What does ‘rastered by cathode-ray colour’ mean?

The passage below is from Fathoms: The World in the Whale Hardcover by Rebecca Giggs.

The boundary between cultural artifact and wild thing grew blurry in these contexts. Animals were globally muddled: birds from several sites might share an aviary; ‘the tropics’ and ‘the desert’ were genres without geographic distinction. The captivations of the BBC’s Kingdom of the Ice Bear (1985) meant we wore through the videotape, stranding the polar bears on snow banks rastered by cathode-ray colour (a deterioration eerily clairvoyant of the great dissolving that would befall their habitats in decades to come).

1st question. In this passage, ‘we’ saw the BBC videotape on Ice Bear so many times to wore it out. And its wearing out makes it seem polar pears on the video to be stranded on snow banks. (Am I right?)

2nd question, on the role and meaning of ‘rastered by cathode-ray colour’.

Based on the 1st question, I decided that this phrase explains how polar pears seeming stranding on snow banks happens. (Am I right?)

That is, specifically, by being rastered by cathode-ray colour. (Am I right?)

3rd question, the meaning of raster. Merriam Webster offers a noun meaning:

a pattern of closely spaced rows of dots that form an image. But I don’t have any visual grasp of this phrase, ‘rastered by cathode-ray colour’. Can you tell me what’s going on this replayed-so-many-times-that-something-happened BBC videotape?

Thanks in advance.


You are probably familiar with flat-screen TVs.

In the old days, before flat-screen TVs, there were Cathode Ray Tubes.

The images were "painted" on the screen by electron beams, which stimulated tiny areas called "pixels". A pixel was composed of three colors, red, green and blue. A color CRT has three electron guns, one for each color.

One horizontal line of pixels is a raster.
Rasters are spaced close together to make an image.

Cross-section of CRT:

Pixel pattern on color CRT (magnified) with image of mouse pointer.


They played the videotape on a player that was connected to the TV. The tape wore out so the image became very faint and indistinct on the screen. The seemed to be frozen, not moving, on the snow banks.

Students: We have free audio pronunciation exercises.

Thanks a lot as always, AlpheccaStars.

You image and explanation gives me a clear picture of the sentence. Thanks.

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