Scanning and preparing images for a Web site
1. Scan your material at 400ppi. Set the size, in pixels across, of the resulting file to be as large as you are ever asked for + about 10%.
2. That is your SCAN. Save this as a .TIFF (or .TIF, for Windows users). When saved, it becomes your MASTER FILE. All subsequent files will be made from it. Never make changes to it.
2a. If you are getting your image directly from a digital camera, Rule 2 still applies as do the following.
3. If you feel it is necessary to edit the image -- increase contrast, color balance, gamma, etc, open the master file, make the changes and save as a .TIF with a different name; e.g., jack_and_jill_final.TIF. This becomes your new master file and is the one you will work from.
4. Now comes the process of making image files from you master file or edited master file. Save these as JPEGs (or in Windows language, JPGs).
5. Decide how high (in pixels) you want the images on your Web site to be. 500-700 pixels is about right. The actual size in inches is something you cannot control, as there are different size monitors, set to different resolutions. Currently, most users have their screens set to 1024 wide x 768 pixels high. The height includes the top part of the screen which shows browser information and the bottom part showing other information. This means that if your image is much higher than about 500 pixels, the viewer will have to scroll up and down to see it all. It's normally best to have all the images except thumbnails or details on your site the same height
6. Save your image file as a JPG at about 75-80% (6 in Photoshop) compression (also sometimes called "quality"). Lower compression (a higher number) will preserve only a tiny bit more detail, but the resulting file will also be more bytes and thus take longer to load. A very useful program which will let you see the effects of different settings before you save the file is RIOT ( Radical Image Optimization Tool ), which can also be used as an Irfanview plug-in.
6b. Totally ignore "resolution" (dpi or ppi). This controls printers but not computer screens and is irrelevant to how your images will appear on the screen.
Resizing images with IrfanViewAssuming you have the latest version of IrfanView and the latest package of plug-ins---
1. Open your .TIF final master file. You will save these changes to a new .JPG file, the .TIF will remain unchanged.
2. Use the icon of a magnifying glass with a minus sign in it to reduce the image to a workable size (use the one with a + in it to enlarge). This does not change anything in the file; it merely changes the size of what you are looking at.
3. Crop the image as required. To do this:
6. To save it, hit the letter S. This will open a dialog to save it as a JPG or GIF. A file manager panel will also be open.
These instructions are detailed but it's actually quite easy and once you have done it a few times, it will be simple. Most of the settings you will have made in your first successful resizing and saving operation will stay set, so you will really only have to set the height with each new picture.