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.