Web graphics?

[visagephoto]

Could anyone advise, what's the best format for saving photo's and graphics to be included on a website. jpeg, gif. etc.?

[Coding Monkey]

Generic question, generic answer: depends what the images are. I'd generally say photo's in jpeg, graphics in gif, but it can vary.

[Tin]

In similar situations my criteria is filesize & image quality jointly. Sometimes jpegs suit the purpose perfectly and others suit gif's. Colour depth has quite a bearing on which format becomes most economical to use whilst keeping quality in mind.
Essentially, it's up to you and your expectations to decide the balance between download speed and image quality and this can be influenced by your market sector, after all 'a picture is worth a thousand words' :-)

I don't know whether that adds to anything already said or not :roll:

[visagephoto]

Thanks guys,

I noticed when saving for web display in PS there are a number of different formats, each with a choice of settings, colour depths, interlaced and non interlaced etc.

I guess I'll just stick to plain old jpgs & gifs.

[JoyDivision]

JPEG - 16 Million colours but is a lossy format, e.g the more you compress it the more the quality fades.

GIF - 256 colours but is a lossless format, you cannot tell the difference between a BMP or GIF providing less than 256 colours are used in the original.

As already said JPEG for photos, GIFs for graphics.

[Sapphire-Limited]

Hello,

I would prefer to use .png format where possible.

Here's a link to explain why:

http://en.wikipedia.org/wiki/PNG

Regards
Gareth
Sapphire Document Solutions

[Mortime Business Software]

Just to add to JoyDivision's answer, and assuming 8 bits to one byte, you can think of a JPEG pixel as using 3 bytes to represent one of 2^24 = 16,777,216 colours, whereas a GIF pixel uses only 1 byte to represent one of 2^8 = 255 colours. That is, each pixel of a JPEG graphic is capable of repesenting a much greater range of colours than each pixel of a GIF graphic.

You will have noticed that if you convert a JPEG image with many different colour values (a photograph) into a GIF image, there is a noticable loss of quality. This is because each pixel of the GIF cannot represent as many colours as each pixel of a JPEG, and has to use an "average" (for want of a better expression) for blocks of similar neighbouring pixels.

Also, I've seen JPEGs compressed to 50% without too much loss of quality. This is because compression involves the subtraction of blocks of neighbouring pixels with slightly different colour values (binary values), and replacing them with just one binary value in the file.

So it is up to you to consider...
> the size of your image files,
> the time it takes to transmit their information across the network,
> the quality of image you want,
> the different transmission speeds of the various types of user connection.

Dave

[DavidHorn]

PNG is a good format - but transparency in PNG's is not yet well supported in Internet Explorer. IE6 does not support transparency in PNG which means that using it as a format on the web can have different results across browsers.

Generally, if your images have lots of tonal variations (e.g. photos), go with JPEG. If the images are more like blocks of colour (e.g. logos), go with a GIF.

Both image formats are 100% browser friendly.

[JoyDivision]

That is why I am not using PNG at the moment although I think it will be soon time for me to make the switch giving that the vast majority of browsers now support PNG.