Comparing Atari XE composite video, luma/chroma and VBXE RGB

Entry posted by rdemming May 16, 2010

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Introduction

Recently there was some discussion if the VBXE's RGB output for the standard Atari 8-bit graphics modes, was really an improvement over the standard chroma/luma output of an Atari XE. Some said RGB was really better than Chroma/Luma while others claimed the Atari resolution of 320*240 or so pixels was too small to benefit from RGB.

So I decided to take some pictures of the output so you can decide for yourself. Note that the pictures look of course a little different from real life. It is not easy to take a picture of the screen because of the 50Hz refresh frequency. If the exposure time is too short, you won't see the full screen and if the exposure time is too long, then a little movement add motion blur to the picture. But I think these pictures give a good feeling of each of three possible video outputs.

For these pictures, an Atari 130XE is used with the VBXE 2 board. The 130XE was for all three video output modes connected to the same Commodore 1084S monitor. All video output modes use the same monitor settings for brightness, contrast and color.

The video system is PAL.

Bomb Jake - Title Screen

Composite video:

Chroma/Luma:

RGB:

Bomb Jake - Title Screen - Close Up

Composite video:

Chroma/Luma:

RGB:

Bomb Jake - In Game

Composite video:

Chroma/Luma:

RGB:

Bomb Jake - In Game - Close Up

Composite video:

Chroma/Luma:

RGB:

Note that with composite video, there seems a little shadowing in the picture. The transition from brown to blue is not immediate.

DROL- Close Up

Composite video:

Chroma/Luma:

RGB:

Note that the contrast in the colors is much better in RGB. With RGB you clearly see the red background in the author's name while the red is very faint with composite & chroma/luma.

Amaurote

Composite video:

Chroma/Luma:

RGB:

Amaurote - Close Up

Composite video:

Chroma/Luma:

RGB:

Note that with composite video, you have artifacting that is causing the colors in the picture. With chroma/luma the artifacting is almost gone. With RGB there is no artifacting at all and the picture is pure black/white.

MyDOS - Close Up

Composite video:

Chroma/Luma:

RGB:

Note that with RGB, the character pixels are a little bigger than with chroma/luma.

SysInfo - Small characters

Composite video:

Chroma/Luma:

RGB:

SysInfo - Small characters - Close Up

Composite video:

Chroma/Luma:

RGB:

Note that due to artifacting, the composite video output is hard to read. Chroma-Luma is much more readable but in my opinion the RGB output was the most readable.

Conclusion

It is clear the the difference between composite video and chroma/luma is great. Chroma/luma has a much better quality compared to composite video.

The difference between chroma/luma and RGB is smaller. But in my opinion RGB output has more vivid colors, the contrast is higher and the picture is a bit sharper than with chroma/luma. So for me RGB output is the winner. Except for the case of Amaurote. In my opinion the artifacting has a positive effect on the graphics. The chroma/luma & RGB output are too sharp here.