visual sharpness
11Test, visual acuity — This test measures how well you see at various distances. It is the familiar eye chart test. The eye chart itself the usual one is called Snellen s chart is imprinted with block letters that line by line decrease in size, corresponding to the… …
12Acuity, visual — The clarity or clearness of the vision, a measure of how well a person sees. The ability to distinguish details and shapes of objects; also called central vision. The word acuity comes from the Latin acuitas = sharpness …
13photography, technology of — Introduction equipment, techniques, and processes used in the production of photographs. The most widely used photographic process is the black and white negative–positive system (Figure 1 >). In the camera the lens projects an image of… …
14contact lens — one of a pair of small plastic disks that are held in place over the cornea by surface tension and correct vision defects inconspicuously. Cf. hard lens, intraocular lens, soft lens. [1885 90] * * * Thin artificial lens worn on the surface of the …
15Giant Sable Antelope — Taxobox name = Giant Sable Antelope status = CR status system = iucn2.3 trend = down image width = 250px regnum = Animalia phylum = Chordata classis = Mammalia ordo = Artiodactyla familia = Bovidae subfamilia = Hippotraginae genus = Hippotragus… …
16visualacuity — visual acuity n. Sharpness of vision, especially as tested with a Snellen chart. Normal visual acuity based on the Snellen chart is 20/20. * * * …
17Depth of field — The area within the depth of field appears sharp, while the areas in front of and beyond the depth of field appear blurry …
18Circle of confusion — For the closely related topic in microscopy, see Point spread function. In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as… …
19photography, history of — Introduction method of recording the image of an object through the action of light, or related radiation, on a light sensitive material. The word, derived from the Greek photos (“light”) and graphein (“to draw”), was first used in the… …
20Acutance — An image with artificially increased accutance Another illustration, where overshoot caused by using unsharp masking to sharpen the image (bottom half) increases acutance. In photogra …
