Image quality? Raster pattern artifact

[phvic]

Hello! Does the image quality of the following photo look normal to you? To me solid colors look quite bad, lots of variance in luminance. A horizontal raster pattern is clearly visible where solid colors should be, even in borders. I don't know if this is normal or not, since I haven't seen output from a real vic for 20 years or so...

I've tried two different LCD displays and I'm using a composite video cable. Unfortunately I don't have a CRT monitor to test this with.

The image was too big to attach, so here's a dropbox link instead:
https://dl.dropboxusercontent.com/u/4834521/vic2.jpg

[Mike]

Even though the sample image is missing in the other thread, that's pretty much the same thing jibberjabber encountered on his VIC-20. See the thread 'Gaps between characters on video output', and the answer by me.

In short: Yes, it's quite normal. It's aggravated on most modern displays. The S-Video mod can do quite a lot to improve the display.

You should try out my program 'Colour Test' for a standard test picture, and post the screen shots here.

Greetings,

Michael

[phvic]

Michael, thank you for the speedy response! I'm very glad that it's not caused by a broken video chip

I have the same pal cr model as jibberjabber so this is most likely the cause. It is interesting that they used square wave to approximate the sine wave in the vic. Same trick is still used today on microcontrollers
I will take a closer look at the s-video mod tomorrow.

I will also try your video test program. What is the easiest way to transfer the program to my vic? I have just the vic and a Mac and a PC. No disk drive yet. I can do electronics, and if the program is not very long I can type it in too if that's the easiest way

Thank you and sorry for all the newb questions!

Petri

[Mike]

What is the easiest way to transfer the program to my vic? I have just the vic and a Mac and a PC. No disk drive yet.

If you don't have a disk drive (yet), a SD2IEC is most probably the best bet. With this device, you can use SD cards to transfer programs and disk images between PC and VIC-20.

[...] if the program is not very long I can type it in too if that's the easiest way

Unfortunately, it's not a simple BASIC program. The disk image of the tool contains some binary files, which can't easily be typed in.

[phvic]

Whoah! I made the S-Video mod and the difference is like night and day!

Here are before and after shots:
https://www.dropbox.com/sh/r6yzay1s0bpu ... o7Tt1c?lst#/

There is still some blurry vertical stripes visible in the image (hard to see in the photos). Probably caused by the 1 Mhz noise in the luminance signal as described here:
http://sleepingelephant.com/denial/wiki ... ifications

Has anyone done a combined S-video mod & CLC filter mod on the same vic?

I also ordered SD2IEC drive from The Future was 8bit, should arrive next week (fingers crossed).