ISO 16067-1:2003 写真—写真画像用の電子スキャナーの空間解像度測定—パート1：反射媒体用スキャナー | ページ 6

3.1

addressable photoelements

number of active photoelements in an image sensor equal to the number of active lines of photoelements, multiplied by the number of active photoelements per line

3.2

aliasing

output image artefacts that occur in a sampled imaging system for input images having significant energy at frequencies higher than the Nyquist frequency of the system

Note 1 to entry: These artefacts usually manifest themselves as moiré patterns in repetitive image features or as jagged “stairstepping” at edge transitions.

3.3

digital output level

digital code value

numerical value assigned to a particular output level

3.4

edge spread function

ESF

normalized spatial signal distribution in the linearized output of an imaging system resulting from imaging a theoretical infinitely sharp edge

3.5

effectively spectrally neutral

having spectral characteristics which result in a specific imaging system producing the same output as for a spectrally neutral object

3.6

electronic scanners for photographic prints

scanner incorporating an image sensor that outputs a digital signal representing a still print image

3.7

fast scan direction

scan direction corresponding to the direction of the alignment of the addressable photoelements in a linear array image sensor

3.8

gamma correction

signal processing operation that changes the relative signal levels in order to adjust the image tone reproduction

Note 1 to entry: Gamma correction is performed in part to correct for the nonlinear light-output versus signal input characteristic of the display. The relationship between the light input level and the output signal level, called the OECF, provides the gamma correction curveshape for an image capture device.

Note 2 to entry: The gamma correction is usually an algorithm, look-up table or circuit which operates separately on each colour component of an image.

3.9

image sensor

electronic device that converts incident electromagnetic radiation into an electronic signal

3.10

resolution

measure of the ability of a digital image capture system, or a component of a digital image capture system, to depict spatial picture detail

Note 1 to entry: Resolution measurement metrics include resolving power, limiting visual resolution, SFR, MTF and CTF.

3.11

sampled imaging system

imaging system or device which generates an image signal by sampling an image at an array of discrete points, or along a set of discrete lines, rather than a continuum of points

Note 1 to entry: The sampling at each point is done using a finite-size sampling aperture or area.

3.12

sample spacing

physical distance between sampling points or sampling lines

Note 1 to entry: The sample spacing may be different in the two orthogonal sampling directions.

Note 2 to entry: It is measured in units of distance (e.g. micrometres, millimetres).

3.13

sampling frequency

reciprocal of sample spacing

Note 1 to entry: It is expressed in samples per unit distance [e.g. dots per inch (DPI)]

3.14

scanner

electronic device that converts a fixed image, such as a print or film transparency, into an electronic signal

3.15

scanner opto-electronic conversion function

scanner OECF

relationship between the input density and the digital output levels for an opto-electronic digital capture system

3.16

slow scan direction

direction in which the scanner moves the photoelements (perpendicular to the lines of active photoelements in a linear array image sensor)

3.17

spatial frequency response

SFR

measured amplitude response of an imaging system as a function of relative input spatial frequency

Note 1 to entry: The SFR is normally represented by a curve of the output response to an input sinusoidal spatial luminance distribution of unit amplitude, over a range of spatial frequencies, and is normalized to yield a value of 1,0 at a spatial frequency of 0.

3.18

spectrally neutral

exhibiting reflective or transmissive characteristics which are constant over the wavelength range of interest

3.19

test chart

arrangement of test patterns designed to test particular aspects of an imaging system

3.20

test pattern

specified arrangement of spectral reflectance or transmittance characteristics used in measuring an image quality attribute

Note 1 to entry: The test pattern spectral characteristics include the types given in 3.21.1 to 3.21.3.

3.20.1

bitonal patterns

pattern that is spectrally neutral or effectively spectrally neutral, and which consists exclusively of two reflectance or transmittance values in a prescribed spatial arrangement

Note 1 to entry: Bitonal patterns are typically used to measure resolving power, limiting resolution and SFR.

3.20.2

grey-scale patterns

pattern that is spectrally neutral or effectively spectrally neutral, and which consists of a large number of different reflectance or transmittance values in a prescribed spatial arrangement

Note 1 to entry: Grey-scale patterns are typically used to measure opto-electronic conversion functions.

3.20.3

spectral pattern

pattern that is specified by the spatial arrangement of features with differing spectral reflectance or transmittance values

Note 1 to entry: Spectral patterns are typically used to measure colour reproduction.