Digital Graphics

Hello, this week I will be talking about Digital Graphics. 
Pixels

A pixel is short for PICture ELement, because a pixel is the smallest element of the digital image. If you zoom so far into a picture, you will see the pixels.

Normally, you cannot see the individual pixels, because they are so small. This is a good thing; because most people prefer to look at, clear images rather than, "pixelated" ones.

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But if you set your screen to a low resolution, such as 640x480 and look closely at your screen, you will be able to see the individual pixels. These look like little dots.

A pixel usually consists of a ratio between three component colours, red, green, and blue (RGB). A pixel is just numbers representing a RGB data value. RGB can mix together to form any color.

When the highest amount of each color is mixed together, white light is created. When each hue is set to zero amount, the result is black. TVs and computer screens use RGB to create the colorful images you see on the screen.

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Bit rate describes the rate at which bits are transferred from one location to another. In other words, it measures how much data is transmitted in a given amount of time.

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Pixel counts are referred to as resolution, this is to describe the pixel resolution with the set of two positive numbers, where the first number is the number of pixel width and the second is the number of pixel height, for example as 640 by 480. Pixel Resolution describes either how many pixels a monitor can display. The higher the resolution, the more can be displayed on the screen.

Raster Images

Pictures you have either imported from a digital camera or have found on the Internet are called raster graphics. They are made up of grid of pixels, usually referred to as a bitmap. The larger the image, the more disk space the image file will take up.

The following are some file extensions:
.bmp – (bitmap image file) No compression, can use different bit rates up to 32 bit. BMP files may contain different levels of color per pixel, depending on the number of bits per pixel detailed in the file header. They may also be collected using a gray scale color scheme.

.jpg – (JPEG image) Lossy compression, 8 bit per colour (24 bit total). JPEG format is best for compressing photographic images. So if you see a large, colorful image on the Internet, it is most likely a JPEG file. Although JPEG images can contain high-resolution, colourful, image data, it is a lossy format. This means some quality is lost when the image is compressed. If the image is compressed too much, the graphics become unusual (blocky) and some of the detail is lost.

.png – (Portable Network Graphic) Lossless compression, 24 bit. PNG contains a bitmap of indexed colors and uses lossless compression, similar to a .GIF file that is usually used to store graphics for Web images. PNG images include an 8-bit transparency passage, which allows the image colors to fade from opaque to transparent. PNG images do not require CMYK color support because they are not planned for use with professional graphics.
.gif -   (Graphics Interchange Format) Lossless compression, 256 colour. Gifs are based on indexed colors, which is a palette of at most 256 colors. This helps greatly reduce their file size. These compressed image files can be quickly transmitted over a network or the Internet, which is why you often see them on the Internet.

.tiff - (Tagged Image File Format) Either compression, 16 bit per colour (48 bit total) TIFF is the standard image format across multiple computer platforms.

Vector Images

Vector images are made up of many individual, accessible objects. Objects may consist of lines, curves, and shapes with editable aspects such as color, fill, and outline. Since vector graphics store image data as paths, they can be enlarged without losing quality, which makes them a good choice for logos and other types of drawings.

Vector images are usually made up of solid areas of color or gradients, but they cannot describe the endless delicate tones of a photograph. That's why most of the vector images you see tend to have a cartoon-like appearance.

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 ß Vector Image

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ß Raster Image

You can increase and decrease the size of vector images to any degree and your lines will remain clear and sharp, on screen and also on print. 

Vector images have many advantages, but the primary disadvantage is that they're unacceptable for producing photo-realistic imagery.

Bit Depth

To control the color of each pixel on the screen, the computers managing system must commit a small amount of memory to each pixel. If more bits of memory are dedicated to each pixel in the display, more colors can be managed. For example: When 8 bits of memory are dedicated to each pixel, each pixel could be one of 256 colors. 256 is the maximum number of unique combinations of zeros and ones you can make with.

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ß Example of Bit Depth

True Color is named because it can display so many colors it provides a true sign of the original subject for the human eye. Higher bit depths such as 36 and 48-bit are now available, providing even more accurate color representation.

Colour Space - Colour space is the amount of colour stored in each image where the sections of the colour model are defined exactly allowing the people looking at it to know the exact look of each colour. Most monitors will work using the RGB colour model, as the black is the absence of light and the colours are different kinds of light displayed on top of each other with white being the outcome if you layer all 3 in equal amounts.

Greyscale – Greyscale images are made up of changing amounts of grey, with black as the weakest and white as the strongest.

 

Image Capture - Images can be captured through things like scanners, digital camera’s etc. However some of there are other items such as data storage can also be ‘branded’ as data storage that can also be ‘branded’ as a form of capture.