Whether you have off-the-shelf software
or the came-with-the-computer software, great-looking, non-crunchy JPEGs
can be yours with the click of a button and just a little patience. Depending
on which version of software you own, you may need more or less of the
patience part.
What Are "Crunchies"
and Why Are They Evil?
Those are the little abnormal pixelations that can be seen in a low-quality
picture. They're evil anytime they detract from your image, especially
if it started out as a great-looking one but got mangled somewhere in
between scanning and saving it as a JPEG.
A photo-editing program, any program, will only get you
so far. It's also going to take a good eye and discernment to choose the
best balance of image quality, file size, and download time. And no crunchies.
Using Adobe Photoshop
The benefit of making your graphics with Photoshop is that you can proof
your results, compare, and tweak them, all before you save.
Photoshop gives you the option to "Save For Web"
(File/Save For Web) which lets you preview the original against
versions of proposed images, the file size, the quality, and the approximate
time it will take to download.
» Click here for image.
In this case, the version chosen was the upper right one
(bordered). Its quality is good and it's only about 12K. In the bottom
left corner is the file saved at the highest quality, which doesn't look
noticeably better than the 12K version but is over three times as large (and
will take three times longer to download). In the lower right corner is 0
quality — while I'm doing this for emphasis, the crunchy and blurry
edges of this one just won't work.
Using Microsoft Photo Editor
Open or create your image in Photo Editor. Once you're ready to make it
a JPEG, choose File/Save As and then choose to save it as a JPEG.
But before you hit "Save," click the "More" button
in the lower left corner.

"More" opens up the box to more options:

The first option is set to Gray Scale, which is fine, since
that's what my image is. I get no choice with the second; JPEG compression
is what you get (you are, after all, making a JPEG file, right?).
The quality factor slider is what we want to concentrate
on here. I've made my image 9 for a truly low-quality JPEG experience.
Now click Save.
But my image on the screen looks exactly the same (and pretty
darn good). So what did I really change?

This is the tough part… you're not really viewing the
file you just saved. In order to get the full view, you need to preview
it in an HTML file. And then you will see its low quality in all its crunchy
glory:
» Click here for image.
Yuck.
So the only answer is to experiment. The right quality
to save as will differ for every single JPEG you make. Dragging
the slider all the way to the right may get you a great-looking JPEG with
a hefty file size of 40kb — not the greatest tradeoff either. This
is not to say you can't make high-quality JPEGs using Photo Editor —
but it will require diligence and patience to get the desired result.