Which Format?

[paul]

Hi

I use a lot of pictures on my website and just wondered the best format to use for quick loading and quality? at present i use all jpeg images at

11380 bytes
150 x 285 pixels

Loads quick enough for me but not all my customers will have broad band

Thanks

[korkus2000]

jpg is the best format for pictures, but the amount of compression is important. For pictures I usually go from 40 - 60 percent compression.

[paul]

Sorry bit of a novice, please explain commpresion?

Thanks

Paul

[korkus2000]

What software are you making the jpgs in?

[paul]

Paint Shop Pro 8

[choster]

The long answer:
A JPEG is smaller than a TIFF or BMP because it abbreviates or discards some information. The more information you discard (higher compression, lower quality), the smaller the file size, but if you discard too much your image will suffer. Graphics people use the term "artifacts" to cover the side effects of compression like blurring, distortions, or discoloration.

The trick then is to balance an acceptable level of image quality (few or no artifacts visible to the human eye) against an acceptable file size (whatever you determine is appropriate for your audience).

The compression is commonly set when you Save As (also in Photoshop when you Save for Web) as a range from 0-100%; kk2k is recommending 40-60% compression.

[limbo]

Rule of thumb for web images:

GIFs for graphic images such as logo's and those with large areas of flat colour. Good if you are converting vector based graphics.

JPEG for images contain a lot of variation in tone colour composition contract and fine deatils such as photo's.

There are many more types of graphic file types, such as TIFFs or PSD files, but apart from Bitmaps and PNG's, browsers will not support them. Including native files from Paintshop Pro (not sure of the file type - never used them myself)

Ta

Limbo

[tbear]

With paint shop pro you can export the image as a jpg, for example, and you will see a comparison window relating the amount of compression/file size/download speed(approx)/visual depreciation.
Photoshop also has this facility.
I usually try a compression value, save it, close the image and open it again to double check how it looks. The, if needs be you can make minor changes or start again......