Chapter 3 Digital Imaging
Advantages of using the vector graphic
1. Designed specifically for use on the web 2. created using HTML code 3. popular choice for mobile devices because of small sizes
Two ways to look at image sizes
1. File size or amount of storage space an image requires 2. Visual image
Bitmap images are measured in
2 ways
Print resolution size
300 ppi
Web resolution size
72 ppi
Pixelization
A condition of too-low resolution that allows individual picture elements to become visible.
Native file format
A file format that is unique to a program or group of programs and has a unique file extension.
Reducing images causes
A loss of sharpness
Lower resolution should be
used in email or posting to social networking. (72 ppi)
Different file types are appropriate for different situations?
yeth
Re-sampling
Adding or deleting image pixels during the process of resizing. - When re-sampling is on, changing the size of the image will not change the resolution but it will become larger or smaller. - Special formulas are used in re-sampling to determine what colors each new pixels should be, based upon the colors around it.
Professional raster program
Adobe Photoshop
The advantages and disadvantages of cloud computing
Advantage: access to software through the internet Disadvantage: may have a per-use fee
GUI
An acronym for graphical user interface. The GUI makes it possible to use a device, such as a mouse, to interact with a computer. - Apple Computer, Inc. marketed the first GUI (graphical user interface) programs as Mac-paint and Mac-draw.
256 colors
BMP, GIF
Four types of bitmap image extensions
BMP, GIF, JPG, PNG
Nonnative format
BMP, JPG, GIF, SVG, TIF, PNG, EPS
Nonnative Raster File Types
BMP, JPG, GIF, TIF, PNG
What are the most common raster file formats?
BMP, JPG, GIF, TIF, PNG
Large files
BMP, JPG, TIF : all quite thicc
Bitmaps
Bitmap images are made up from thousands of tiny dots called pixels (picture elements.) Programs such as Photoshop work with bitmaps. Bitmap images are similar to photographs; if you enlarge them too much, the image becomes grainy or pixilated.
Images are called
Bitmaps, Raster images, Raster graphics
changing the height without changing the width will result in _ of an image
Distortion
What kind of programs use vectors?
Drawing programs use vectors or line to produce an image. The vector are created using a series of mathematical points. Images produced by drawing programs called vector images
What are the most common vector file formats?
EPS & SVG
Nonnative Vector File Types
EPS, SVG
Transparencies/Animations
GIF, SVG, PNG
Colors best for web
JPG, GIF, SVG, PNG
16 million colors
JPG, SVG, TIF, PNG, EPS
Format Conversion
Once an image has been saved in its native format, you can change to another file type. - Select the drop-down box next to Format or Save as type box. - Choose from the list provided. - Different formats are for specific options: - Can import only graphics with specific formats - Some images look better in one format than another - Some need to be small for the Internet
Raster-Based Paint Programs
Paint programs create images by assigning each pixel to a point on a grid of x and y coordinates. The grid is called a raster. More commonly, these images are called bitmaps. - Raster graphics are used to create images such as photographs because of the wide range & variations of possible colors. - Enlarging raster images can result in pixilation, or jaggies (jagged edges). - Reducing images can also produce images that lose sharpness. - Examples of software programs that manage raster images: - Adobe Photoshop - most widely used program in professional world. - Microsoft Paint - provided with operating system. - Corel PaintShop Pro - stand-alone program that can be purchased separately. - GIMP - open source (free and works across wide range of computer platforms.) - Picasa or Flickr - cloud computing (access to software through the Internet), may be free or charge a per-use fee
Most images do not need to be small in order to load quickly on the internet
Phat false
Bitmap images have visual sizes measure in two ways
Physical size (ex: 640 x 480), Number of pixels in each inch (ex: 300ppi)
What two things help determine the file size?
Physical size and pixel density
_ is best on maintaining the aspect ratio
Resizing
Vector files
SVG, EPS
What are the most common extensions for the file formats that are typically used for Web use?
SVG, PNG, GIF
Pixel
Small squares (usually) with each pixel assigned a color, photoshop, consist of a specific color at a specific location in a matrix or grid. A collection of pixels produces an image on a computer screen or on a printed page. Used in Paint programs
Most programs cannot import graphics with specific file formats
Some can, some cant: False
Resolution
The density of pixels in an image or pixels per inch (ppi)
Pixel Dimension
The number of pixels in a row and column of a raster grid (ex: 640 x 480)
Compression
The process of reducing the size of the image
Aspect ratio
The ratio of the width to the height of an image. - When changing the width and height of an image, keep in mind the aspect ratio. - If you change one number without the other; distorted image. - Need to constrain the image
Bandwidth
The speed at which a computer can transmit information along a network.
Different file formats are appropriate for different situations
True
It's important as a Web developer that not everyone has high-speed connection.
True
Time it takes to download a graphic and display in a browser depends on file size and type of Internet connection.
True
Drawing programs
Use vectors, or lines to produce the image, Illustrator, lines are created using a series of mathematical points that can be changed without distorting the drawing.
What type of compression do GIF, PNG, and TIF use?
a lossless compression that doesn't change any pixels
Advantages of using a raster graphic
a wide range & variations of possible colors used to create photographs
Graphic file formats
are continually develop as new techniques and demands of business require them. - BMP - early format created without regard to file size - JPG - created as a result of the demand for fast download times on the Internet. - Flash - continue to evolve to providing animation & interactivity on the Web.
Why it is important to understand file extensions
because it indicates the file formats and that determines what programs open the file
Ways to reduce file image size
compression, resolution, resizing, and re-sampling
Lossless compression
does not change any pixel data
GIFs and TIFs are
lossless :)
JPGs are
lossy :o
Difference between lossy and lossless compression
lossy compression- reduces size by removing info that isn't essential lossless- doesn't change any pixel information
When re-sampling is _ changing resolution results in reduction of the image size
off
Image programs can be categorized into what two groups?
paint programs and drawing programs
determine the size of a file
pixel density
An image called 5"x7" is
pixel dimension (aspect ratio)
Enlarging raster images causes
pixilazation
Highest resolution should be used in
print. (300 ppi)
What is best done to maintain aspect ratio?
re-sampling
How are JPG images reduced?
reduced by using lossy compression algorithm that removes unnecessary pixels.
Lossy compression
reduces the size of an image file by removing information that is not essential
Why are images compressed
so they don't take up as much storage or so they can be stored more easily, it minimizes the size without degrading the quality
File Extension
the two to four letters following the dot at the end of a computer filename, picture.jpg (picture is the name of the file, .jpg is the extension) - The extension indicates the file format. This determines what programs open the file.