Digital Image basics

Digitalization of an image

• Pixel stands for "picture element
• Pixels are the basic unit of digital images
• An image comprises a grid of tiny colored squares (pixels)
• Resolution determines the number of pixels in an image or on a screen
• Higher resolution means there are more pixels, hence more detail
• Color depth defines the number of bits used to represent the color of each pixel
• More bits allow for a broader range of colors

Capturing an Image

• Light enters the image sensor
• Microlenses concentrate incoming light onto photodetectors
• RGB color filters separate light into red, green, and blue components
• Photodiodes convert light into an electrical charge
• This electrical charge is amplified and converted into a digital signal
• The signal is then processed to create a complete image

Image Sensors

• CCD (Charge-Coupled Device) transfers charge pixel by pixel to convert it into an electrical signal
• CMOS (Complementary Metal-Oxide-Semiconductor) sensors process signals directly at each pixel
• CCD sensors offer high image quality, especially in low light, but are more expensive and consume more energy
• CMOS sensors are energy-efficient and are standards in most cameras and smartphones

Standard Resolutions

• 640x480 pixels is known as VGA
• 800x600 pixels is named SVGA
• 1024x768 pixels is referred to as XGA
• 1280x1024 pixels is SXGA, which was used before wide screen
• 1366x768 pixels is known as HD
• 1600x900 pixels is called HD+
• 1920x1080 pixels is called Full HD or 1080p
• 2560x1440 pixels is known as QHD or WQHD, it is used for high end gaming
• 3840x2160 pixels is known as 4K, UHD or 2160p, a standard for TVs and displays
• 7680x4320 pixels is known as 8K, this is one of the highest resolutions available

Color Depth

• 1-bit color depth represents 2 colors, black and white
• 4-bit color depth represents 16 colors.
• 8 bit color depth represents 256 colors.
• 15 Bit color depth represents 32,768 colors.
• 16 bit color depth represents 65,536 colors.
• 24 bit color depth (Truecolor) represents over 16.7 million colors.
• 32 bit color depth represents over 16.7 million colors.

RGB Model

• The RGB (Red, Green, Blue) model is a color model used in electronic systems to display and capture images
• Every color is made from the combination of the three colors
• Color are created from adding each different color to create a mixing palette

CMYK Model

• The CMYK (Cyan, Magenta, Yellow, Key/Black) model, which is used in the industry for reproducing colored images and graphics
• The CMYK model is a combination of four colors
• Tints and shades can create various different colors and can produce different images
• The black color is added depth and detail

RGB Color Creation

• Color intensity in digital graphics is often expressed on a scale from 0 to 255
• A value of 0 means no color is added and 255 indicates full intensity
• Clean red is indicated as (255,0,0)
• Combinations of colors create new colors
• Yellow is made from a combination of full intensity of red and green (255,255,0)
• Aqua/Azúrová is created from combining a full intensity of green and blue (0,255,255)
• Fuchsia/Purpurová is created from combining a full intensity of red and blue (255,0,255)

Raster vs Vector Graphics

• Raster graphics form images using a grid comprised of pixels
• Vector graphics renders mathematically with object points Raster Graphics have:
• Fixed resolution.
• Common formats comprise JPEG, PNG, BMP, GIF
• Images with complicated colors, patterns, and photos are suitable. Vector Graphics:
• Can be scaled without lost resolution
• Commong formats comprise SVG, AI and EPS
• Suitable for creating logos.
• Vector images are great for simpler shapes while raster is suitable for images with different objects and gradients.

Use of Raster Graphics

• Raster images are commonly used where detail and complexions are vital
• Used when capturing images with detail by the details and colors of Raster form which is vital

Use of Vector Graphics

• Vector images are useful for when you need the perfect shapes to be scaled

Compressing Images

• Compressing images reduces the amount of data that helps preserve the images
• Can either by done Lossy and Loss Free
• Loss Free creates nearly identical Images because they can be preserved

Raster Graphic Formats

• PNG (Portable Network Graphics) supports color depths from PNG-8 to PNG-48 (including the alpha channel) and provides full transparency
• TIFF (Tagged Image File Format) may contain non-destructive compression such as LZW or ZIP
• BMP (bitmap) can have non-destructive compression in some versions, although it is more often without compression
• GIF (Graphics Interchange Format) uses LZW compression, which is non-destructive but limited to 256 colors
• WebP - Google developed a format that provides both lossless and lossy compression

HSV (Hue Saturation Value) Color Model

• Hue determines color type
• Saturation represents the purity of the color, that is how much of the colors of the shade are "clean"
• Jas determines how the light or dark the color is

Basic sound terms

• Analog signal: This signal is continuous in time and can have any value within a certain range
• Digitization (analog to digital conversion): Process of converting an analog signal to digital
• Sampling Rate: Number of samples of the audio signal recorded per second, expressed in hertz (Hz)
• Bit Depth: Number of bits used to store each sample
• Quantization: Rounding the value of each sample to the nearest value that can be expressed with the bit depth used
• PCM (Pulse Code Modulation): A method used to digitize analog signals
• Audio compression: The process of reducing the size of an audio file
• MIDI (Musical Instrument Digital Interface): Technological standard that allows electronic musical instruments, computers and other devices to communicate and synchronize

Frequency and Audible Spectrum

• The higher the frequency in a wave is, the more quick it occurs
• Frequency is measure in unit Hertz (Hz) and the time it takes to perform a complete cycle
• The human hearing in a good hearing ranges from 20 Hz to 20 kHz (20,000 Hz)
• Infrasound are waves that are less than 20Hz and can be normally heard and can some times be a vibration.
• Ultrasound are waves that are above the normal hearing of 20 kHz used for technological purposes.
• Sound requires waves to travel through the correct medium and through various different methods

Frequencies and tonal ranges of music and voice

• The instrument can range from low or high depending on the sounds, the higher sounds include the higher frequencies
• These frequencies are need to digitize and create music

Sound Digitization Process

• Analog signal, the original wave form is converted into digital wave.
• Sampling (measuring the amplitude) that creates a series of points
• Quantization, of which points are converted to nearest points
• Encoding by which these waves forms are converted into binary.
• Compression decreases sizes on the data of files.

Formats of the digital sounds

• WAV- lossless
• MP3- Lossy
• AAC- Lossy
• FLAC- Lossfree
• ALAC- Lossfree
• AIFF-Lossfree Ogg is similar to the lossy and Loss free options

MIDI

• MIDI- Musical instrument Digital Interface is an interface between computers and instruments such as keyboards
• Sends musical instruments to a DAW
• MIDI contains information on different components such as pitch, intensity and controllers not the sound of waves.

Video Digitization

• Digital graphics are often a fast display of static images (frames)
• Every image frame is displayed for a amount of frames
• Every Frame is used for the processing and used for model
• Has both sound and music that play at the same time
• This combination with sound and images helps to create video.

Compression in Video

• Compression reduces the amount of data that must be retained which creates for faster download
• Can be either Lossy or Loss free data loss
• Lossy compression is the "unneeded" portions that are discarded to create for less data.
• The codes are coded and decoded form the video and allow for the viewing to take place.

Explore the fundamentals of digital images, from pixels and resolution to color depth. Understand the process of capturing images using sensors composed of microlenses, RGB filters and photodiodes. Learn about CCD and CMOS image sensors.