The TRS-80/Tandy Color Computer SuperSite! » Graphics

320 Pixel Mode Artifact Samples

Potatohead — Fri, 26 Mar 2010 05:56:59 +0000

These are some captures from Jason’s work trying out various palette settings. The color spaces on these are really good, and clearly get over the 256 color limit overall. Mostly this is a good option for different screens, where one could be brighter, or optimized for motion, or darker, etc… However, if mid-screen palette register changes were used, or different palettes for different screens are used, the number of colors possible on the screen gets pretty high, and likely to easily hit 1K colors displayed at one time, with no flicker, just vertical limits, where the palette registers are changed. Probably only good for pictures, though one or two changes could break the screen into zones, and still be useful.

I didn’t expect this good of a color space!

I’ll let Jason link this, and the disk image that generated these. FYI, each pair of screens is captured with the phase bit set to either one or zero, showing the color space change on phase change. From my quick inspection, the colors are actually the same, for the screens where the brightness is the same.

One advantage of this mode is 16 “real” colors are available. Just plot two pixels together, and there will be few to no artifacts. What that means is objects can be moved at 320 pixel resolution, so long as it’s composed of sets of two 320 mode pixels that are the same color. Effective resolution of the moving images is still 160 pixels, but with better precision in placement.

Doing this will incur some color clash, if done on a non-black background, the amount of this depending on how much color contrast there is.

Moving objects drawn with artifact colors, where sets of two pixels are not the same color, will need to be positioned at the one byte per pixel, or 160 pixel resolution, to prevent color shifting on motion.

IMHO, a careful palette selection to maximize this would yield less than 256 useful colors, but allow for better precision on moving objects. Of course, this is all a choice that can be changed at any time! This pixel mode has some advantages over the 640 pixel one, IMHO.

Good job on checking out palettes!

This post was submitted by Potatohead.

256 Artifact Color Slideshow Demo

joel.ewy — Mon, 04 Jan 2010 18:47:30 +0000

Dig out that old composite monitor! Pull that analog TV off the trash heap! Here’s a demonstration of 8-bit artifact colors on the CoCo 3. Are there really 256 distinctly identifiable colors? I’m not sure, but there are definitely way more than 16.

In case you haven’t read the recent posts (and you should), Potatohead, Jason Law, Briza, and Robert Gault have been working on palettes and sprite routines that work on the CoCo 3′s 640x200x4-color screens, rendering an effective 160×200 image in approximately 256 colors. These artifact colors work just like the artifact colors we are familiar with from the CoCo 1/2′s 256x192x2-color PMODE 4, but there are a lot more colors. Working together, they have come up with a palette file that approximates these artifact colors.

I used this palette file in the GIMP to convert some images I found on flickr.com and elsewhere on the Internet into a slide show that demonstrates this pseudo-mode. The pictures are mainly of airplanes, ships, castles, and people (only some of whom are dressed up like orcs and goblins), and were selected to demonstrate some of what could be done with this method of graphics display. I was thinking about graphical adventure games, so that went into my image searches. But since this uses no fancy palette switching or screen flipping, it could be used for arcade games as well.

To view this slideshow, you will need Drivewire 3, a 512K CoCo 3, and an NTSC color composite monitor or TV. Just pop the disk image in drive 0 of your Drivewire server and type ‘DOS’ in HDB-DOS. If there’s interest, I will produce a version that is bootable from a real 720K floppy disk — unless someone else beats me to it. (Feel free!) I tried it on a 128K CoCo 3 but couldn’t get it to work. I’m not sure whether view (or another .VEF viewer) can be made to work in 128K or not. The system could certainly be trimmed of unnecessary modules to free up memory, but I don’t know whether that could yield enough extra memory for a graphics program and 32K of picture data, but it may be possible.

The images are uncompressed .VEF files. Since all but one are photos, I don’t think most of them would compress very well, though some have some borders to compensate for portrait mode. Those borders might crunch down pretty well.

Even if you can’t boot the disk image, you should be able to view the images from OS-9. They are stored as standard .VEF files. Boot (Nitr)OS-9, cd to the root directory of the disk image, and type ‘runshow’. You will need the ‘view’ utility somewhere in your path. A copy of it is in the CMDS directory of the distribution disk image.

Enjoy.

JCE

Drivewire >128K CoCo 3 256-slideshow_dw3.zip (479 KB)

720K Floppy >128K CoCo 3 256_Slideshow_720.zip

This post was submitted by joel.ewy.

Move Dot

JitterBug — Wed, 09 Dec 2009 04:51:43 +0000

Hi, I’m Brand New Here, And Want To Write A Program. I Get The Basic Commands(Parddon The Pun:) ) Anyway, How Can I Make A Small Black Dot, Then Use A Joystick To Move It Around The Screen.

This post was submitted by JitterBug.

Best Coco 3 Picture viewer with slide show?

mrnukem — Mon, 29 Jun 2009 05:58:45 +0000

I am looking for information on what would be the best coco 3 picture viewing software with a slide show function if possible. I have lots of disk images with CM3, P11, P14, GIF, Mac, H01 but have not been able to find much in the way of picture viewing software.

If anyone can get me a program title or a disk image or 2 with the viewer that I am looking for I would be grateful.

Thank you