What to represent images. Whereas, the other way

What are they made from?

Bitmap graphic are made
from many tiny parts, called pixels, they are often in many different
colours. You can edit individual pixels. The computer stores information
about every single pixel in the image, therefore the file size is often quite
large. Pixels containing a value
that represents the conditions for the area are covered by that cell.

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How well do they scale?

Bitmaps are
resolution-dependent, this means that if the bitmaps are scaled up, the
pixels become more visible and the quality of the graphic compromised. Therefore,
as the picture enlarges, it tends to lose quality. The scale of a bitmap depends
on the number of pixels in the image.

Explain Pixilation –
include diagrams/images

Pixilation is when you
display a bitmap at such a large size that individual pixels, small
single-coloured square display elements that comprise the bitmap, are
visible. The image above is an example of an original image and an image
scaled up. The best and most
used solution is a technique called pixel interpolation that
smoothly blends the colour of one pixel into the colour of the next
adjacent pixel at high levels of zoom. This creates a more organic, but also
much blurrier image. Pixilation is a problem that occurs within all bitmaps.
Alternatives such as vector graphics or purely geometric polygon models can
scale to any level of detail.

What are they typically
used for?

Bitmaps are typically used
to create realistic graphics and images. They are the most common type of
graphic used and supported by digital systems. Bitmaps graphics can also be
known as Raster graphics and pixel maps.

Can they support
transparency?

Some bitmaps can support
transparency. Complex is partial transparency where the effect is achieved
that a graphic is partially transparent in the same way as coloured glass.  Bitmap file formats that support
transparency include GIF, PNG, BMP, TIFF, and JPEG 2000, through either an
alpha channel or a transparent colour.

How does their file size
compare with vectors, explain why there is a difference?

Bitmap file size is
typically large. This is because the computer stores detail of each pixel;
however, the vector file size is small as the computer stores details of
objects. These do not require much memory. Another difference is that a
vector image uses geometrical formulas to represent images. Whereas, the
other way of representing graphical images is through bit-maps in which the
image is made up of a pattern of dots.

Give some software
examples with prices, commercial and education

An example of free
bitmap software is Microsoft Paint, this software is simple to use. However,
a more sophisticated bitmap software is CorelDRAW. This software costs £29.99
on a 30-day subscription and it costs £199.99 on a 365-day subscription.

Give some bitmap formats
and explain what they are suitable for

JPG is a bitmap format,
this file format is now in use for storing digital images, especially on the
web. It is ideal for images that use more than 256 colours, such as digital
photographs. Another format is GIF, it is ideal for images that have large
blocks of a single colour, and it can support up to a maximum of 256 colours.
Unlike with JPGs, it is possible to alter the background colour of a GIF to
make it transparent. This makes it possible to place it over other images or
on webpages. Like a JPG, a TIFF file can be compressed to reduce the file
size, while still maintaining a high degree of image detail. Alternatively,
it can be saved without compression to retain 100 per cent of the original
image taken – where each pixel is identical to the original image taken. Like
a GIF, you can also save it with a transparent background. BMP is an
appropriate file format for Windows users. It is used for general storage
purposes – such as when images are awaiting editing – or as wallpaper for a
Windows desktop. BMPs aren’t suitable for Macintosh computers or the web. BMP
images are large files that require a lot of storage space because no effort
is made to reduce the file size.

Any other details

 

 

                                                            

 

Different
types of graphic images

Vector format

Describe Vector
Graphics by answering the following questions.

What are they made from?

Vector graphics are not
made up of a grid of pixels like JPEGs, GIFs, and BMP images. Instead, vector
graphics are made from paths, which are defined by a start and end, along
with other points, curves, and angles along the way. A path can be a square,
line, triangle, or a curvy shape. Paths can be used to create complex
diagrams or simple drawings.

How well do they scale?

The file size of a vector
graphic is often very small. Vector graphics are scalable, this is because when
you resize them, they do not lose quality.

Include diagrams/images
to show the way a vector scales

 
 
 
 
 
 
 
 
 

What are they typically
used for?

Vector graphic files like
engineering drawings are printed as bitmaps, after vector-to-raster
conversion. However, there main use today is in the context of
two-dimensional graphics.

Can they support
transparency?

Vector graphics may not
strictly be transparent, but it requires the same programming as transparency
in raster formats. On the
other hand, complex vector formats may allow combinations in transparency
between the elements within the graphic.

How does their file size
compare with bitmaps, explain why there is a difference?

The vector file size is
small. This is because the computer stores details of objects, which do not
need much memory. However, bitmaps file sizes are large, due to the computer
storing details of every pixel. There is a difference because a pixel is a
single point or the smallest single element in a display device. If you zoom
in to a raster image you may start to see a lot of little tiny squares. On
the other hand, vector images are based upon mathematical calculations from
one point to another. If you zoom into a vector graphic, it will not
pixelate.

Give some software
examples with prices, commercial and education

Adobe Illustrator
Adobe FreeHand
CorelDRAW
Pro/DESKTOP.

 

Give some vector formats
and explain what they are suitable for

EPS: Adobe’s EPS format is one of the most common
vector image formats. It is the standard interchange format in the print
industry. It is supported widely as an export format. Adobe Illustrator
and recent versions of CorelDraw have good support for writing and
reading EPS.
SVG: The W3C standard vector image format is SVG.
Inkscape and recent versions of Adobe Illustrator and CorelDRAW have
good support for reading and writing SVG.
PDF: Adobe’s PDF format is very widely used as a general-purpose
platform-independent document format. And while it is not exclusively
used as such, it is also a very good vector image format.
AL: The native format of Adobe Illustrator is the AI
format, a modified version of the older EPS format. The AI format is
supported, but is less ubiquitous than the EPS format, and most programs
that read AI can also read EPS.

Any other details

 

 

Different
types of compression

Graphics files sometimes
need to be compressed to make them smaller.

Why do we have to
compress files? You should be able to give a minimum of 3 reasons

Firstly, compression frees up drive space and closes
memory gaps, reducing the time needed to locate data on a drive.
Additionally, compressed files transfer faster and
use less bandwidth than their uncompressed counterparts. Not only does
compression of files save space on the mainframe, it also saves space on
all on and off-site backup.
Furthermore, it reduces the need for new hardware.
This is because IT departments operating mainframes are all too familiar
with the pressures and expectations of doing more with less. In this
case, to store more data without new hardware.

 

Lossy

What is lossy
compression? How does it work?

Lossy compression is the
class of data encoding methods that uses inexact approximations and partial
data to represent the content. These techniques are used to reduce data size
for storage, transmitting content and handling. It works by reducing a file,
this happens by permanently deleting certain information.

Is lossy compression
reversible? Explain

This compression is
fully reversible. This means that when the file is opened, the data is still
there. Therefore, there is no reduction in image quality. The amount of data
reduction possible using lossy compression is much higher than through lossless
techniques.

What type of files would
be compressed using lossy compression? Why?

The class of data
encoding methods that uses inexact approximations and partial data discarding
to represent the content. This
is because uncompressed audio can only reduce file size by lowering bit rate
or depth, whereas compressing audio can reduce size while maintaining bit
rate and depth.

Give some examples of
file formats that use lossy compression

JPEG: a digital image
format which uses lossy compression. lossless A form of compression that
encodes digital files without losing detail. Files can also be restored to
their uncompressed quality.

Find a diagram that
shows how progressive compression can affect an image

 

 

 

 

Lossless

What is lossless
compression? How does it work?

Lossless compression is
a class of data compression algorithms that allows the original data to be
perfectly reconstructed from the compressed data. Lossless data compression
is used in many applications. This is used in the ZIP file format and in the
GNU tool gzip. A lossless compression program can’t do much with this type of
file.

Is lossless compression
reversible? Explain.

Lossless compression
schemes are reversible so that the original data can be reconstructed, while
lossy schemes accept some loss of data to achieve higher compression.

What type of files would
be compressed using lossless compression? Why?

Lossless compression
algorithms reduce file size while preserving a perfect copy of the original
uncompressed image. Lossless compression generally, but not always, results
in larger files than lossy compression. Lossless compression should be used
to avoid accumulating stages of re-compression when editing images.

Give some examples of
file formats that use lossless compression

General examples are
executable programs, text documents, and source code. Some image file
formats, like PNG or GIF, use only lossless compression, while others like
TIFF and MNG may use either lossless or lossy methods.

Find a diagram that
shows how lossless compression works.

 

 

File Types, features and limitations

 

Format

Typical
Use

Features

Limitations

JPEG

Photographs

relatively
small file sizes
16.7
million different colours
supported
by a wide range of software programs

does
not support transparency
does
not preserve layers
lossy
compression

BMP

Store bitmap digital images

Does not degrade when
saved multiple times like JPEG does
Supported by virtually
every device
Bitmap files may translate
well to dot-format output devices such as CRTs and printers.

Uncompressed date
(creating huge files!)
Lacks all the other features of the other
formats
They typically do not scale very well.

GIF

Commonly used for images on the web and sprites
in software programs

Animation
Transparency
LZW compression

They have a maximum colour
depth of 256 bit
They can slow a webpage
down
The often have a blocky appearance

PDF

 Capture
all the elements of a printed document as an electronic image that you can
view, navigate, print, or forward to someone else.

Fast and simple to create
Security
Capability to compress
large files

Website Compatibility
Difficult to Read
Limited OS Support

PNG

Lossless image compression

Minimum compression loss.
The image quality is not changed by any compression ratio
PNG supports many colours
small size files

doesn’t support animation
ill-suited for working
with full-colour images
cannot store multiple
images in one file

TIF

Scanned images

Compatibility
Can also use lossy
compression such as JPG algorithms to reduce file size
Can be compressed to
reduce file sizes using mathematical algorithms such as ZIP or TAR
without loss of image data

Slow speeds when
transferring to online galleries that do support TIFF files
Large file sizes, around
20mb for a 10-megapixel image, so larger storages devices needed for
long term archival use.
Most website and online
images galleries do not support tiff uploading.

SVG

Two-dimensional graphics

small size. SVG image
elements take up much less space than their twins created in raster
format
scalability without
changing the image quality. It is widely used for devices with screens
Retina and those close to them
It’s possible to view the
contents of the SVG file in any browser

the file size is growing
very fast, if the object consists of many small elements
it’s impossible to read a
part of the graphic object, only the entire object and it slows you down

PSD

Adobe Photoshop

Utilize all Photoshops
features
Open saved file with
layers
Tight integration between
Adobe products, you can directly import a Photoshop file into
Illustrator, InDesign, etc.

Large file size
PSD is proprietary to
Adobe. So, it is not widely supported by other apps like TIFF is.

AI

Logos and print media

Colour Theme panel. Create,
explore, save, and retrieve colour themes across applications.
Can be scaled without loss
of quality.
Crop bitmap images
directly within Illustrator to discard excess parts.

Requires specific software
to be opened.
Only two-dimensional image
extension.
Although the files are
relatively small, they can sometimes be difficult to share.