ISO 16067-2:2004 写真-写真画像用の電子スキャナー-空間解像度測定-パート2：フィルムスキャナー | ページ 6

3.1

addressable photoelements

number of active photoelements in an image sensor

Note 1 to entry: This is equal to the number of active lines of photoelements, multiplied by the number of active photoelements per line.

3.2

aliasing

reconstructed image artefacts in sampled imaging systems where the combined spatial frequency energy of the input image and scanner combination is significant beyond the half-sampling frequency of the scanner

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

3.3

digital output level

numerical value assigned to a particular output level, also known as the digital code value

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 that result in a specific imaging system producing the same output as for a spectrally neutral object

3.6

electronic scanner for photographic films

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

process that alters the image data in order to modify the tone reproduction

3.9

image sensor

electronic device that converts incident electromagnetic radiation into an electronic signal; e.g. a charge coupled device (CCD) array

3.10

resolution

measure of the ability of a digital image capture system, or a component of a digital image capture system, to capture fine spatial 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, measured in units of distance (e.g. µm, mm)

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

3.13

sampling frequency

reciprocal of sample spacing

Note 1 to entry: Expressed in samples per unit distance (e.g. dots per inch).

3.14

scanner

electronic device that converts a fixed image, such as a film 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

R_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. The SFR is normalized to yield a value of 1,0 at a spatial frequency of 0.

Note 2 to entry: In equations, the symbol R_SFR rather than the abbreviation SFR is used for clarity.

3.18

spectrally neutral

test chart in which the relative spectral power distributions of the incident and reflected (or transmitted) light are equal

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

3.21

test pattern types

3.21.1

bi-tonal patterns

patterns that are spectrally neutral or effectively spectrally neutral, and consist exclusively of two reflectance or transmittance values in a prescribed spatial arrangement

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

3.21.2

grey scale patterns

patterns that are spectrally neutral or effectively spectrally neutral, and consist 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.

3.21.3

spectral patterns

patterns that are 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.