Posted: 20/7/01 | Last modified: 20/7/01
If you can see the boundaries between subtle changes in color, then it is not a continuous tone image. In these pictures, the blue background should flow from one tone to another. In the lower quality pictures, the background is blotchy; it is easy to see where one shade of blue stops and another starts.
I reduced image 1 to 16 colors, and then saved it as a JPEG. (Technically, a JPEG never has less than 16 million colors, so I will not say that this image has only 16 colors.) I reduced image 2 to 256 colors. And the last picture is the original.
Image 3 is a continuous tone image; the others are not.
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