39s image (do you recognize this icon? ) Icons are usually 32 pixels by 32 pixels Video created by a high school kid from ◦ When bitmapped images are enlarged Stratford Ontario(took him 2 years): (resampled), the computer adds new pixels ◦ http://www.youtube.com/watch?v=qIuxiwhUGz4 and guesses on the colour to colour the new pixels (called interpolation) based on surrounding pixels ◦ This icon is now 245 pixels by 245 pixels ◦ Bitmapped images edges become jagged Slide 29 of 55 Slide 30 of 55 5 1/27/2020 Bitmapped Images Common Bitmap Formats Also called raster graphics image Common bitmap file formats are: ◦ BMP (has little compression, makes big files!) Bitmapped images are resolution ◦ GIF ◦ JPEG, JPG dependent ◦ PNG ◦ Bitmapped image on a 640 by 480 ◦ PICT (Macintosh) screen (lower resolution) appear ◦ PCX larger than on a 1280 by 1024 screen ◦ TIFF ◦ AFPHOTO (Affinity Photo) (higher resolution) ◦ PSD (Adobe Photoshop) Bitmapped images that are Popular bitmap editing tools/software packages: ◦ Microsoft Paint enlarged: ◦ Adobe Photoshop ◦ Have larger file size than original ◦ Affinity Photo ◦ Corel Photo-Paint ◦ Become distorted ◦ Corel Paint Shop Pro All images from scanners and digital ◦ The Gimp cameras are bitmapped images Slide 31 of 55 Slide 32 of 55 Vector Graphics Vector Graphics As image is enlarged, still has crisp clean lines.