Rules of Thumb for Tasks

 Pictures for email.

You shouldn’t send unedited pictures in emails.  A single 2 megapixel image
straight from the camera can take twelve or more minutes to download. Then it is too
big to fit on the screen of the person you sent it to. You have not brightened their day,
but made them dread getting more pictures from you. Pictures sent via email can be
resampled down to 100 dpi, with a size of 5X7 at most. Even then that is a 350,000
byte (or over 1/3 MB) file, which could take  three minutes to download. The basic
steps to prepare a picture are:
1. Adjust brightness/contrast/intensity and hue and saturation if need be.
2. Crop image to reduce excess if desired or possible.
3. Check size and resolution of image, and resample to reasonable resolution and size.
4. Save as a JPEG or TIFF with a name that described picture contents.

Pictures for a web page.

Pictures for the web should also be cut down in size and resolution, only more so.
The same rules of thumb apply as for emails, only you will want even smaller images and
higher levels of compression. While you may have broadband, not everyone else does,
and a visitor to your site may be long gone before your home page image—or images—loads.
Follow the same steps as for preparing images for email. Many web site work programs
such as MS Front Page will tell you how long a page takes to load at a specific connect rate,
and how much load time your image will add to that wait. Pictures for a site may be saved in
 .jpg, .gif, and .png formats. Gif may compromise quality, but that format allows you to make
one color invisible.

Pictures for printing

Pictures for printing should be at the best resolution. Generally speaking, anyway.
This is where it can get tricky. So we have some sub-rules to help:

The bigger an image is the longer it takes to print. Is the picture worth waiting four
minutes for if printed so it covers the whole page?

Your printer won’t print out an image bigger than the paper it takes. If your printer is
asking if it should fit the image onto the page, then the image is larger than that page. Your
printer’s resizing may not get as good results as what you can get from your image editor.
Resize. The page will surely print faster, and probably better.

The higher resolution an image is, the longer it takes to print. Sad but true. Remember,
your picture is a file that has to be sent to the printer. The bigger the file, the longer the send time.

The resolution of your image may be greater than what your printer will support. If your
printer prints at 300 dpi in color, it will not print out a 600 dpi image for you. What it may do is
translate that image to 300 dpi, and it may not give you the same results as resampling that image
down to a resolution your printer can support.

Your color ink cartridge or cartridges will cost more and go empty faster than you
expect. Again, sad but true. It takes a lot of ink to cover a whole 8 ½ by 11 page. And if
you have a three color tank, one color is sure to run dry before the others. Learn to live with it,
and next time get a printer with separate tanks for each color.

The really expensive photo paper gives the best results. Another sad but true. But with
a bit of experimentation you may find that your printer gives decent results on one particular
brand of plain paper.

Even with good paper your pictures still may not look right. Just as different digital
cameras tend to have tendencies as to how they take pictures, maybe running a bit heavy
on reds, or a bit on the dark or washed out side, different printers have their own peculiarities.
All you can do is experiment, and learn how to adjust your images for the best print reproduction.

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