Resizing/resampling images using Irfanview
NB: my camera is set to 3:2 (for digital prints) not 4:3, hence the unusual resize values. Also please disregard my medicore afocal moon shot used in the example. Screenshots taken from Irfanview 3.92 using default values.
1. Download Irfanview from
http://www.irfanview.com/main_download_engl.htm and install it.
2. From the 'File' menu, select 'Open'. Locate your file and click 'Open'.
http://users.on.net/sjeriksson/img/i...esize/open.jpg
3. From the 'Image' menu, select 'Resize/Resample'.
http://users.on.net/sjeriksson/img/i...zeresample.jpg
4. Using the 'Set new size:' option, enter the width or height that you want the image to be. If you leave the 'Preserve aspect ratio' option selected it will automatically maintain the height/width ratio of your image, so you should only need to enter either the width or the height. Leave the other default options alone.
http://users.on.net/sjeriksson/img/i...e/picksize.jpg
* Tip: Generally most Internet forums prefer images to be no larger than 800x600, with 640x480 generally suggested and used (for 4:3 images).
5. Once you have picked a new size for your image click 'OK'. Your image is now resampled/resized and ready to be saved.
http://users.on.net/sjeriksson/img/i.../resampled.jpg
6. From the 'File' menu choose 'Save as'. From the 'Save Picture As' screen, locate the folder where you wish to save your newly resampled/resized image. To avoid saving over your original image, either save the image to a new folder, or with a new name. From the 'Save as type' option choose 'JPG - JPEG Files'. You will notice that there is now an extra window to the right titled 'JPG/GIF save options'. The only option you need to play with is the 'Save quality' slide bar (leave the other default values if you are unsure). The default of 80 should be fine for most images, however this can be adjusted to suit.
http://users.on.net/sjeriksson/img/i...ize/saveas.jpg
Using this method I was able to get my average moon shot down from 270KB (2304x1536) to a more favorable and forum friendly 30KB (640x426).