How to decrease the image file size?

[pat brennan]

hi Viana, Irfanveiw is free and easier to use for resizing

[Colin Southern]

I could be confused with PPIs and bytes. The resolution is also 72.

Resolution is irrelivant when displaying on a monitor, as the monitors resolution is fixed. Most monitors today have a resolution of around 90 PPI, but all that means in terms of image sizing is that the higher the monitors PPI, the smaller any given image will display (when displayed at 100%) (ie 100% means 1 image pixel for 1 monitor pixel).

This confuses a LOT of people - the best possible advice I can think of is FORGET ABOUT PPI WHEN RESIZING IMAGES FOR THE INTERNET - the ONLY thing you really need to worry about is the number of pixels in the image. In terms of posting images here (and this advice is also valuable for inline photo galleries), something with the long dimension being in the order of 800 pixels is pretty much the minimum if you want people to be able to see the quality of the shot. 1000 pixels is "nicer", and 1200 pixels (still talking long dimension here) is nicer still (I've traditionally done mine to about 1024, but am moving up to 1200 from now on).

In terms of file sizes - personally - I aim for 500kb. Even at a larger 1200 x 800 pixel image size, the file size should still be in the order of 400 to 500kb if one saves with a Photoshop quality setting of 10 (any higher just makes for a bigger file, but you won't be able to see the difference).

[Canonman13]

Resolution is irrelivant when displaying on a monitor, as the monitors resolution is fixed. Most monitors today have a resolution of around 90 PPI, but all that means in terms of image sizing is that the higher the monitors PPI, the smaller any given image will display (when displayed at 100%) (ie 100% means 1 image pixel for 1 monitor pixel).

This confuses a LOT of people - the best possible advice I can think of is FORGET ABOUT PPI WHEN RESIZING IMAGES FOR THE INTERNET - the ONLY thing you really need to worry about is the number of pixels in the image. In terms of posting images here (and this advice is also valuable for inline photo galleries), something with the long dimension being in the order of 800 pixels is pretty much the minimum if you want people to be able to see the quality of the shot. 1000 pixels is "nicer", and 1200 pixels (still talking long dimension here) is nicer still (I've traditionally done mine to about 1024, but am moving up to 1200 from now on).

In terms of file sizes - personally - I aim for 500kb. Even at a larger 1200 x 800 pixel image size, the file size should still be in the order of 400 to 500kb if one saves with a Photoshop quality setting of 10 (any higher just makes for a bigger file, but you won't be able to see the difference).

Thanks Colin for clearing it up.