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 Bitmap images
Pixels of colors Great tonal variety Take up a lot of space Lose quality with zoom Photographic use
Vectorial images
Segments and polygons Coded by formulas Don’t occupy much space Don’t lose quality with zoom Publicity use (logotypes, etc)
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 bit= 21= black and white 2 bits= 22= 4 colors 8 bits= 28= 256 colors 24 bits= 224= 16 million colors 1
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 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
To do this exercise we will use: http://pixlr.com/editor/
Exercise 2. Change the resolution 1.
Open the same photo in pixlr 2. Click Filtro > Pixelizar 3. Save the file. Archivo > Guardar
To do this exercise we will use: http://pixlr.com/editor/
Exercise 3. Change the tone 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
To do this exercise we will use: http://pixlr.com/editor/
Exercise 4. Change the saturation 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
To do this exercise we will use: http://pixlr.com/editor/
Exercise 5. Change the luminosity 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
To do this exercise we will use: http://pixlr.com/editor/
Exercise 6. Change the contrast 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
To do this exercise we will use: http://pixlr.com/editor/
Exercise 7. Use other filters and adjustments 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.
To do this exercise we will use: http://pixlr.com/editor/
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.