What is an image with values one and 255 only called?

What is an image with values one and 255 only called?

Answer 1

[Walter Roberson]

"bi-level".

Sometimes "binary" images are represented that way.

Answer 2

[John D'Errico]

I'm not at all sure why you would have stopped at 1 for the low level pixel, since it s 0 that would represent black.

ASSUMING that your image is a one channel image, this is a binary (two-level or bilevel) image, thus composed of only (almost) black and white pixels. If the image has three channels, and you can have any combination of the colors:

[  0   0   0;
   0   0 255;
   0 255   0;
   0 255 255;
 255   0   0;
 255   0 255;
 255 255   0;
 255 255 255]

for any given pixel, then this would be an image composed of the primary and secondary colors, at their maximum values.

[Anushka]

primary and secondary colors means?

[Walter Roberson]

When you have an image with two colors, the colors are not necessarily black and white. For example you can have an image created from pink and green.

The "primary" color in that case would be the color that occurs more often than the other color, and the "secondary" color would be the one that occurs less.