Please enable JavaScript.
Coggle requires JavaScript to display documents.
UNIT 12
IMAGES :frame_with_picture: (resize (To change the physical…
-
Images are either vectors or bitmaps. Bitmap images are made out of small parts called pixels. Vector images are made using coordinates and geometry. Images can be compressed to reduce file size.
Bitmaps:
Bitmap images are widely used on digital cameras, smartphones and online. Common bitmap image file types include JPEG, GIF and PNG. Bitmaps are also known as pixelmaps or raster graphics.
Vectors:
A vector image uses scalable shapes such as straight lines and curves, using coordinates and geometry to precisely define the parts of the image. It is more efficient than bitmaps at storing large areas of the same colour because it does not need to store every pixel as a bitmap does.
Image files usually also contain metadata. Metadata means 'data about data' and provides information about the image. The information includes:
- filename
- file format - eg JPEG, GIF or PNG
- dimensions
- resolution
- colour depth time and date the image was last changed
- camera settings when the photo was taken
- GPS
Compression
Compression is used to reduce file sizes and change various attributes of an image file. These attributes include:
- file type
- resolution
- dimensions
- bit depth
Compression can be lossy or lossless. Lossless compression means that as the file size is compressed, the picture quality remains the same - it does not get worseTypes of compressed image files
There are a number of types of compressed image file. These include the following. PNG
PNG is a lossless compression type. It is often used where the graphic might be changed by another person or where the image contains layers of graphics that need to be kept separate from each other. It is high quality. JPEG
JPEG is often used for digital camera images because it has a fairly small file size for the quality that it displays. JPEG is a lossy format that offers a higher compression rate than PNG in the trade-off for quality. GIF
GIF compresses images to a maximum 8-bit colour depth, making it unsuitable for high-quality photographs. GIF is often used where transparency is needed on the graphic. GIF can also be used to store simple animated images.