Ignazio, the main difference, as I understand it, is that the new one is supposed to be faster and have a larger sheet capacity (in other words, both hardware differences). The S510m is a new version that has come out since this review, and I haven’t seen it firsthand.

Wouldn’t it be great if they would release a firmware update that would bring the S500 up to the capacities of the S510? But I doubt it…

—Ed Eubanks, Jr.

I’m not being mean. Maybe it’s a left-hand-right-hand thing, but Illustrator remains, for many people, the most awkward way of making vector illustrations.

Thankfully, XPress and InDesign both have advanced bezier abilities, plus layers, transparency, and export options that make Illustrator almost unnecessary. Add in better colour control, typography, tables, and multi-pages and you arrive back at FreeHand.

—Mark Tennent

I agree, and I'll hang on to my last copy of FreeHand for as long as it will continue to run on Mac OS X.

For the love of Pete, why am I able to work with bezier shapes more easily in InDesign than in Illustrator? Shouldn't it be the other way around?

—Lee Bennett

The math isn’t really all that hard, and there are two aspects of it to consider.

First: pixels divided by PPI (that should be Pixels Per Inch, not Dots Per Inch or DPI) equals inches. In other words, whatever number is defined as your PPI (or DPI as people improperly call it) is how many pixels are going to be represented as one inch of the image, either in height or width. Thus: 10,800 (total pixels in width) divided by 600 (pixels per inch) gives you the 18 inches.

Second: more resolution does not automatically mean better. You should make a decision on how much resolution you need for a particular job. In most offset printing scenarios, the amount of resolution you were talking about is completely overkill.

I realize it may get even more confusing when you learn that commercial imagesetters for outputting film and/or plates for commercial printing run in the neighborhood of 2400 PPI and higher. These resolutions are needed for things like simple-color line artwork. Take typefaces, for example. Usually one color and maximum contrast (e.g. black text on a white background). These types of images do need more resolution, but because they have fewer colors and tend to be smaller in printed size, they don’t create a multi-hundred-megabyte file.

You say you are creating a digital painting with what I assume will be a full spectrum of colors. Thus, your image will essentially be like a photograph. The easiest rule of thumb to follow is to use a PPI value that is between 1.5 and 2 times what the halftone line screen frequency will be when the piece is commercially printed.

The halftone frequency refers to the tiny little dots used for printing. Take a magnifying glass and look at the pictures in a newspaper. Start with black-and-white photos first. Newspapers generally print with a lower screen frequency than magazines. You might even be able to see the dots with your naked eye. The distance of those dots (which are not individual pixels, by the way) is measured in terms of the halftone frequency. The measurement is Lines Per Inch, or LPI. Newspapers tend to print anywhere from around 85 to 133 LPI, though some are doing higher. Magazines, however, generally use much better (and more expensive) paper, which can handle a finer screen frequency. The higher frequencies on the paper used in newsprint usually make the ink bleed into a solid dark blob. But on the nicer papers used by magazines, you’ll generally get 150 to 200 LPI.

Back to the image resolution. I’ve pretty much always set up my pictures at 300 PPI at the final size they were to be reproduced. Years ago, my less-experienced brain told me I should go with a PPI exactly double the halftone LPI frequency. Back then, we were doing 150 LPI jobs, so I made my photos 300 PPI.

Today, I know that 1.5 times the LPI is sufficient unless the photo has some extremely fine detail in it. However, today, I’m doing all my jobs at 200 LPI. Yet, I still use 300 PPI photos (which is 1.5 times the LPI frequency).

For those photos which have much finer detail, bumping back up to double the LPI is adequate. So, for a 200 LPI frequency, a 400 PPI image will suffice.

Remember those little halftone dots you looked at with the magnifying glass? Those are the reason that any more PPI resolution is wasted—those “larger” halftone dots completely chew up any additional resolution.

Think of it as a container of new tennis balls. They come in a canister of three balls. The balls are pixels and the canister is a halftone dot. Suppose you take out the tennis balls and put golf balls inside. You now have more pixels. But, if you close the canister, you wouldn’t really know what was inside just by looking at it because the canister (the halftone dot) is still exactly the same size. So all that extra resolution inside is useless. (Unless, of course, you’re a pro golfer!)

So, lastly, how do you find out what LPI you’ll be using? Just ask whoever is doing the press work. In most cases, the press workers will generally reply with another question, “What LPI do you want?” That’s because most of them will run the job at whatever frequency you specify—within reason. Talk to them about it, but aim for a 200 line screen.

If they start talking to you about something called a stochastic screen, well, that’s an entirely different discussion which doesn’t work in terms of halftone LPI. If the press only does stochastic (and more are starting to), then stick with the 300 PPI images or 400 PPI for very fine detail images. You should be pretty safe with those.

In summary, no, you don’t need a 600 PPI image. It’s fine if you want to paint at 18×24 size just so you have a nice large image for your archive. But setting it up at 300 PPI should be quite adequate. Then, when you’re done, make a copy of it (always keep original finished images), then scale that copy down to the 9×12 at 300 PPI for your book cover.

—Lee Bennett