Given the reaction I described last week to my recent enthusiasm for the Mac, I sort of wish Chad Dickerson hadn’t used that word in this week’s column. However, he again points out some real positives the platform has that are of increasing importance to enterprise IT.

His story of the FireWire hard disk that konked out on two PCs but continued to work flawlessly on Macs would be a useless anecdote if it weren’t supported by countless other such accounts. If anecdotal arguments are to be of any use, surely the Mac can be regarded as a more stable platform than Windows.

He also deserves credit for not going mindlessly along with the “Mac Is Easier” line. Once upon a time it was much easier for new computer users, but this argument is probably overstated now. Windows users who switch will require retraining, and will probably not regard OS X as particularly easy as they work to learn new ways of doing things.

One brief quibble: in supporting his contention that OS X makes for a more stable desktop, he describes his experience in fixing a frozen Internet Explorer instance. Granted that the Unix foundation of OS X made this problem as fixable as it was (I normally have to reboot when things go that far south on my PC, which is quite often these days), but he did have to rely on fairly sophisticated skills to fix the problem. If running top and kill don’t sound hard to you, you need to understand that they’re way too much to expect of most desktop users. Better not to justify your claim to stability by not having things hang at all.

This quibble is ameliorated both by the realization that it was IE (a Microsoft product!) that crashed, and also by the fact that the level expertise required by a Unix/Linux/OS X user to do what Chad did is much lower than the equivalent skills required to fix a crashing Windows system. The Windows stability problem has gotten much better in the past few years, but when things go bad, you still usually need just to bounce the box.

I’d still get fired for buying Mac, but in a year or so that may be less true. I look forward with interest to the continued development of this trend.

My first moon mosaic attempt has been quite educational. I found that I am not setting the exposures correctly as the mosaic frame traverses from the fully illuminated part of the moon to the terminator, and I found that I need to come up with a new way of making sure that I cover the whole object with individual tiles. My previous process was rather ad-hoc, with unsurprising results:

View the 559×768 version (103 kB)

View the native 2374×3261 version (1.03 MB)

You can see the two small gaps I left, which are not fixable. The other problem–the obviously tiled appearance of the separate images–may be fixable, but I’m not going to invest the effort to try to rehabilitate this shot when it will never be print-quality. Besides, I’ve got a better idea of how to handle that problem next time. It turns out to be fairly tricky, and more than one additional attempt may be required to get it sorted out.

When is next time, you ask? Well, the United States Naval Observatory sez we’re three days past full now, which means Luna doesn’t rise until well after sunset, when I am normally thinking about other things, like sleep. The next first quarter is On October 2, and I’ll be taking the first clear, uncommitted night within a couple of days of that date to try this again. I would also like to do a mosaic of the full moon, but the next one is October 10, which is the first Friday after my wife’s birthday. Even if it’s a clear night, it would probably be a Big Mistake for me to plan to be behind a telescope then. (Using her laptop, no less!)

That brings us to November, which is also getting into Jupiter and Saturn season. Expect some serious fun then.

Today was a good, crisp day. Not crisp in the sense of proper fall coolness, but cool enough for late summer, with clouds that were definitely autumn-brand. Not the tall, aloof, billowing thunderheads of summer; not the low, ominous, foggy clouds of winter; but nice, teased-out cotton in a variety of shapes and colors set against a deeply saturated blue sky. There was a good breeze, and the promise of a clear evening. That was not to be.

Spring really eased into summer this year, with just the cool, wet June we needed coming out of a nasty drought. July was mostly unforgiving, as was early August, but September so far has been surprisingly cool and damp. Oh, sure, we’ll get another stray day of 90s before the month is out, but it will be an isolated interloper in the mild and friendly company of days that take us steadily up to warm fires, dark afternoons, and Christmas. Days that keep us inside, help us appreciate warmth and clothing and walls. Living isn’t easy in the wintertime, and comfort is that much more welcome then.

It is still September 10 as I write this. I may not have time to write anything about September 11 tomorrow, a shortcoming your blog bookmarks are only too likely to address. I remember September 10, though. We had just returned weeks earlier from a vacation in Pennsylvania, then an unexpected visit to Florida for the funeral of a young friend. I had just hired an engineer. School had started up. My wife was in the shower. The kids had just finished breakfast. My mother-in-law called.

Then it became September 11. We watched those buildings burn, and saw them collapse again and again. We saw men dive 100 stories to their death. We saw the burning Pentagon. We heard of a downed plane in rural Pennsylvania. We wondered how many more planes would crash that day. We thought about friends who were out of town, and how long it would be before they could return home. We sat in horror at death tolls thought to be as high as 30,000 souls. I wanted blood. Take our dead, I thought. Take them. We will come for you.

Today it is still September 12. We didn’t get the clear, cool evening we thought we had coming. Indeed, it is now very much winter for 130,000 American service men and women and their families, and spring is in many ways far off for all of us. We do have, if we can remember, the comfort of the warm fire and the dark afternoon that Providence affords us in our relative peace and safety here. October 1 felt like that two years ago. It should still feel like that now.

We didn’t get the clear, cool evening we wanted, but we do not pack up and move because of one storm. We live here, and no winter, be it early or late, is going to chase us out. Sure, we remember what the sky looked like the day before, and we were certainly taken in by its calm. Better, though, to know when the cold really comes in around here. Better to stock up the firewood, insulate the attic, enjoy the warmth and comfort. Get a blower, fit a plow on the front of the truck, push that snow back. It will be spring again soon.

And spring will come again soon. But when it comes, my calendar will still read 9/12.

Time is running out on this historic Mars opposition. I need to get in one more imaging session this week to see if I can improve things at all, but as of now, here is the best I’ve gotten. Again, I have included a single frame, the Registax-stacked frames, and the finalized image. In the case of Mars, I add a bit of histogram stretching to the wavelet filtering process described earlier in order to draw the color out more clearly. So, without further ado (images are clickable for easier comparison, but they will not be any bigger in the new browser window):

Raw Frame

Stacked Frames

Stacked, Filtered, and Stretched

I have really got to hit the sack. I’ve just spent nearly two hours processing astronomical images–time I could have spent sleeping or doing the still-substantial amount of work necessary to get comments (and lots of other important things) running here. Ah, well. Let me know by email if you like this kind of thing. And spot the Homestar Runner allusion while you’re at it.

Actually, I’m not. I just want one.

It has become more and more acceptable for Java developers to carry Macintosh laptops. I haven’t counted, but I’m pretty sure then now outnumber the Windows laptops at the typical DJUG meeting. With the advent of OS X, it’s a thing a geek can feel good about. And with the reduced need for Windows compatibility that typically characterizes Java developers, the barriers to adoption become very small indeed. Besides the extra cash required to have one.

In a company-wide meeting last week (that’s five people, all told), I allowed as how I wouldn’t mind having a Powerbook. I mean, please. Look at it! And it’s BSD Unix now! This announcement went over about like I had said that I had recently begun feeling physically attracted to other men.

But to those who cannot accept me for who I am, harken to InfoWorld CTO Chad Dickerson (blog). Chad also has decided that he likes Macs better, and can accomplish all of his day-to-day tasks on the machine just fine.

This hardly constitutes a thorough review or analysis, but it’s enough to keep me thinking. That case is titanium. It’s just one inch thick. The apple on the back of the display? Yeah, it lights up when the display is on.

<covet>I probably need one.</covet>

Took the scope and webcam out for a spin again last night. The moon is just past first quarter, which means at this time of year that it’s very low in the sky (suspiciously like what the sun will be in three months), and hard to get a good look at. I had to set up in an unusual location to get a shot that was unobstructed by trees and houses, but once I found the spot I got in a good hour of moon imaging. Mmmm, heaven.

I took forty-four individual videos in all, about 100 frames each, for a mosaic covering the entire illuminated surface of the satellite. The unregistered shareware I was trying out last night decided for some of the shots that 100 frames was too many, and instead took around a dozen. I guess I should appreciate the help, since I’m new at this, but gee whiz. This does affect results. The observant will notice some parts of the moon will be fuzzier than others when the mosaic is finally available.

That bug did expose some interesting, if expected, behavior in the digital imaging process. The whole point of image alignment and stacking is that when multiple frames of the same image are stacked, the amplitude of the images’ noise component is reduced. The signal portion of the image (that is, what the subject actually looks like, not speckles introduced by the low-cost camera electronics or waviness introduced by atmospheric distortion) then becomes stronger in relation to the noise. The more frames you stack, the better your signal-to-noise ratio, increasing in proportion to the square root of the number of stacked images. One hundred frames is therefore about three times better than ten frames.

After stacking, the most excellent Registax provides an image processing mode that allows the user to adjust the parameters of a “wavelet” filter that can bring out extra detail in the subject. You can only go so far with this before the filtering process introduces undesirable artifacts, not the least of which is accentuated high-frequency noise. You can turn up the filter to get very crisp-looking lunar mountain ranges, but for your trouble you might get very speckly-looking maria, which should be smooth and flat.

On the 100-frame shots, the signal-to-noise ratio is such that the filter can bring out a decent level of detail before the artifacts start to dominate, even on the fully illuminated parts of the moon that are traditionally very low in contrast. On the bonus ten-frame shots afforded me by this wonderful shareware tool, we had roughly 70% less joy. I was only able to turn up the filters ever so slightly before the noise started to pop right out of the picture. The resulting pictures don’t look any noisier due to having been hand-tuned with an eye towards this effect, but they are of necessity less detailed because of it.

I see that look on your face. Maybe I should explain.

First, look at the following three images (click for full 640×480 glory; new browser window will open). The first is a single, raw frame acquired from the webcam; the second is the result of Registax aligning and stacking 100 such frames; and the third is the output of a hand-tuned wavelet filter in the same program. (You have to click and drag the sliders–sliders!–yourself. This filtering business is very technical.)

Raw Frame

100 Stacked Frames

Stacked and Filtered

Hopefully you see that the raw frame is very fuzzy in detailed areas and uneven in the smooth areas. The stacked image is also very fuzzy, but edges and flat areas appear smooth and uniform. The filtered image then brings the detail back–detail which has been hitherto invisible.

The discerning eye will spot some differences in this next set. Here is where AstroVideo (no link; I’m mad at them) decided ten frames would be better than the requested 100:

Raw Frame

Merely 10 Stacked Frames

Stacked and Filtered

Numbers don’t lie. Those few shots that got shorted will be a little fuzzier than the rest in the final mosaic, but they shouldn’t diminish the overall presentation too badly.

Incidentally, I’ve spent some time in Photoshop messing with the compositing process. It’s a bit more time consuming than I had hoped, as the shutter speed and sensor gain settings had to be varied from shot to shot to maximize contrast, requiring me to adjust brightness manually on each of the 44 tiles as I align them. The final picture will be somewhere in the neighborhood of 3200×4800 pixels, and should appear to reveal a startling level of detail when scaled down to manageable sizes. I’ll be sure to share it as soon as it’s done.