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I think what we're seeing is what a high-quality somewhat idealized CRT would display given a limited-quality input signal. Whereas your memories are mostly of

I think what we're seeing is what a high-quality somewhat idealized CRT would display given a limited-quality input signal. Whereas your memories are mostly of cheap CRTs that further degrade/distort things beyond mere analog composite video signal encoding. It's definitely an interesting approach, especially for software that relies on analog signal artifacts to smooth out their dithering and blend colors.

derefr 6y ago
Right: a Professional Video Monitor (PVM) CRT—of the kind that game developers were using at the time—looks like this up close: https://d2rormqr1qwzpz.cloudfront.net/photos/2013/07/11/50075-crt4.jpg https://d2rormqr1qwzpz.cloudfront.net/photos/2013/07/11/5007... Notice the bottom-right image: the precisely-calibrated beam placement on the PVM’s shadow-mask, means that you see very defined subpixel-like regions; and yet those regions are themselves actually only partially lit, such that if you just filter for e.g. the red color-channel, you’ll see a clear, continuous waveform shrinking and expanding “behind” the red shadow-mask holes, where a signal that’s getting “brighter” as it travels is actually forming a widening cone of light within the subpixel. This is what “intensity” on a CRT actually means—less like making a lightbulb brighter; more like changing the aperture of a spotlight gobo. Yes, this is caused by the electron gun spitting more electrons; but the phosphorous molecules those electrons hit can only get so excited—so the (many) extra electrons that land in the center do nothing after a point, while the (few) extra electrons that land at the edge eventually seem to widen the beam as they begin to probabilistically excite those edge regions as well. This is what happens if you “clip” the top of a Gaussian distribution: you'll see a flat top-clipped region in the center of the distribution, that expands or contracts in size, in proportion to the number of events in the distribution. You can simulate this effect yourself in Photoshop: set a black background, then take a circular gradient of 100% white to 100% transparent (i.e. a white circle that fades to nothing), set its layer to multiply, and then copy-and-paste that layer on top of itself repeatedly. The center doesn’t get any brighter, but the circle seems to expand as the edges fill out.
- AnthonBerg 6y ago
  Good information, and beautifully put. Thank you.

derefr 6y ago

Right: a Professional Video Monitor (PVM) CRT—of the kind that game developers were using at the time—looks like this up close: https://d2rormqr1qwzpz.cloudfront.net/photos/2013/07/11/50075-crt4.jpg https://d2rormqr1qwzpz.cloudfront.net/photos/2013/07/11/5007... Notice the bottom-right image: the precisely-calibrated beam placement on the PVM’s shadow-mask, means that you see very defined subpixel-like regions; and yet those regions are themselves actually only partially lit, such that if you just filter for e.g. the red color-channel, you’ll see a clear, continuous waveform shrinking and expanding “behind” the red shadow-mask holes, where a signal that’s getting “brighter” as it travels is actually forming a widening cone of light within the subpixel. This is what “intensity” on a CRT actually means—less like making a lightbulb brighter; more like changing the aperture of a spotlight gobo. Yes, this is caused by the electron gun spitting more electrons; but the phosphorous molecules those electrons hit can only get so excited—so the (many) extra electrons that land in the center do nothing after a point, while the (few) extra electrons that land at the edge eventually seem to widen the beam as they begin to probabilistically excite those edge regions as well. This is what happens if you “clip” the top of a Gaussian distribution: you'll see a flat top-clipped region in the center of the distribution, that expands or contracts in size, in proportion to the number of events in the distribution. You can simulate this effect yourself in Photoshop: set a black background, then take a circular gradient of 100% white to 100% transparent (i.e. a white circle that fades to nothing), set its layer to multiply, and then copy-and-paste that layer on top of itself repeatedly. The center doesn’t get any brighter, but the circle seems to expand as the edges fill out.

AnthonBerg 6y ago
Good information, and beautifully put. Thank you.