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Pixel
Pixels are the building blocks of all images in digital form, all screens display in pixels. For example the image above is made out of few pixels so we can see the square pixels. A resolution such as 1920 by 1080p is made up of 1920 pixels width by 1080 pixels high meaning a total of 2,073,600 pixels on a screen. The name pixel comes from picture element. Colour depth is the number of colours available to a pixel, 1 bit colour depth is comprised of 2 colours where as true colour (24 Bit) is comprised of 16,777,216.
Pixels are the building blocks of all images in digital form, all screens display in pixels. For example the image above is made out of few pixels so we can see the square pixels. A resolution such as 1920 by 1080p is made up of 1920 pixels width by 1080 pixels high meaning a total of 2,073,600 pixels on a screen. The name pixel comes from picture element. Colour depth is the number of colours available to a pixel, 1 bit colour depth is comprised of 2 colours where as true colour (24 Bit) is comprised of 16,777,216.
· Colour Models – RGB and CMYK
RGB colour is made up of red, green and blue and is the colour model used on screens. The red, green and blue light needs to be added to create a white, thus why it is additive. CMYK colour is made up of cyan, magenta, yellow and black and is the colour model used for printing images. The colours need to be taken away from the image to create white which is why it is subtractive.
· Resolution
Resolution is the quality of an image, as resolution goes up the quality increases. Resolution measures the amount of pixels an image can be on a screen. For example the image above shows a videogame being displayed in a 1920 by 1080 pixel resolution. However there are more factors which can affect the way an image looks, the distance away from the screen affects the way we see the image because if we are to close the image can look slightly pixelated and can ruin the look of it.
Raster Images: file formats and uses - psd, bmp, gif, tiff, jpg, png
A raster image is a image composed of pixels, it can be scaled down but not up as when it is scaled up it becomes pixelated. Raster images are usually used for picture editing and saving photos. Files formats used for raster images include PSD, BMP, GIF, TIFF, JPG and PNG.
PSD-Photoshop document
BMP-Bitmap
GIF-Graphics interchange format
TIFF-Tagged image file format
JEPG-Joint photographics expert group
PNG-Portable network graphics
· Vector Images: file formats and uses - eps, wmf, fla, svg, ai
Vector images are made using mathematical equations which tell the program what to do. Vector images can be created in adobe illustrator. Vector images can be scaled up or down and will not get pixelated. Format files or vector images include EPS, WMD, FLA, SVG and AI. AI is the adobe illustrator default file format. Vector images are usually used in banners or logos because when they are scaled up they don't become pixelated.
EPS-Encapsulated post script
WMD-Windows media download file
FLA-flash application file
SVG-Scaleable vector graphics
AI-Adobe illustrator file
· Cross-platform Images: format and uses - pdf
A PDF file is a portable document format file. When a file such as a document , image or website is converted to a PDF they look just like they would if printed, but unlike printed documents they can contain clickable links, buttons, video, audio and images. They can be read using Adobe acrobat.
· Compression - lossy and lossless
Lossy compression is when a image is compressed to a smaller file size but it loses some data. This makes the image become blocky (pixelated) and loses quality however the amount of pixels in the image does not change but the pixels copy data from nearby pixels which makes i look blocky.
Lossless compression is when an image is compressed partially but not as much as lossless compression. Also lossless compression doesn't lose any data therefore it retains it quality and does not become blocky unlike lossy compression.
· Image Capture Devices – scanner, digital camera, tablet/smartphone
All capture devices use a lens which gathers and focuses light. The local point is the point in which the image flips around because the light rays continue going in the same direction they are. In digital cameras, tablets and smartphones the sensor which contains photosites converts the light into an image, each photosite represents one pixel in the final image so when the image is taken it has the same amount of pixels as the sensor. e.g. a 4 megapixel camera would have around 4 million pixels in the final image.
A chemical camera uses RGB colour dyes to take an image but is basically the same concept as a digital camera. In a scanner the sensor scans the image by lines of pixels to take an image instead of taking all the pixels at once like a digital camera.
· Optimising
Optimising is where you change settings, file format, colour models and other things to get the best possible image from the software you are working from. For example if you are playing a game you could optimise that game to get the best possible experience out of it by changing settings. Also if you are going to print an image you have saved as a PSD you will optimise it by changing the colour model to CMYK and by changing the file format to PDF which is a cross platform file format.
· Storage and Asset Management
Storage management is where you save all of your files to make it better to access and more convenient for you. For example if you have to take in work to college you may save it on a usb, skydrive or send it to yourself over email.
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