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Dreamweaver - HTML and CSS Using Dreamweaver

Which image type?

Daniel Walter Scott || VIDEO: 8 of 34

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Introduction

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TIFF

TIFF format is an excellent choice for print but isn’t usable on the web. This is because web browsers are not able to show Tiff files.

JPEG

JPEG supports CMYK, RGB and Greyscale colour modes. It is a ‘lossy’ compression format in that the higher the degree of compression, the more data is lost. The best way to end up with a high-quality image as well as a reasonably small file size is not to save it at a lower quality level, but to ‘optimise’ it in Photoshop using ‘file > save for web’.

GIF

GIF (Graphics Interchange Format) images hold a maximum of 256 colours, making them ideal for images such as logos, maps or coloured headlines with drop shadows that are intended for display only on a website. GIF is not a suitable format for printing: while it will usually print, the results tend to be grainy and of poor-quality.

PNG 24 (32)

Portable Network Graphics (PNG) is a bitmapped image format that employs lossless data compression. PNG was created to improve upon and replace GIF as an image-file format. PNG supports greyscale and RGB. PNG was designed for transferring images on the Internet, not for print graphics, and so does not support colour spaces (such as CMYK). PNG’s are great for websites that require images with transparency. The disadvantage of PNG's is that their file size is often quite large.

Note: To get your PNG image size as small as you can without any noticeable quality changes use a website called: www.tinypng.org.

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Dreamweaver tutorial 08: Is a Gif better than a JPEG or PNG?

Hi, Welcome, My name is Daniel Walter Scott. I am a trainer here at Bring Your Own Laptop. This course is designed for people who are new to Dreamweaver and Web Design. The topic we are covering today is: What image type to use?
We are going to look at the different kinds of files that you can use on your website. The first one that you may have heard of is a ‘tiff’. This cannot be used online but it is very good for print. Those of you who are Graphic Designers coming to web design, you cannot use these online.

Basically: 
There are 3 other types of images. JPEG, GIFF and PNG.
• JPEGs are good for photography
• GIFFs are really good for logos, icons and type
• PNGs are really good for things that need a transparent backrounds

JPEG on a website

A JPEG is great for photos because it is great for colour. It has millions of colours. It uses something called a lossy format. This means that it can be used for different quality sliders. It can be scaled down, so you can lose data. It’s really good for compression. If you have used photoshop to save a JPEG, it gives a quality slider. For print you want it as high as it will go, on a website you want to keep the slider as low as it will go to keep the size down without losing much of the quality.

GIFF on a website

A GIFF only has 256 colours that it can use. The positive is that it is very small, it is also very good for text and images and logos because the way that it works, the way it is put together means that it retains a really crisp edge on things like type and logos or small icons that don’t have too many colours. It can be used for any clipart type of images that don’t have too many colours.

PNG on a website

PNGs. You don’t want to use PNG8s as these are old school. You want to use PNG 24 or 32 depending on which programme you use. It has the best of both worlds for both JEPG and GIFF. It is able to show really crisp edge type like GIFF and it has loads of colours like JPEG. The problem with a PNG is the file sizes get really big. It uses a lostless format. Unlike JPEGs lossy. Lossy means that you can lose data to get the compression down. PNGS don’t have this. A PNG is always going to be good, it’s as good as it’s going to be, there’s no low quality PNG. The problem with this is larger file sizes.

The image size / quality trade off

When it comes to web design, it is a trade off between quality and file size. If I can use a JPEG to get a smaller file size than a PNG without any visible difference in quality then I’m going to use a JPEG. The good thing about a PNG is that it has transparency. GIFF has transparency but is very very poor. It is only able to turn pixels completely see through or completely opaque. Whereas a PNG will show you multi level transparency. Great for drop shadows and things that need a transparent background. You might have an image or a photograph that needs to have a transparent background in your website.
In the next tutorial we will look at using photoshop to create these images so that you can really see the difference between these three formats.
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