VCT 308 week2
Terms
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- Bitmap
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A binary representation of an image, in which each bit is mapped to a point(pixel) on the output device where the point will either be on or off.
An image formed by a rectangular grid of pixels, each one of which is assigned an address as x.y coordinates and values, either grayscale or colour - Byte
- The standard unit of binary data storage in computer memory or disc files. A byte containing 8 bits can have any value between zero and 255
- CCD
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(charged couple device)
A solid state image pick up device composed of rectangular matrix or single row of light sensitive picture elements - CMOS
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( complementary metal oxide semiconductor)
an alternative imaging sensor to the CCD, which can contain more processing functions in its architecture. it converts the signal to a digital value within each pixel in a single step. it requires less power than the CCD and its cheaper to manufacture. - Digitize
- Convert into digital form. Digitalation is subdivided into the processes of sampling the analogue signalat a moment in time, quantizing the sample and coding the number in binary form.
- Dither
- A method of making digitized images appear smoother using alternate colours in a patter to produce a new perceived colour.
- Down-Sample
- To reduce the resolution of an image.
- Effective Pixel
- The actual number of pixels involved in the recording of an image.
- FM Screen
- An alternative to conventional screening that separates an image into very fine, reandomly placed dots as opposed to a grid of geometrically aligned halftone cells. it is similar in concept to mezzotint.
- Halftone
- The process of printing continuous tone photographic images by simulating the continuous tone with a series of dots of varying sizes.
- Image Resolution
- Digital images from digital cameras or scanners are composed of a square or rectangular grid of pixels. The resolution of digital images in quoted in the number of pixels per (linear) inch, or the total number of pixels in a image. usually millions of pixels.
- Image Sensor
- An image sensor contains a grid of minute light sensitive pixels (photosites) which act like a photogenerated light meter, measuring the amount of light falling upon them and generating an electrical current in proportion to its intensity.
- Index Color
- A single-channel image with 8 bits of colour information per pixel. the index is a clut containing up to 256 colours. This range of colours can be edited to include only those found within the image. Digital images in multimedia programs are often in indexed colour mode.
- Jaggie
- Refers to displays of bitmapped images, where both curved and diagonal straight lines appear to be jagged are composed of square pixels.
- JPEG
- A widely used lossy compression routine for the storage of still photographic images. Users can specify the amount of compression used when saving the image
- Line Art
- The term given to diagrams consisting of black lines on a white background, or vice versa
- LPI
- The scale used by printers when specifying the halftone screen used in a printing process.
- Mega Pixel
- One million pixels
- Pixel
- The term derived from picture element, usually taken to mean the smallest area capable of resolving detail in an image sensor such as a ccd array
- Posterize
- traditionally a photographic printing method of reducing a continuous tone monochrome or colour image to a predetermined number of tones, each of which is a uniform tone or colour value. typical posterizations will have between three to five tones.