picture file sizes

[buzybee]

Im currently uploading pictures onto a photo blog on the internet. my pictures are exceeding the limit size you are allowed to put on. how do i correct this? making my image filesize small without losing the quality?

help? im clueless!

[ACtheTROLL]

basically you can't .... it's a compromise.

large file ... lots of detail ...quite interested .... longtime to download .... can't be bothered.

not that bothered .... not much detail .... whole page onscreen in a second .... might as well have a look.

If you think about the viewer .... (this is a grossly oversimplified generalisation!!!)
a screen is generally 800x600 - 1024x768 - and your pikkies will all be viewed onscreen .... with borders ... so subtracs 100 pixels ...anything bigger is a waste

and with a modem is just frustrating .....
If you don't have a graphics editor

http://www.irfanview.net/
is simple to use, will do the job with minimum fuss.....
image | resize-resample
(you'll need to experiment with the best for you)

...... and is free (you'll probably get other suggestions too ... try all the freebies ... see which you like best)

always copy the originals .... work with the copys (just in case)

[vehelpfulguy]

There are 3 main things that control how big a digital image is:

* Number of pixels
* Dots per inch (DPI)
* Physical size

Number of pixels: All digital pictures are made up of small dots called pixels. A picture is measured by how many pixels it is wide and how many pixels high.

So a picture 1024x768 is 1024 pixels wide and 768 pixels high. Generally the more pixels in a picture the better quality the picture (assuming the cameras are the same)

Computer monitors are also measured in pixels so there is a sort of one-to-one link.

Dots per inch: This defines how many dots (pixels) there are in each inch of the picture. Obviously the more dots per inch the better the quality.

300 DPI is good quality and 10 DPI is poor quality.

(Actually dots per inch really relates to printers, but most people talk about DPI for digital pictures as well)

Physical size: The physical size is how many inches it is wide and high (6 inches wide by 4 inches high for example)

This is actually defined by the number of pixels in a picture (say 1024x768) and also the DPI.

In you INCREASE the number of pixels or INCREASE the DPI (or both) the physical picture will get bigger.

In you DECREASE the number of pixels or DECREASE the DPI (or both) the physical picture will get smaller.

more....

[vehelpfulguy]

So you can adjust three main things about a picture to change it - physical size, pixels and dpi.

To reduce the physical size of the picture you could either:

* reduce the number of pixels, but keep the DPI the same

* reduce the DPI, but keep the pixels the same.

(You could also reduce the pixels AND the DPI if you wish)

Computer monitors only display at 72 DPI so it is generally felt that reducing a digital picture to 72 DPI for screen display is a good way of reducing the file size (but you are reducing quality)

If your picture is larger than 1024 x 768 then you could also reduce the pixels to 1024 x 768.

Reducing the number of pixels and/or dpi does reduce picture quality, but it will also reduce the size of the file on disk and make it quicker to download from the web.