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MEM Driving Miss Digital

Spatial Frequency

Topics Covered: Spatial Frequency Cycles vs Lines vs Dots per mm Why does the eye see a thing more clearly in dreams than the imagination when awake? – Leonardo da Vinci Very simply put, the number of lines that fit a certain space defines the spatial frequency of the lines. If one can cram in […]

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MEM Driving Miss Digital

The Sine Grating

Topics Covered: On the nature of Edges and Boundaries The Sine Grating The eye altering, alters all – William Blake There are no sharp edges in the absolute sense. If you zoom in close, even the sharpest edge will become smooth at some point. If you zoom out far enough, even the smoothest of edges […]

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MEM Driving Miss Digital

What Noise Does

Topics Covered: Noise Signal-to-Noise Ratio Noise proves nothing. Often a hen who has merely laid an egg cackles as if she laid an asteroid – Mark Twain “Noise is always unwanted,” declared Dr. Optoglass. “But sometimes it fools us into thinking its existence is warranted.” “I see you are not a believer in noise, Dr. […]

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MEM Driving Miss Digital

At the Edge of Acutance

Topics Covered: Acutance or Edge contrast Local contrast vs Global contrast People see only what they are prepared to see – Ralph Waldo Emerson “Yes, the eye can be cheated,” sighed Dr. Optoglass. “You’ll find visual tricks everywhere, so I don’t have to convince you of that. Sometimes the eye makes something look worse than […]

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MEM Driving Miss Digital

The World of Contrasts

Topics Covered: What is Contrast? Contrast Ratio and Dynamic Range Contrast is what makes photography interesting – Conrad Hall “You like boundaries and edges, don’t you?” quizzed Dr. Optoglass. He can see through me, thought Bob. “They are interesting, I guess.” “More than that, my dear boy. They are absolutely necessary. Did you wonder why […]

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MEM Driving Miss Digital

Image Resolution

Topics Covered: Resolution and Detail The Optotype The Resolution of the Human Eye at 20/20 vision “There are people who have been tested at 20/8 vision, and 20/12 vision is quite common. But that’s nothing compared to hawks – they supposedly have 20/2 vision.” Another long intake of breath by Dr. Optoglass. He was like […]

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MEM Driving Miss Digital

Defining Sharpness

Topics Covered: Defining sharpness Visual Acuity The Snellen Chart Dr. Optoglass opened a drawer, and removed a scalpel. “Okay, Bob. How sharp is this knife?” Bob examines the scalpel. “Pretty sharp.” “Would you say it is sharp enough to cut your finger?” “Sure.” “I’ve got a quotation for you:” I believe there’s nothing more disturbing […]