The resolution of an image is determined by the number of points which make up the image. This could be either the number of pixels that make up an image on screen or the number of dots that make up an image which is printed. An image will be more detailed and sharper if more dots are used to create the image. If a bitmap is used, information needs to be stored for the image regardless of its size. However, this does not apply to vectors, as the resolution only needs to be made when the image is printed.
Users, such as blog creators, must take resolution into consideration whenever they are uploading an image onto their blog. The higher the resolution, the bigger the image's file size will be. If the image has a large file size due to it having a high resolution, it will take longer for the image to load up onto the blog. If someone who wants to view the blog has to wait a long time, they will most likely not bother waiting for the image to load up. Therefore, the blogger must must ensure that he or she chooses images which have an appropriate resolution in order to make their blog more viewer friendly.
Colour Depth
The colour depth of an image is the number of colours which are used in that image. The more colours used, the more realistic the image will be. With bitmap images, the colour depth which is chose, will affect the final size of the image. Monochrome, Greyscale, Palleted, 16 Bit Colour, 24 Bit Colour and 32 Bit Colour are all examples of colour models.
Monochrome (black and white) has the lowest storage requirement as we only need to know if the pixel should be on or off.
Greyscale: As a byte can be 1 of 256 values, each pixel needs 1 byte of storage space.
Palleted (256 Colours) allows each pixel to be 1 of 256 colours stored in the formats table, known as a palette. As the palette is saved along with the file, the file size will be increased. As with Greyscale, each pixels is allocated 1 byte of storage space.
16 Bit Colour (High Colour): Each pixel requires 2 bytes of storage space to store information. 1 byte is allocated for colour and the other byte is allocated for the shade of that colour.
24 Bit Colour stores the Red, Green and Blue value for each pixel. Each pixel can have 1 of 256 colours. As up to 16 million colours can be used for a single image, the image is usually very realistic. However due to the large amount of colours which can be used, each pixel needs 3 bytes of storage space.
32 Bit Colour (True Colour) uses the same format as 24 Bit Colour. However, it is different as it stores the transparency information for each pixel. Each pixel can then be 1 of 256 values, from opaque to transparent. Due to information on transparency being stored, each pixel needs 4 bytes of storage space.
No comments:
Post a Comment