file size and file formats
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File Size and File Formats. SIZE. DOES. MATTER. Digital cameras often save images in one of several formats:. JPG. BMP. TIFF. RAW. Others. - PowerPoint PPT PresentationTRANSCRIPT
File Size and File Formats
Digital cameras often save images in one of several formats:
JPG BMP TIFF RAW Others
Most of these are unsuitable for use on the web, and even JPGs (which are suitable) can be much too large or can have other issues that should be dealt with before putting them on the web.
But, most image types that are unsuitable can be made suitable, using appropriate free software (available here in the lab and at home).
There are also other sources for images, like the web itself, but just because it came from the web doesn’t mean it’s right for what you want to do. Be careful.
So what’s a suitable image type? Glad you asked . . . .
Most of the images you want to use in your web pages will be in either
JPG (pronounced jay-peg) or in GIF (usually pronounced giff)
formats. There is also PNG, but this is less common. If you’re looking at any other image type, you should consider converting it before you do anything else with it.
In general, JPGs are suitable for photos and other complex images with lots of different colors, while GIFs are suitable for simple images with few colors, large areas of single colors, or with transparent areas, or with animations. JPG images cannot have transparent areas or animations. JPGs for photos, GIFs for everything else.
JPG –Photo, many complex colors
GIF –Only a few solid colors
Smaller File = Better
File Size and File Formats
Smaller File = Quicker Download
JPGJPG
GIF
Smaller File = Better
File Size and File Formats
Smaller File = Quicker Download
256 KB3 KB
85JPG BMP
1 2
1
1 2
1
Bits and Bytes
A bit is the smallest unit of data a computer can work with, a 1 or a 0.
A byte is eight bits.
File sizes are measured in bytes, because it’s important to know how big they are – how much room they’ll take up, how long they’ll take to download, how well they’ll print, etc.
A smaller file size is better than a larger file size, but this usually means the quality of the image suffers. In general, the larger the image, the higher the quality – but the slower the download time, etc.
A kilobyte is 1000 bytes (1 KB), and is usually fairly small by web standards. Most images for the web fall into the range of about 10 KB (kilobytes) to 80 KB -- total -- for the page. Anything larger than about 100 KB -- total – for the images on a page, and you should ask yourself if there’s a better way. There usually is.
An image that needs 100 KB on disk, or 200 KB on disk, or even 1400 KB on disk, needs to be reduced (optimized) before use on a web page.
File Size and File Formats
96 KB8 KB
12
45 KB4 KB
11
240 KB 20 KB12
JPG BMP
BMP JPG
GIF BMP
File Size and File Formats
616 KB
63 KB
9
JPG
JPG
File Size and File Formats
54 KB
54 KB1
JPG
JPG
File Size and File Formats
28 KB
237 KB
8JPG
JPG
File Size and File Formats
DO USE
JPG (photos)*
GIF (solid colors, or if transparency or animation is required)
PNG (any)
*JPGs can still containlarge amounts ofinformation if notproperly optimized
DON’T USE
BMP, WMF, TIF
Other formats
CONVE
RT A
S NEE
DED