file size and file formats

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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 Presentation

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Page 1: File Size and File Formats

File Size and File Formats

Page 2: 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 . . . .

Page 3: File Size and File Formats

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

Page 4: File Size and File Formats

Smaller File = Better

File Size and File Formats

Smaller File = Quicker Download

JPGJPG

GIF

Page 5: File Size and File Formats

Smaller File = Better

File Size and File Formats

Smaller File = Quicker Download

256 KB3 KB

85JPG BMP

1 2

1

1 2

1

Page 6: File Size and File Formats

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.

Page 7: File Size and File Formats

File Size and File Formats

96 KB8 KB

12

45 KB4 KB

11

240 KB 20 KB12

JPG BMP

BMP JPG

GIF BMP

Page 8: File Size and File Formats

File Size and File Formats

616 KB

63 KB

9

JPG

JPG

Page 9: File Size and File Formats

File Size and File Formats

54 KB

54 KB1

JPG

JPG

Page 10: File Size and File Formats

File Size and File Formats

28 KB

237 KB

8JPG

JPG

Page 11: File Size and File Formats

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