Weeks 3 and 4 Flashcards
(166 cards)
1
Q
how many colours can 2 bits hold
A
2^2 = 4
2
Q
if an image is 400 by 300 pixels, and we use 1 byte of colour for each pixel, what is the file size
A
400x300x1byte = 120000 or 120 kilobytes
3
Q
1 kilobyte is how many bytes
A
1000 bytes
4
Q
is an image is 400 by 50 and uses 1 byte of colour, what is the file size
A
2000
5
Q
What is the Subtractive model for colour used for
A
printing - ink applied to paper
6
Q
what colours does the subtractive model have
A
cyan, magenta and yellow
7
Q
how does the ink work in a subtractive model (in terms of white
A
ink when applied removes the white
8
Q
what is the additive model used on
A
monitors
9
Q
how does the additive model for colour work
A
adds light to a black background (unlike subtractive model which removes white by adding colour to the page)
10
Q
how many colours can True Colour represent
A
2^24 or around 16 million different colours
2^8 = 256 shades of red
2^8 green
2^8 blue
11
Q
how many bytes are needed to represent true colour
A
3 bytes - 1 byte for each colour (rgb)
12
Q
what are the two ways to represent true colour
A
RGB - amount of Red, amount of Green, amount of Blue>
uses DECIMAL NUMBER system
and Hexadecimal
13
Q
<255, 0, 0>
A
all red no green or blue in rgb true colour
14
Q
0 in RGB represents
A
no colour
15
Q
255 in RGB represents
A
most colour allowed
16
Q
<0, 255, 0>
A
most green rgb true colour
17
Q
<100,100,100>
A
middle amounts of rgb - gray
18
Q
<50, 0, 200>
A
little red, lot of blue, dark blue
19
Q
<200, 0, 50>
A
little blue lot of red
dark red
20
Q
how is hex colour represented (what digits and format)
A
#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
21
Q
09 in hex is
A
9
22
Q
0B in hex is
A
11
23
Q
0F in hex is
A
15
24
Q
FF in hex is
A
16^115+16^015 = 255
NOT 15*15
25
how to determine hex digits
multiply each digit by 16^(the digit's placehoder)
26
#FF0000
red
27
#00FF00
green
28
#000000
black
29
#FFFFFF
white
30
<0,0,0> in hex
<0,0,0> and #000000?
31
<255,0,255> in hex
and #FF00FF
32
<66,0,99> in hex
#420063
33
#43B390 in rgb
<67,179,144>
34
#0A0F09
<10,15,09>
35
what is an example of when you need fewer colours
clipart
36
what is an example of a bitmapped image
an icon (firefox)
37
how large are icons usually
32x32 pixels
38
what is interpolation
when the computer adds new pixels and guesses on the colour to colour and the new pixels
39
when does interpolation happen
when images are enlarged (resampled
40
what happens to the image itself and the file size when you enlarge an image
it becomes larger file size and the bitmapped edges become jagged and the image becomes distorted
41
all images from ___ and ___ are bitmapped
scanners and digital cameras
42
what is another name for bitmapped images
raster graphics
43
bitmapped images are___ dependent, meaning
resolution dependant meaning that a bitmapped image on a lower resolution screen will appear LARGER than on a higher resolution screen
Bitmapped image on a 640 by 480 screen (lower resolution) appear larger than on a 1280 by 1024 screen (higher resolution)
44
what are common bitmap formats
```
BMP (has little compression, makes big files!)
GIF
JPEG, JPG
PNG
PICT (Macintosh)
PCX
TIFF
AFPHOTO (Affinity Photo)
PSD (Adobe Photoshop)
```
45
what are popular bitmap editing tools/software packages
```
Microsoft Paint
Adobe Photoshop
Affinity Photo
Corel Photo-Paint
Corel Paint Shop Pro
The Gimp
```
46
what is a vector image made up of
individual scalable objects
47
what are the objects in vector graphics definded by
mathematical equations
| objects consist of lines, curves and shapes...
48
are vector graphics distorted as the image is enlarged?
no
49
do most browsers display vector graphics?
Most browsers don’t display vector graphics without a plug in
50
vector graphics can only be used with __ not __
drawings not photographs
51
what is an example of a file type that is uses vector graphics
pdf
52
do vector graphics have smaller or larger file size than the same img stored as a bitmap?
Usually vector graphic image has a smaller file size than the same image stored as a bitmap.
53
it is __ to turn a vector into bitmapped and ___ to turn bitmapped into a vector
easy, hard
54
what are vectors great for
logos because
Can be scaled down for business card
Can be scaled up for a trade show poster
55
what are some common vector file formats
```
AI (Adobe Illustrator)
CDR (CorelDRAW)
CMX (Corel Exchange)
CGM Computer Graphics Metafile
DXF AutoCAD
WMF Windows Metafile
EPS (Encapsulated PostScript)
PDF
```
56
what are popular vector drawing programs/software packages
```
Adobe Illustrator
Affinity Designer
CorelDRAW
Xara Xtreme
Serif DrawPlus
```
57
how to calculate the size of an image
Sampling*quantize
Length (px) * width (px) * Colour bit depth(bytes)
total pixels (sampling) *Colour Bit Depth(Quantize)
58
too many colours/too large a file size will cause what in terms of your webpage
it will take ur webpage too long to load and therefore people might leave right away
59
1KiloBytes =
1000Bytes (1024 but 1000 for exam)
60
1 Megabyte =
1000 kilobytes
61
1 gigabyte =
1000 megabytes
62
1 terabyte =
1000 gigabytes
63
what is the byte higherarchy
bit - byte - kilobyte - megabyte - gigabyte - terabyte
64
When printing in a flyer/ magazine, what matters/ does not matter
file size does not matter
| quality of the image matters
65
what is the smallest dpi at which the image must be printed
300 dpi
66
for displaying an image in a webpage what is important/not important
file size is important and so is quality but you want to get best quality with smallest file size because bigger file = longer download
67
what are two ways to make the image file size smaller
compress the image (using tricks to make the file size smaller without making the img lower quality) or make the image smaller (less pixels but changes the size)
68
what does the download time depend on that you cannot control
client's connect speed
| that you cant control
69
what are the two types of compression
lossless
| and lossy
70
what is lossless compression
NO INFORMATION IS LOST
Compress the original bits and bytes into less bits and bytes without losing any of the original information about the picture
so when reopen the file, all the original information about the picture is still there!
71
what is lossy compression
Selected portions of the image are discarded but the selected portions are the ones that will be the ones that least missed or noticed
CANNOT GET THIS INFO BACK ONCE IT IS DISCARDED
72
each different type of image file format represents...
the use of a different compression algorithm
73
common compressed image file formats that are acceptable on the world wide web are
gif, jpg/jpeg, png
74
uncompressed file formats
bmp (windows)
| raw (common digital cameras)
75
Select the valid RGB colour code that would best represent a shade that the water colour might be on a tropical island (e.g. a turquoise type colour).
A. (200, 200, 5)
B. (150, 150, 150)
C. (4, 199, 199)
D. (0, 302, 302)
E. Both C) and D) are valid shades of colours you might see for the water at a beautiful tropical beach.
C
| d does not have valid numbers
76
```
Select the hexadecimal colour code(s) that represent valid shades of gray (check all that apply).
A. #252525
B. #330333
C. #4g4g4g
D. #9a9a9a
E. #720720
```
A, D
| c does not have valid digits
77
(5, 3, 218) in hex is
blue
78
#ee0000
red
79
(64, 0, 0)
dark red
80
(56, 56, 56)
dark gray
81
#c5c5c5
light gray
82
If there are boxes with "X" in an Indexed Colour image palette, that means:
A. the image has too many colours and some will have to be modified
B. some of the colour shades in the image are too similar
C. the image does not require as many colours as the palette can support so the image won't save properly
D. the image does not require as many colours as the palette can support and this is perfectly acceptable
D
83
Indicate which of the following statements is NOT true about vector graphics.
A. Vector graphics are defined by mathematical shapes and curves.
B. Vector graphics are clear for images that contain up to 8 colour shades, and blurry in images with higher numbers of colour shades.
C. Vector graphics can be made at any size and later enlarged or shrunk as needed without loss of quality.
D. Vector graphic files usually have a smaller file size than the same image stored as a bitmap.
B
84
An image is 2*000 pixels by 1*000 pixels and is true colour. The filesize of this image is ___ bytes.
6000000
85
```
There is an image that is 2.3 MB. What is the approximate number of kilobytes in this image?
A. 0.0023
B. 2
C. 2300
D. 2300000
```
2300
86
```
A printed image, that is 3 inches by 4 inches, is scanned into a computer with 100 DPI as true colour. Calculate the approximate filesize of this image, assuming no compression is done.
A. 120 kilobytes
B. 0.36 gigabytes
C. 0.36 megabytes
D. 360 megabytes
```
360,000 bytes --> 360 kilobytes --> 0.36 megabytes
87
true or false Lossy compression will remove some of the original information stored for an image. That information/level of quality can never be retrieved again after the compression.
true
88
Indicate which of the following options are needed when connecting to a server using FTP or SFTP .
```
A. Username
B. Host/server name
C. Port number
D. Password
not theurl that you type into the browser address bar
```
89
```
Indicate which of the image formats is based on biological discoveries related to the human eye (check all that apply).
A. JPG
B. PNG-8
C. PNG-24 / PNG-32
D. GIF
```
JPG
90
The number of bits needed to store the word queen in ASCII is __ bits.
Using the Huffman Code chart shown in class, storing queen in Huffman would take __ bits.
40
| 26
91
Indicate which of the following statements are true (check all that apply).
A. GIFs support up to 256 colours.
B. GIFs do a great job when representing a gradient, such as the orange and red and yellow colours blending into each other in a sunset.
C. GIFs use a lossy compression.
D. GIFs can be dithered to create the illusion of additional colours in the image
A and B
92
GIFs can be saved such that the image will appear in a series of passes with alternating lines of pixels loading, and the gaps being filled in later on. This process is called____.
interlacing
93
Which of the following statements are true? (check all that apply)
A. JPGs and GIFs support dithering, but PNGs do not.
B. JPGs do interlacing.
C. JPGs allow for animated images.
D. There is software that saves an image as a JPG and will allow you to control the amount of compression/loss of quality.
D
94
JPGs are not good for images with clean crisp lines.
True
False
true
95
Indicate which of the following statements are true (check all that apply).
A. All PNGs support full transparency.
B. PNG-8 supports up to 256 colours.
C. PNG-32 supports up to 2^32 (2 to the exponent 32) colours.
D. In the 90s, PNGs were licensed so users had to pay a small fee (1-2 cents) each time they created a GIF.
B
| for D it’s the opposite, PNG’s we’re created due to licensing issues with GIF
96
PNGs were created as a response to licensing issues with __ in the 90s.
gif
97
We inserted 2 different images of a girl onto a powerpoint slide as shown below. What do you know for sure about the image under the text Girl B?
(transparent background)
A. The image under the text Girl B must have been stored as a JPG
B. The image under the text Girl B must have been stored as a PNG or GIF
B
98
Indicate which of the following statements are true (check all that apply).
A. PNG-32 support full transparency.
B. PNG-8 only supports 8 colours
C. PNGs were created in response to licensing issues with GIFs in the 90s
D. ALl PNGs use lossless compression
ACD
99
What does SFTP Stand for
Secure File Transfer Protocal
100
What does SFTP do
It moves files from 1 location to another (computer - web server)
101
What is a web server
A computer that sends or serves up web pages
102
What are some advantages of a web server
Connected, always available and well maintained
Connected - computer is on all the time and connected to the internet
Always connected Elena’s that it since will never get turned off your website will always be available
Well maintained - the people running the server will take care of security and computer maintenance issues
103
What is a client
Computer requesting to visit the web page
104
What is are some examples of a fiile transfer program
Firezilla or WinSCP
105
What code makes a file transfer program thing available to the internet
0755
106
What does RAW mean in terms of compression
RAW has no compression at all meaning that it is a large file
It stores info about each pixel one at a time
An image that is 100 by 200 pixels that is RAW will store 60000 bytes of information
107
What is a strategy for using colour to compress an image
You can break image into parts where you assign each part to a certain colour
This would be lossless
This strategy is best with regular shapes (in reality gif compressions are a lot more complicated
108
What is another way to compress an image other than assigning each part a colour
Looking for patterns and making a decoding hash table eg
0=1234
1=19999
2=3332
Compressing words - texts in a dictionary ASCII
109
How is ASCII code represented in terms of bits
Each letter is represented using 8 bits or 1 byte
110
What is Huffman Coding (compare to ACII)
Rather than ASCII (each letter is 8bits or 1 byte) use the least number of bits for common letters and more bits for less common letters
111
What did the designer of JPEG compression algorithm realize about the human eye
That the human eye is more sensitive to brightness details than to fine color details.
112
How does the JPEG compression algorithm work
If it finds two adjacent pixels with very similar colors, it will store both those pixels with the same color and discard the other color.
113
What are the three file formats we will look at
GIF
PNG
JPG
114
What determines the best file format for an image
The type of image that we are trying to compress will best determine the best file format to use
115
What does GIF stand for
Graphic INterchange format
116
GIFS work cross platform t/f
True
117
GIFS are widely used across the World Wide Web t/f
True
118
What amount of colour do GIFS support
8 bit colour
119
What are GIFS good or not good for
Good for clip art logos animations
| Not good for photos or like paintings
120
How do GIFS work
They look for large blocks of area that all have the same colour
121
Saving an image with 24 bit colour as a gif will do what to the quality
It will lower the quality the first time you compress it
122
Are gifs lossy or lossless
Lossless
123
Do Gifs allow for transparency?
Yes - one colour transparency, meaning it allows for transparency of one colour
124
What is one colour transparency and what kind of file format allows for it
Allows for transparency on once colour and GIFS allow for this
125
How does animation work with gifs
Allows for animation
Don’t need a plug in for gif animation!
Works in all browsers, universal format!
126
What is dithering
Putting two colours next to eachother to create illusion of another colour
Dithering is the process of juxtaposing pixels of two colors to create the illusion that a third color is present.
127
Do gifs allow dithering
Yes
128
Gifs do not allow dithering
No, gifs do allow dithering
129
How do gifs use dithering
If ur image has more than 256 colours, it uses dithering
In a gif, you can reduce the number of colors in a GIF and choose options to control the way colors dither in the application or in a browser.
130
What is interlacing
process by which the image is drawn in a series of passes rather than all at the same time (file size bigger)
131
Do gifs use interlacing
Yes
132
Why use interlacing
Interlacing lets you have a feel for the whole picture, you don’t have to wait around to see it download (good for dial up connections)
133
How do gifs use compression
By reducing the number of colours in the image
134
What does JPEG stand for
Joint Photographic Experts Group
135
Where are JPGs used
Widely used on the World Wide Web
136
Are JPG cross platform?
Yes works on Mac , windows
137
How many bits of colour do JPGs support
24 bit colour
| 3 byte
138
What are jpgs good for
Photos, computer games, screenshots, stills from a movie etc
| Best blends of colour, softer shadow effects, subtle changes in colour
139
What are jpgs not good for
Well defined lines or sharp changes in colour
140
Is JPG lossy or lossless
Lossy
141
What kind data does the jpg discard
Because jpg is lossy it discards more data about colours than about brightness
Onto all info in original image is preserved
142
do JPG degrade the image quality
yes
143
How does JPG compression work
Compression is achieved by ‘forgetting’ certain details about the image, which the JPG will then try to fill in later when it is being displayed
144
can you control the amount of info lost in a JPG compression
Degree of amount of information LOST (lossyness) can be varied by adjusting compression parameters. (controlled by you)
145
quality of image is _____ to the amount of compression
Inversely proportional
| A higher image quality setting (has a lower compression value) results in less data being discarded.
146
can a JPG use dithering
no because you have the full palette, so no need to combine colours
147
can a JPG use interlacing
no (recall that interlacing gives u the gist of the image before download finishes)
148
can a JPG do Animation
no
149
can a jpg have transparency
no
150
why were PNGs created
Created specifically because of licensing issues with GIFs in the 90s
151
what kind of compression does PNG use
lossless
152
what are the three versions of png
png-8, png-24, png-32
153
how is png pronoucned
PING
154
PNG-8 are similar to ___ in what ways
allow 25 colours and one transparent colour, lossless
155
how are PNG-8 and ___ similar
Storing of colours is more efficient in PNG files than GIFS thus PNG-8 files might be SMALLER than their GIF counterparts (this is software dependent)
156
PNG-24 and PNG-32
allow for 24 bit colour
allow different levels of transparency (good for shadows) and allows for transparency on each pixel
however only png 32 allows for a full pallette of colour AND transparency. if you want varying levels of transparency with PNG-24, you will lose some colour
157
PNG-24 and PNG-32 will almost always have a ___ file size than a JPG
larger - jpg = lossy while PNG are lossless
158
difference between PNG-24 and PNG-32
PNG 32 allows for a full palette with full transparency but with PNG 24 if you want varying levels transparency, you will lose some colours
159
Type of compression for each file type (GIF, JPG, 3PNGs)
```
gif = lossless
png = lossless
jpeg = lossy
```
160
GIF, JPG, 3PNGs are well supported in which browsers
GIF, JPG, PNG-8 all browsers
| png-24, png-32 = not on IE6
161
transparency allowed in each file type
```
gif = one colour only
jpg = no
png-8 = one colour
png-24 = varying levels of opacity and transparency with loss of colour that comes with it
png-32 = full transparency with no loss of colour
```
162
what each file type is best for
gif, png-8 = logos, cartoons,, drawings and animations for gifs but not png
jpg = photo
png-24, png-32 = photograph images with a need for transparency
163
which file types allow animation
gifs only not png or jpg
164
which file types do dithering
png 8 and gifs
| not png24 or 32 or jpg
165
which file types do interlacing
gifs and png 8
| not jpeg or png24 or 32
166
what are the requirements for the shape of the image for each file type
jpg must be rectangular
