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ATPM 13.09
September 2007




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Portable Power Station Review

Since preparing the above review, I have learned that Battery Geek has released a second-generation knock off MagSafe connector. To ensure that ATPM readers have as much information as possible in making their purchasing decisions, I’ve taken a look at this new iteration of the problematic component.


The connectors look almost identical, but the first-generation model on the right falls apart when disconnected from the PowerBook, and the second-generation model on the left stays together.

The second version, after being connected and disconnected repeatedly and from every angle, holds up just fine. The tip is mounted securely in its plastic housing. I can recommend it without hesitation. (In the interest of full disclosure, I should say I tested the piece only for its ability to hook up to the MacBook Pro satisfactorily and sturdily; I already gave the actual battery to my brother, who took it half-way around the world—but the battery itself was always fine.) To their credit, Battery Geek recognized the problem with their earlier design. It is too bad they didn’t contact purchasers on their own initiative, but customers can contact them to get the new version free of charge.

—Frank H. Wu


I tried my MagSafe adapter in two cars. Doesn’t seem to really work. Seems to keep the thing powered but not charging when the car is moving. Doesn’t work when the cars stays still.

—Jeff Lorber

Cars are unreliable power sources. It’s the car, not the adapter, that’s the problem. I would not count on a car to charge the computer.

—Frank Wu

A Tutorial on Resolution

Thanks for explaining that as well as you did. Several years ago I made some of the mistakes that you mentioned while scanning photos. I couldn’t find this information before scanning some photos so I forged ahead.

Knowing I wanted 8″×10″ printouts, I scanned at a very high resolution and saved the files as uncompressed TIFF files. It turns out I scanned at a higher resolution than I needed. I looked at one of them a minute ago, and it was a whopping 300+ MB file. Boy could I have used your help then.

Now on to color calibration.

—Sylvester Roque

• • •

My Panasonic Lumix DMC FZ8 snaps photos at 72ppi (JPEG), and I use Paint Shop Pro 9 to convert to 300ppi for printing, and used this example in PSP. It works great. This article helped me more at explaining PPI than any others I read and how to apply it to a printed image…thanks!


• • •

  1. Is there any way of improving—even slightly—the resolution of a limited number of pixels?
  2. As Seen on TV: how do you express, to family and friends, the “magic” infinite resolution demonstrated on the crime investigation TV shows when they enlarge a fuzzy image to crystal clarity? Does it make you want to laugh or cry?

—Paul Reitz

  1. Most people cannot discern any difference if you upscale a photo perhaps about half again bigger (e.g. from four inches to six), especially if some subtle sharpening is used as well. I’ll also admit that I’ve sometimes intentionally enlarged an image by an insane amount just for the fuzzy effect.

    There is a utility called Genuine Fractals that uses a far more complex algorithm for upscaling than Photoshop’s. But it’s rather expensive. Fortunately, an OEM copy came with my scanner at work, but you’re currently looking at $160 to buy it outright.

    In my article, I didn’t touch on the concept of line screen frequency of halftones, and I don’t care to get into too much detail here. However, for those who are familiar with the little halftone dots used to make a single ink appear like it is many tints of that color, the measurement of distance between each dot is the line screen frequency. You’ll often find that newspapers are in the 85–100 LPI (lines per inch) range, laser printers often in the 100–150 LPI range, and magazines are around 200 LPI and higher. The greater the LPI, the smoother the halftone appears. This is why you can easily see the halftone dots in a newspaper photo but not so easily in a magazine.

    The reason I say this now is because if you know what line screen frequency will be used, you can calculate the minimum resolution that should work with that frequency. I said in the article that I always send my images to press at 300 PPI. That’s because most of the items I have printed are at a halftone line screen frequency of 200 LPI. The formula is LPI × 1.5 = minimum PPI. Some people will say LPI x 2, but your mileage may vary. I’m happy with LPI x 1.5.

    Therefore, if you have a black-and-white laser printer that you know only outputs 100 LPI halftones, you only need a 150 PPI image. Any higher of resolution is probably wasted.

    I should probably also say that inkjet printers use a different form of screening than traditional halftones. It’s called stochastic screening (or FM screening, which stands for Frequency Modulation). Stochastic screening, while it can have drawbacks, usually produces results I like much better. I don’t, however, know if there’s a specific guideline for the minimum resolution that is ideal for printing on inkjet printers that are using stochastic screening. I’ve seen acceptable results on photo-quality inkjet printouts with 200 PPI images. However, while my current commercial press cannot do stochastic screens, the previous press I used (I left them for a variety of reasons) did do stochastic screens on request, and they advised 300 PPI images just the same as if I were doing traditional halftone screening.

  2. I absolutely do want to cry when I see television shows “enhance” an image in the way you describe. But then I just have to remember: it’s television, and it’s fake. I can only pray that most people watching television realize that what they see is probably not possible in real life.

—Lee Bennett

Always Use Digital Rights Protection

Even this well done article skips any clue as to why Steve Jobs utilizes DRM at all. It’s because there would be no legal sale of music or video content without it, and in case you still don’t get it, that means that none [except EMI to date] of the labels and/or producers will allow their content to be sold on iTunes or anywhere else without it. Uncle Steve’s open letter spelled that out, and when EMI found the courage to break ranks Sir Steve wasted no time in backing up his open stand on DRM by un-DRMing the only label that would allow him to.

Anyone who has ever thought that the Jobs-meister was all about using DRM to “lock” us into or out of any ability to choose our hardware of choice were just overcome by Microsoft propaganda being spewed about by the too-numerous-to-count MS “partners.”

Whatever else Jobs-and-company’s intentions were from the outset, it was clear to me that they [Apple] simply wanted get the attention of the public firmly on them [Apple] to remind people that they really do not have to use MS Windows if they didn’t want to. While I’m sure that Apple is certainly not losing money on iTMS, I doubt that it is single handedly keeping the company afloat either.

I still sit in dazed wonderment as I read articles complaining about how a consumer can only use iPods with iTunes, and I read these articles as I plug my obsolete Rio Player in and manage its music files directly inside of iTunes. And I’ve read these articles on popular blogs as recently as two weeks ago—give me a break, folks. The iTunes Music Store is one of the most ingenious ad campaigns Apple has ever come up with, and prior to the re-arrival of one Steven P. Jobs, advertising in any real way was something that Apple just couldn’t seem to pull off.

And all of the EU hoopla? Can you tell what I’m going to say next? The different pricing for different countries is about the hoops that Apple is compelled to jump through by the music labels and even the EU itself in order to even legally sell/distribute the music in those countries. Are we seeing any light here at all?

If Apple had its way it would sell non-DRMed music all over the planet for 99 cents or the exchange equivalent. Why? Because Apple is using the iTMS to get people to see them as the legitimate computer manufacturer, and a truly innovative one at that, that they are. With iTMS Apple has been doing nothing more than showing off their unprecedented ability to innovate with computing technologies in a way that offers end users conveniences that were only being talked about before iTMS—and now that Apple’s done it, everybody’s racing to get a piece.

The motivation for iTMS is really much more straightforward than anybody wants to see it—and of course, therein lies much of its genius.

—Mr. Peabody

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