The differences between saving images for Print and for the Web
Software packages:(Industry Standard)word processing: Microsoft Word image manipulation: Adobe PhotoShop vector-based images: Adobe Illustrator page layout: Quark XPress |
Image Formats:TIFF = Tagged Image File Format PSD = Adobe PhotoShop Data file (extension) (includes layer info) PICT = Picture JPEG = (Joint Photographic Expert Group) a compressed format for photographs EPS = Encapsulated PostScript format, used for printing to high-resolution devices Typically 600 – 2500 dpi, A4 image 40 MB, 16 million colours, 24-bit image Large disk space required for storing images, large RAM required for manipulating images |
Output:Usually on paper, printed at high resolutions, either in mono or 4 colours (Cyan, Magenta, Yellow, Black – CMYK), or more with spot colours, still images only |
Images can be sourced from the following: |
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Scanner: two types:
1. Flatbed — resolution up to 9600 dpi, for office/home use, good for electronic publishing.
2. Drum — used for high-end image scanning, high resolutions, industry/professional use, good for print-based publications, scans transparencies.
Note that scans taken from transparencies give better results than from a photograph; always scan at a high resolution and reduce later as appropriate, i.e. a high res scan can be used for print, and later reduced to 72 dpi for the web.
Camera: (two types)
1. Traditional - image must be scanned later.
2. Digital - image already in electronic format The photographer has to take the picture, costs could be high.
Image Library:
There are image libraries that have thousands of photographic and hand-drawn images, which can be ordered from catalogues or online, e.g. photodisc.com, gettyimages.com - low and high resolution images for both print and web, but can be expensive.
Self:
From own library, created in PhotoShop or scan of own photo - cheapest option but may not look professional unless highly skilled.
Saving images:
Original formats of images should have no compression, no loss of quality of information. Never retouch an image once it has been saved as a JPEG - you must go back to the original PSD file. Only save image as JPEG or GIF when it is ready to be put onto the web.
Software packages:(Industry Standard)image manipulation: Adobe PhotoShop (version 5.5 and above includes web-specific features, including Adobe ImageReady software) page layout: HTML coding, e.g. Notepad |
Image Formats:JPEG = (Joint Photographic Expert Group) a compressed format for photographs GIF = (Graphic Interchange Format) used for images with animations, transparency, large areas of solid colour Typically 72 dpi, file size 30 KB (A4 image 200 KB), 256 colours, 16-bit image |
Output:For computer monitors, displayed at low resolution (72 dpi), in 3 colours (Red, Green, Blue — RGB), can be still images or animated |
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Note: Bit Depth = Also known as Pixel Depth, measures how much colour information is in the image to display or print pixels. The greater the bit depth, the more colours there are and the bigger the file size. 1 bit = Bitmap 2 bit = Greyscale 8 bit = Indexed colour 24 bit = RGB |
