Digital images are made up of pixels which are tiny squares that each have a color value. Higher resolution images have more pixels and appear clearer when zoomed in. File formats like JPG and PNG compress images to reduce file size. Raster images use pixels while vector images use math to scale smoothly. Digital cameras capture high resolution images and store them digitally rather than on film. Images need optimization for intended use like web, print, or screen display based on factors like size, quality, and compression.

1. Digital Graphics Pixel Image Resolution
Image resolution is the size of the image
Technology A pixel is a tiny element which makes a pic-
and how many pixels are used the make
the picture up. If a picture is high resolu-
Omar Wahid ture. There are millions in each image and
can only be seen when the photo is zoomed
tion then it will contain more pixels and
will remain clear and not pixelate when
Unit 19 into. Each pixel is a small square and they zoomed into. The only downside of having
are the basic building blocks into making
Teacher: an image.
a high resolution image is that the size of
the file may be quite large. Lower resolu-
Carol Pearson High resolution images have more pixels
which makes them look like a high qual-
tion files have less pixels and are prone
to pixilation however they are quite small
ity picture. Lower resolution pictures have in size. If an image is 2048×1536 then it
As the old cameras evolved into digital noticeably less pictures. The best way to
cameras the technology of photos have equals 3,145,728 pixels or 3.1 mega pix-
tell is by looking at the edge of the shapes els. This is worked out my multiplying the
also evolved. Photos used to be developed when zoomed into for example circles are
by using the negatives from the camera height and width of the image.
made up of tiny square shaped pixels, if its
reel. Now photos are saved onto a memory low quality the pixels will be visible and
card on the camera and can be transferred will pixelate.
straight onto a computer. These photos can
then be edited using a variety of photo edit-
ing software.
Photos can be edited to enhance the look
The first image shows a low resolution im-
of them for example a model can be air
age this is obvious by the pixilation.
brushed using photo shop to give the ap-
Low resolutions images are popular for
pearance of having flawless skin.
web sites because they take less time to
This picture shows that even the circu- download and display on the screen as the
I will cover the technology of digital graph-
lar part of the photo is made up by small bandwidth isn’t being consumed by large
ics and how they are constructed and some
squares to construct the image. size pictures.
of the benefits and drawbacks.

2. Raster Images File Extensions
Raster images are is also known as .bmp A file extensions is the format of the im-
(bitmap). It uses bits to create pixels by age. The main way to tell the extension are
using a point of colour to create the over- the letters after the file name eg, image.
all image. Each bit or pixel is assigned bmp, this is a bitmap file. Extensions and
with its own number which translates into file formats are used to identify and organ-
a colour. It used the RGB (Red, Green, ise files.
Blue) colour system and has 256 differ- The first picture is the original and the sec-
ent colours. Each pixel is given a specific ond is compressed to 98%. We can clearly BMP (Bitmap) - Bitmaps are tiny ele-
code which converts into an image. see the quality of the image is lost how- ments which are a different colour to make
ever the file itself is less than 1MB (Mega up a picture.
Compression Byte). The user must be able to find the
Images can be compressed to save space balance between the size of the file and the PNG (Portable Network Graphic)- Is used
on storage media or on a web site. There quality of the image. for lossless images mainly for the internet
are two main types of compression, Lossy and games it supports 8bit transparency.
and Lossless. Lossless compression uses binary code
to compress the file and split the file up GIF (Graphical Interchange Format)- This
Lossy compression is when a file is de- so that when is decompressed it will not can be animated or still. Its a very small
compressed there are bits of the data that lose any of the information. GIF images image used for logos and web sites
are missing. This can be on purpose or (Graphics Interchange Format) use this and can store up to 256 colours. Dif-
because the information is lost. Most of form of compression because they don’t ferent GIF images can be layered to create
the times the viewers will not be able to lose any of the image quality. an animated image.
tell the difference because only ir-
relevant information is missing. The more TIFF (Tagged Image File Format)- Tiff
the file is compressed the greater the loss images are used for magazines and dig-
of graphics will be. The data is lost on ital photos they are usually lossless but
purpose so the user can save some space. can be lossy and be compressed by a small
Its common within image and sound files. amount only. They support a large amount
JPEG images are commonly compressed Both of these images are identical how- of colour and detail.
to use on the internet. ever the second one is compressed.

3. JPG (Joint Photographic Experts Group)-
Is a common file format. Its used for logos
Vector Images File Extensions
Vector graphics are made by using points
and for digital photos. The files can be lines and curves. They use geometry and EPS (Encapsulated PostScript) - Can be
compressed however it is noticeably dif- maths to develop shapes and colours. They used to mix pixels with vector images. It
ferent due to it being lossy. are smaller then raster images and don’t can be used over many operating sys-
pixelate when enlarged. They are used for tems as its very versatile.
PSD (Adobe Photoshop Docu- businesses for small images such as busi-
ment)- This is the default format of the ness cards and large logos. AI (Adobe Illustrator file) - The default
Adobe software. Its supports RGB, format for Adobe illustrator. Its used be-
CMYK, grayscale, monochrome, tween Photoshop and illustrator. They are
duotone,indexed colour, Lab colour, and used to make vector images and edit them.
multichannel colour modes. Its then saved
as the desired output format when com- FLA (Adobe Flash Animation) - The for-
pleted. mat in which flash animations projects
are saved in. They are used in Adobe and
are later compressed and turned into SWF
files to be uploaded to the internet.
This image shows that the vector image
doesn’t lose any of the quality or pixelate
even when magnified 7 times.

4. Bit Depth Monochrome True Colour
Each bit in an image is given a specific Is where only a single hue is used to make This allowed you store store massive
number. The combinations of these num- an image. All the other colours are turned amounts of colour and shade such as 24
bers form the colours that we see in the off and black and white and grey are used. bit images. It doesnt restrict the amount of
images. The “bits per pixel” (bpp) refers colours used however can be very large in
to the sum of the bits in all three color size.
channels and represents the total colors
available at each pixel. If an image is a
24-bit image, then that image uses 24 bits
of information to describe each pixel, (24
bits per pixel).The larger the bits per pixel,
the more colors available in the palette.
A 1-bit image has only two colors in the
palette: black and white.A 24 bit image
potentially has 16,777,216 colors in its
palette.
High Colour
High colour uses two bytes of information
to store the intensity values for the three
colours, using 5 bits for blue, 5 bits for red
and 6 bits for green. The resulting 32 dif-
ferent intensities for blue and red and 64
different intensities for green results in a
very slight loss of visible image quality.

5. Colour Space YUV Each hue is assigned a number between
0 ° and 360 °.
Colour space is how colours are shown The Y component determines the bright-
numerically. Its typically used for scan- ness of the color referred to as luminance
ners and used RGB and CMYK. Colours or luma, while the U and V components
that have no mapping are not universally determine the color itself the chroma. It
recognised. As the user goes further away takes the human eye into acccount and can
from the centre of the colour space the compress any errors. Its a colour encod-
colour saturates. ing system used for PAL and NTSC TVs
worldwide. Luminance is the brightness
of an image and the chroma is the colour
when these two are paired they form the
video image.
Greyscale
Greyscale is not to be confused with black
and white. It uses different shades of grey
to form the image. The colour intensity HSV
is the same from red green and blue. It Hue saturation value. This was first de-
ranges from 0 to 1. veloped for gamers and is used widely for
colour pickers in image editing software.
The hue is the colour pigment and the sat-
uration value is how rich the colour is and
how bright it is.

6. Image Capture Digital Camera
There are various different ways to cap- Digitals cameras store images and video
ture an image. The most popular is by us- onto the onboard memory or memory
ing a digital camera. A digital image usescard. It had evolved from the old cameras
a camera to capture an image and store that used a film. The image is enhanced
it into a memory card, depending on the due to the better lens and technology such
camera the image will be high resolu- as image stabilisation. The image resolu-
tion. Most cameras are over 5 megapixels tion is the amount of pixels in the image
which means there are over 5 million pix- and the size of the image. Most cameras
have a large resolution ranging from
els so the image will be clearer and can be
manipulated better. The saved image will 640x480 to 3264x2448, the resolution
be saved to a specific format such as JPG depends on the megapixels the camera can
depending on the camera and can be trans- capture. The larger the resolution the big-
ger the file size will be. When taking a pic- Most cameras come with a memory card
fered to a computer and manipulated or
ture factors such as white balance and red however if large images and videos are re-
shared over the internet or emailed.
eye reduction are automatically corrected corded the memory can be used up quick-
so the image isnt impaired. When taking ly. The photographer must set the camera
Another form of capturing an image is a
to take less resoulution pictures but still
scanner which taken an existing photo and a photo the focus and exposure must be
taken into consideration. Most cameras keep some of the quality to find the bal-
scans it into a computer and can then be
have an auto focus so the foreground is ance.
manipulated.
more clear and the background is blured.
The exposure is the amount of light on Scanners
the image taken. Most cameras restrict the Image scanners are used to scan written
amount of light so its not over exposed for documents or images onto a computer.
example in the day time. These features There are many types of printers but the
can also be added in photo editing soft- two main types are flatbed and drum. The
ware. When a picture is taken the quality work like a photocopier but there is no
can be seen by the pixels per inch PPI. printed copy its a digital copy.
This is measuring how many pixels there Flatbed scanners have a glass pane and a
are in each square inch this is also known bright xenon light. The sensors have RGB
as pixel density. scanners to determain the colour in the im-
age

7. Drum scanners are used for detailed im- Images that are for screen should have a
ages. They mount the image on a PMT large resolution and as many PPIs as pos-
Tube and is then put on a glass cynlinder sible. Rich colours will ensure the image
were each beam is passed through a colour looks its best. If the monitor is HD then
sensor. the picture will look even more enhanced.
Lossless images are the best because they
wont be compressed and wont lose any of
its quality.
For image printing the size of the image
depends on the size of the intended image.
If the size of the paper is A3 then a high
resolution image will be needed using a
laser printer. Ink printers dont give a con-
sistent print.
Images must be optimised for the intended
purpose. If its for a website its best that
the image is a GIF or JPG so that it can
be compressed and doesnt take too much
bandwith when being downloaded. Its
very important to get the right balance be-
tween image size and image quality.
The bit depth, dimension and resolution
are where there are unecessary bytes. If
necessary the image should be cropped
and the height and width changed.
Lossy images are the best because the im-
ages can be compressed.