Infographics / Image Quality

Contrast (greyscale) resolution & low-contrast detectability

A graph of object contrast on the vertical axis against object size or detail on the horizontal axis. A curved threshold line falls from top-left to bottom-right: small objects are only detectable at high contrast, while large objects are seen even at low contrast. Points above and to the right of the curve are detectable; points below and to the left are not. A second lower curve shows that more dose or less noise shifts the threshold toward the origin, so smaller and lower-contrast objects become visible.

Contrast–detail curve: threshold of detectability A graph of object contrast on the vertical axis against object size or detail on the horizontal axis. A curved threshold line falls from top-left to bottom-right: small objects are only detectable at high contrast, while large objects are seen even at low contrast. Points above and to the right of the curve are detectable; points below and to the left are not. A second lower curve shows that more dose or less noise shifts the threshold toward the origin, so smaller and lower-contrast objects become visible. standard dose more dose / less noise object contrast object size / detail high low small large detectable not detectable more dose lowers the threshold small objects need high contrast large objects seen at low contrast
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