[ProDigit]

Edit:

It seems that only full RED, GREEN or BLUE is at 800x600 pix.
If I would have eg dark green, the green pixel would be fully open, while the blue and red pixel would be nearly fully closed. The more open the blue and red become, the lighter the green pixel will look like to the eye, but also the more like the grey background it becomes.

Similarly, the more closed the pixels become, the more dark the green looks to the eye.

If you combine red, green and blue, and that with a white pixel, you get the background grey, not really white.

It seems I was wrong concerning the resolution.
It seems clear to me, that pure black remains at 1600x1200 pixels.
Pure RED (FF,88,88),pure green (88,FF,88),or pure blue (88,88,FF) is at 800x600 pixels.
Though these colors are very difficult to set, when the surrounding pixels only add or substract to the overall brightness of the pixel, not the contrast.

In other words, the other pixels will 'help out' the one pixel (be it red, green, or blue, or white), to increase (and put focus on) resolution (over color correctness), as well as compensate for overall pixel brightness.

Once the red has to become darker or lighter than pure red, the other pixels will compensate with their intensity, making it appear certain reds appear darker than others; while the red pixel remains fully opened. (instead of having only the red pixel get darker to control overall pixel brightness, the other pixels are doing the work)
This interpolation causes the impression of a resolution higher than 800x600 pix,of what I'd say is more like 1200x900 pixels; as it will not display 1600x1200 (eg) red pixels, but it will compensate the other 3 pixels from adding darkness to the color pixel.

I believe in computer terms this effect is called 'dithering'; actually, the opposite of dithering!
Dithering is also used in old 256 color gif animations (or old computer games), by using a grid pattern to give the impression that the image in reality has more colors than it actually has.
This method is the opposite. To use other pixels to compensate for one pixel's weakness, to increase sharpness and impression of resolution (in a distant way it's kind of like scaling a 1920x1200 pix image on a 1200x900 screen, the image is perfectly visible, but very small; and letters are readable but barely; small black lines will be visible but instead of consuming 1 pixel width (RGB), it now uses up only 2 of the 3 pixels). That's why on CRT monitors, you could get crazy-ass resolutions; and though the text became more blurry the smaller you got, you still could read at way higher resolutions than the monitor's native resolution!