While I was encoding videos over the weekend, I wrote a simple little filter to average consecutive frames to produce less noisy versions of title cards. I tested it on 25 frames from the titles of The Vampire Bat.

It looks a little soft because I haven’t worked out the registration, but it nicely eliminated various frame artifacts like dust and scratches. I’ve got the silly idea that relatively simple processing like this can make relatively bad prints such as this one into more attractive prints, if not actually good ones. I’ll have to work on it some more in the future.

Addendum: This might be a good place to start with a more sophisticated version.

Well, a few minutes of Postscript programming, and I created the label on the right for my Atari 2600 programming project. In the next couple of days, I should have an EPROM programmer in hand, I’ll be able to burn my own cartridge of my Enigma simulator, stick this label on it, and call the project completed.

Then it will be time to move onto the next thing that will make my wife shake her head and wonder just how crazy I am.

Well, today I added a block cursor that I could move around (first real time I’ve written a general motion code for the player missile graphics, kind of whacky). Figured out the joystick handling and even added some primitive (and I do mean primitive) sounds.

I also picked up some real Atari 2600 hardware to go with these PC boards. I’m gonna eventually burn my creation in EPROM and run it on the original hardware.

My Atari 2600 programming projects needed two displays to enter characters on, so I built a little 5×6 matrix of characters (six characters are about the maximum you can put on a horizontal line). Progress!

I’ve been mucking around more with programming the Atari 2600, and have just begun to figure out the vagaries of moving the player missiles around.

It’s complicated.

Basically, as the video hardware scans from left to right, you set the horizontal position of a player by issuing a store to hits horizontal position register. The problem: the 6502 is only fast enough to set the position within 15 pixels of a given location. To refine the horizontal position, you need to issue a shift of -8 to +7. The timing is critical and tricky.

I haven’t really worked it all out yet, but I have players moving behind the playfield here in my example.

I think I need to carefully work out the timing on paper before doing anything more refined.

Addendum: Not really sure where that little black bar is coming from either.

From time to time, I get this curious nostalgia for the computers of my youth. Don’t get me wrong: I love having megaflops to burn, and would gleefully accept more. But sometimes I hearken back to the simpler days of my youth and my first computer: an Atari 400 that I bought with the money I earned by mowing lawns and cleaning the volcanic ash from Mt. St. Helens out of gutters. My old Atari was actually a pretty fun machine with a flexible, powerful (for its day) video architecture. The entire OS ROM was (if memory serves) 10K of 6502 assembly code, and I got hold of the assembly source for it, and read it front to back, studying it for its mysteries.

Over the past couple of weeks, I decided to set my clock back even further, and learn how people programmed the Atari 2600: the first programmable video game that became truly popular. I had forgotten just how primitive the thing was:

• 1.19 Mhz 6507 processor (like a 6502, but with only 4K of addressable memory)
• So called “player missile graphics”, two 8 bit wide sprites and two one bit wide missiles
• No framebuffer: all backgrounds are generated “on the fly”

And yet, people made lots of games for these things. In that spirit, I set out to implement a simple game. I haven’t really gotten two far in a couple of hours of programming, but on the right you can see a screen dump of a title screen that was actually generated by writing assembly code, assembling with p65, a 6502 assembler written in perl and then running the binary image on Stella, a 2600 emulator.

I’ll yap about some of the technical details in this evening’s podcast. If you are interested in this gunk, tune in!

Addendum: Josh reports that he’s getting my “don’t steal bandwidth” image when reading this feed in bloglines. I just checked my own bloglines subscription, and it appears to be working fine for me. Is anyone else having problems seeing linked images in bloglines? I put in a special exception for bloglines, so there shouldn’t be any problems (that is, if my weak understanding of how all this stuff works is actually correct). Drop me an email if you are still having difficulties.

The other day I was watching TV and saw an advertisement for One a Day Weight Smart Vitamins. Most of the diet plans that I’ve seen lately recommend augmenting your diet with vitamin supplements, something that I’ve done only irregularly through my year and a half attempt to reduce my weight. Since I was out of vitamins, I trudged down to Long’s and picked up a bottle. The selling point of this particular brand is that it contains EGCG (green tea extract) which they claim enhances your metabolism, and doses of chromium, selenium and B vitamins. I was curious about EGCG’s effects on the body. Studies have shown that consumption of green tea can have lots of good health benefits, including effects on inhibiting the growth of certain cancer tumors and possibly effects on luekemia. But I found it relatively hard to find data on the effects on diet and metabolism. The best link I found was:

Yahoo! Health Ask the Expert: Dr.Weil’s All Q&A’s > Can a Green Tea Component Promote Weight Loss?

Despite its many beneficial effects, I know of no good evidence to suggest that EGCG promotes weight loss. A study at the University of Chicago did show that rats injected with EGCG lost their appetites and ate up to 60 percent less than normal, but there was no effect on the rats’ appetites when they were given EGCG orally. The researchers who conducted the study speculated that long-term oral administration of EGCG might have the same effect on appetite as the injections but cautioned that humans would have to drink green tea constantly to get the results seen in the animal study. Furthermore, the EGCG injections caused hormonal changes in the rats that could have negative effects on health if they occurred in humans.

In other words, pretty speculative effects for weight loss. Dr. Weil does recommend drinking green tea, which (because you are consuming multiple cups of a liquid) probably does help you eat less, and has other proven health benefits.

Finding good information about diet is still really difficult.