THE DIGITAL IMAGE

3rd ESO Visual Arts, Teacher Simone

The digital image

What is a “digital image?”

The digital image

A digital image is an image that is created, stored

or manipulated through a computer or another

digital support. It is seen on a screen or monitor.

Digital images

In our time, digital images are a large part of the

images we see on a daily basis– on a computer

screen, in the cinema, in television, in video games,

etc.

What do we know about Digital

Images?

Megapixels?

Pixels per inch?

Resolution?

Depth of color?

Bitmap images

Bitmap images

Are digital

photographs.

They’re

formed by

small squares

call pixels,

similar to a

“mosaic”

Bitmap images

The images

contain a

wide variety

of colors and

tones.

Bitmap images

These images

lose quality as

we “zoom”

Bitmap images

In a bitmap image,

each pixel is

formed by three

components: Red,

Green and Blue

(RGB).

Each pixel is coded

separately by the

quantity of each

color found in the

pixel.

Bitmap images

When printing

a bitmap, the

colors

components

are Cyan,

Magenta,

Yellow and

Black (CMYK).

That is why, in

your printer,

there are 3

color

cartidges and

1 black.

Vectorial images

Vectorial images

Are formed by segments and polygons of color.

They are coded by formulas.

That is why they take up little space on a digital support.

Vectorial images

They do not

lose quality

when we

zoom.

Bitmap images vs. Vectorial images

Bitmap images vs. Vectorial images

Bitmap images vs. Vectorial images

Bitmap images vs. Vectorial images

Bitmap images vs. Vectorial images

Pixels of colors

Great tonal variety

Take up a lot of space

Lose quality with zoom

Photographic use

Segments and polygons

Coded by formulas

Don’t occupy much space

Don’t lose quality with zoom

Publicity use (logotypes, etc)

Bitmap images Vectorial images

Bitmap images vs. Vectorial images

Bitmap images vs. Vectorial images

Bitmap images vs. Vectorial images

Let’s get to work

Look at the vectorial image.

Transform the image into pixels, just like a bitmap.

Remember that each pixel must be a complete

square, not part of a square

Use pencil colors, and color mixing, to replicate the

image

Here is your vectorial image…

Let’s review!

What is a digital image?

What is a bitmap image?

What are some differences between bitmap and

vectorial images?

What is a pixel?

Quality of digital images

Resolution

Detail or quality of an image

Amount of PIXELS PER INCH (ppi)

Key values:

Computer screen: 72 ppi.

Printer: 600-1200 ppi.

Digital cameras: 1 MP = 1.000.000 ppi.

Resolution

Bits

The number of distinct colors that can be

represented by a pixel depends on the number of

bits per pixel (bpp).

A «bit» is short for BINARY DIGIT.

Bits

What is binary code?

A language used in computer programming.

Every bit can represent two values. In binary code,

this is the 0 and the 1.

Color Depth

More bits=more colors

1 bit= 21= black and

white

2 bits= 22= 4 colors

8 bits= 28= 256 colors

24 bits= 224= 16

million colors

Color modes

Monochromatic

1 bit: 2 colors 8 bits: 256 col

Greyscale RGB

8 bits: 256 16 bits: …

Guess the number of bits

1 bit

2 bit

4 bit

24 bits

Image formats

BMP (Bitmap)

High quality

Large files

GIF

Low quality (maximum 256 colors).

Small files

JPG

High quality (16 million colors)

Formato comprimido: pierde calidad

TIF

High quality

Large files

PNG

Low quality (maximum 256 colors).

Usually internet images

Take a portrait picture

It can be of yourself or a friend

You can use photobooth or the camera

You musn’t use ANY color effects in photobooth

The photo must be in color and have good illumination

Exercise 1. Change the color mode

To do this exercise we will use: http://pixlr.com/editor/

1. Select a photograph

2. Open the photo in pixlr

3. Change the photo to

greyscale. Click > Ajustes

> búsqueda de color

4. Save the file. Archivo >

guardar

Exercise 2. Change the resolution

To do this exercise we will use: http://pixlr.com/editor/

1. Open the same photo in

pixlr

2. Click Filtro > Pixelizar

3. Save the file. Archivo >

Guardar

Exercise 3. Change the tone

To do this exercise we will use: http://pixlr.com/editor/

Tone is the amount of a

certain color in a photo.

1. Open the same photo in

pixlr

2. Change the tone. Click

Ajustes > Tono y

Saturación…

3. Save the file. Archivo >

Guardar

Exercise 4. Change the saturation

To do this exercise we will use: http://pixlr.com/editor/

Saturation is the intensity

of the colors in the photo

1. Open the same photo in

pixlr

2. Change the saturation.

Click Ajustes > Tono y

Saturación…

3. Save the file. Archivo >

Guardar

Exercise 5. Change the luminosity

To do this exercise we will use: http://pixlr.com/editor/

Luminosity is the brightness

of the photo

1. Open the same photo in

pixlr

2. Change the luminosity.

Click Ajustes > Brillo y

Contraste…

3. Save the file. Archivo >

Guardar

Exercise 6. Change the contrast

To do this exercise we will use: http://pixlr.com/editor/

Contrast is the amount of

difference between the

lights and darks of a

photo

1. Open the same photo in

pixlr

2. Change the contrast.

Click Ajustes > Brillo y

Contraste…

3. Save the file. Archivo >

Guardar

Exercise 7. Use other filters and

adjustments To do this exercise we will use: http://pixlr.com/editor/ Filters are used to create

other effects in a photo

1. Open the same photo in

pixlr

2. Change adjustments and

filters. Click Filtros or

Adjustes

3. Save the file.

Exercise 8. Combine the 12 images

Combine all of the images

in one image

1. Open all the photos in

pixlr

2. Click Imagen > Tamaño

de lienzo…

3. Change the size of the

canvas to fit 4 x 3 photos

4. Save the file.