YY/T 1603-2018 PDF English
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YY/T 1603-2018: Medical Endoscopes - Endoscope Supply Units - Video Camera System---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/YYT1603-2018
YY
PHARMACEUTICAL INDUSTRY STANDARD
ICS 11.040.99
C 40
Medical Endoscopes - Endoscope Supply Units -
Video Camera System
Issued on. JANUARY 19, 2018
Implemented on. JANUARY 01, 2019
Issued by. China Food and Drug Administration
Table of Contents
Foreword... 3
1 Scope... 4
2 Normative References... 4
3 Terms and Definitions... 4
4 requirements... 6
5 Test Methods... 7
Appendix A (Normative) Test Methods of Brightness Response Characteristic 9
Appendix B (Normative) Test Methods of Signal-to-Noise Ratio... 14
Appendix C (Normative) Test Methods of Spatial Frequency Response... 18
Appendix D (Normative) Test Methods of Static Image Latitude... 24
Foreword
This Standard was drafted as per the rules specified in GB/T 1.1-2009.
Please note some contents of this document may involve patents. The issuing agency
of this document does not assume the responsibility to identify these patents.
This Standard was proposed by China Food and Drug Administration.
This Standard shall be under the jurisdiction of National Medical Optical and Instrument
Standardization Subcommittee (SAC/TC 103/SC1).
Drafting organizations of this Standard. Zhejiang Institute for the Control of Medical
Device; and National Institutes for Food and Drug Control.
Chief drafting staffs of this Standard. Yan Qinglai, Jia Xiaohang, Luo Yongjie, Shen
Huanbo, Zhang Qinyuan, Chen Debao, Liu Yanzhen, Su Zongwen, and Zheng Jian.
Medical Endoscopes - Endoscope Supply Units -
Video Camera System
1 Scope
This Standard specifies the terms, definitions, requirements, and test methods for
medical endoscopic camera system.
This Standard is applicable to medical endoscopic camera system (hereinafter referred
to as camera system) that are used as endoscope supply units in endoscopy and
surgery.
This Standard is not applicable to the camera system with special spectral effects and
non-visible spectral imaging.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) are applicable to this document.
GB 9706.19 Medical Electrical Equipment - Part 2.Particular Requirements for the
Safety of Endoscopic Equipment
3 Terms and Definitions
For the purpose of this document, the following terms and definitions apply.
3.1 Conversion function
3.2 Noise
The disturbances that are generated internally in the response signal of the camera
system.
3.3 Signal-to-noise ratio; SNR
At a specific signal level, the ratio of the output signal to the root mean square (rms) of
the noise signal, which is expressed by a logarithmic value. The expression is shown
in Formula (1).
3.4 Saturated value
The constant output signal value that is maintained to further increase the brightness
of the object surface.
3.5 Static image latitude
The ratio of the maximum critical object surface brightness to the minimum critical
object surface brightness that may be distinguished in a single exposure of the camera
system.
3.6 Spatial frequency response; SFR
In the camera system, the functional relationship BETWEEN target spatial frequency
AND the ratio of the modulation degree of the output signal calculated by the OECF
inverse function to the modulation degree of the target object surface brightness.
3.7 Sine-based spatial frequency response; s-SFR
SFR when the target is a sine wave modulation diagram.
3.8 Modulation degree
The ratio BETWEEN the maximum signal value minus the minimum signal value AND
the maximum signal value plus the minimum signal value.
3.9 Spectral neutrality
The reflection or transmission characteristics that is maintained constant against a
certain wavelength of light.
4 requirements
4.1 Requirements for detachable lens
4.1.1 Modulation transfer function (MTF)
The manufacturer shall give the nominal value of the spatial frequency corresponding
to the MTF value of the detachable lens at 50% in the attached information, the
tolerance is -20%, and the upper limit is not counted.
4.2 Brightness response characteristics
The manufacturer shall provide the output brightness electro-optical conversion
function or data list of the adapted monitor expressed in relative value in the technical
data. The sampling points of the data list are no less than 10, and cover the entire
latitude area.
4.3 Signal-to-noise ratio
The manufacturer shall provide the nominal value of the random noise signal-to-noise
ratio of the camera system and the corresponding camera mode (if the camera system
has multiple camera modes) in the technical data.
The tolerance of the signal-to-noise ratio is -20%, and the upper limit is not counted.
4.4 Spatial frequency response
The manufacturer shall provide, under the corresponding measurement conditions of
the camera system, the nominal value of the corresponding spatial frequency with the
SFR value of 50% and 30% in the attached information.
4.5 Static image latitude
The manufacturer shall provide the nominal value of the static image latitude and
corresponding camera mode (if the camera system has multiple camera modes) of the
camera system in the attached information.
The tolerance of static image latitude is -20%, and the upper limit is not counted.
4.6 Electrical safety
It shall meet the requirements of GB 9706.19.
5 Test Methods
5.1 Requirements for detachable lens
5.1.1 Modulation transfer function (MTF)
Place a ��10mm aperture in the measuring optical path, then measure by a general-
purpose device with sufficient accuracy.
5.1.2 Focal length
Place a ��10mm aperture in the measuring optical path, then measure by a focal length
meter with sufficient accuracy.
5.2 Test methods of brightness response characteristic
Check the content of the technical data provided by the manufacturer.
5.3 Test methods of signal-to-noise ratio
Check the content of the technical data provided by the manufacturer.
Measure the signal-to-noise ratio of the camera system according to the methods
specified in Appendix B.
5.4 Test methods of spatial frequency response
Check the contents of the attached information provided by the manufacturer.
Measure the spatial frequency response of the camera system according to the
methods specified in Appendix C.
5.5 Test methods of static image latitude
Check the contents of the attached information provided by the manufacturer.
Measure the static image latitude of the camera system according to the methods
specified in Appendix D.
5.6 Electrical safety
It shall be carried out in accordance with the test method specified in GB 9706.19.
Appendix A
(Normative)
Test Methods of Brightness Response Characteristic
A.1 Device
A.1.1 Test target board
As shown in Figure A.1, the test target board is composed of a background B that can
fill the entire field of view and a small gray scale block A.
Figure A.1 �C Test Target Board of Brightness Response Characteristic
Background B is a spectrum neutral gray scale board.
The small gray scale block A is an illuminating body whose brightness may be changed
independently. The brightness change range of the illuminating body shall be sufficient
to cover the tolerance of static image latitude for the tested camera system; and its
minimum brightness shall be much lower than the dark zone cut-off critical brightness
value of the tested camera system. The area and position of the gray scale block A
shall be set to ensure that the overall gain of the tested camera system including the
electronic shutter is not changed during the brightness adjustment process.
A.1.2 Light source
As shown in Figure A.2, both the illumination source B of the background B and the
illumination source A of the small gray-scale block A use the light source that simulates
the D65 standard illuminator. The simulation proximity shall ensure that the spectral
distribution curve of the light source is similar in shape with that of the simulated
standard illuminator; and the color temperature tolerance is ��10%. If it is claimed in the
Background B
instruction manual that the camera system is suitable for the illumination of a certain
type of light source, then the test light source shall use this type of light source or
simulate this type of illumination source.
The spatial uniformity of the background B illumination shall not exceed 20%; and the
spatial uniformity of the small gray-scale block A illumination shall not exceed 5%. The
time fluctuation of brightness should not exceed (where SNRtemp is
the random signal-to-noise ratio of the camera system under test).
A.2.2.3 Focus
If the camera system has an autofocus function, the focus can be slightly blurred when
shooting the test target board to reduce the noise generated by the texture of the block
itself. The emphasis here is "slightly", and the boundaries between blocks shall be
clearly distinguished.
A.2.2.4 Set the brightness of background B on the test target board
Adjust the brightness of background B on the test target board to achieve the
brightness value specified by the manufacturer. During the entire brightness
adjustment process of small grays-sale block A, the brightness of background B shall
keep the overall gain of the tested camera system unchanged.
A.2.2.5 Adjust the brightness of small gray scale block A on the test target board,
collect and analyze images
Gradually change the brightness of the small gray scale block A on the test target board,
and select no less than 10 different brightness levels that are basically uniformly
distributed within the latitude range. Corresponding to each brightness level, measure
the brightness value, record it as Li; and use the camera system to shoot the test target;
use the image collector to collect and save n images, n is no less than 8.
For the collected images, select (M �� N) pixels (32 �� 32 is recommended) in the area
of the small gray-scale block A; and respectively read the output signals of the output
signal (M �� N �� 3) matrix corresponding to the red, green, and blue channels in each
image.
Appendix B
(Normative)
Test Methods of Signal-to-Noise Ratio
B.1 Device
B.1.1 Test target board
The same as A.1.1.
B.1.2 Light source
The same as A.1.2.
B.1.3 Image collector
The same as A.1.4.
B.2 Procedure
B.2.1 Test conditions
The same as A.2.1.
B.2.2 Test process
B.2.2.1 White balance
The same as A.2.2.1.
B.2.2.2 Viewfinder of camera system
The same as A.2.2.2.
B.2.2.3 Focus
The same as A.2.2.3.
B.2.2.4 Set the brightness of background B on the test target board
The same as A.2.2.4.
B.2.2.5 Change the brightness of small gray scale block A on the test target
board, collect and analyze images
Gradually change the brightness of the small gray scale block A on the test target board;
and select no less than 10 different brightness levels that are basically uniformly
distributed within the latitude range. Corresponding to each brightness level, the
camera system shoots the test target; uses the image collector to collect n images and
save them; n is no less than 8.
For the collected images, select (M �� N) pixels (32 �� 32 is recommended) in the area
of the small gray-scale block A; and respectively read the output signals of the output
signal (M �� N �� 3) matrix corresponding to the red, green, and blue channels in each
image.
B.2.2.6 Calculate the luminance signal component according to the output signal
value of each channel of red, green and blue
For a certain brightness level, the average brightness signal component is
calculated by the arithmetic average of the Y values of (M �� N �� n) pixels; and Y is
obtained by weighting the output signals of the red, green and blue channels. The
weighted value of each channel is selected according to the encoding method given
by the manufacturer.
NOTE. The conventional standard codes can be found in ISO 22028-1.2004.
Example. If the encoding method adopts the encoding method specified in ITU-R
BT.709, the Y value calculation may be weighted as follows.
Where.
R, G, B �C output signal value of each channel of red, green and blue.
B.2.2.7 Calculation of noise (expressed in standard deviation)
According to the Value-Y obtained in B.2.2.6, calculate the output signal values of the
color difference channels (R-Y) and (B-Y).
The noise may be calculated according to Formula (B.2) as per the standard deviation
of the brightness component ��(Y), the standard deviations of the color difference
channels ��(R-Y) and ��(B-Y).
Where.
��(Y) �C standard deviation of the brightness signal component Y;
��(R-Y) �C standard deviation of brightness channel with red missing;
��(B-Y) �C standard deviation of brightness channel with blue missing.
The calculation of standard deviation in the Formula (B.2) shall follow the following
process.
For the coordinates (i, j) of any position in the area of M �� N, let Pk(i, j) be the signal
output value of the kth image at the coordinate position (i, j), and calculate the average
value of signal output of n images at this coordinate position according to Formula
(B.3).
According to Formula (B.4), calculate the standard deviation of the signal output of n
images at this coordinate position and record it as ��(i,j).
According to Formula (B.5), calculate the average value of the random noise in the
area of M��N, and record it as ��temp.
B.2.2.8 Calculate the signal-to-noise ratio of different brightness levels (different
gray scales), and draw the signal-to-noise ratio curve
According to the brightness signal components of different brightness levels
(different gray scales) captured by the camera system and noise values, calculate the
random noise signal-to-noise ratio of different brightness levels (different gray scales);
and draw the corresponding signal-to-noise ratio curve. The ordinate is the signal-to-
noise ratio, and the abscissa is the Value- of the brightness signal component.
B.2.2.9 Determine the signal-to-noise ratio of the camera system
Find the normalized signal-to-noise ratio with the brightness signal component
value of 0.707 from the signal-to-noise ratio curve. If 0.707 is not completely equal to
the output signal value corresponding to a certain gray scale, it is recommended to use
piecewise linear interpolation calculation to obtain the estimated value of the signal-to-
noise ratio.
B.3 Presentation of results
The test report shall include the following information.
a) The model and number of the camera system under test;
b) Lens condition, including model, focal length, and/or zoom condition of variable
magnification lens;
NOTE. The model of the non-detachable lens is often the same as the model of the
camera system itself.
c) Camera mode;
NOTE. It is applicable to camera systems that may adopt multiple camera modes.
d) The characteristics of the used light source;
e) The brightness L0 of background B on the test target board;
f) Measurement working distance d0;
g) Signal-to-noise ratio line graph;
h) Signal-to-noise ratio value.
Appendix C
(Normative)
Test Methods of Spatial Frequency Response
C.1 Device
C.1.1 Test target board
Sinewave star-shaped test target board. The target board shall be spectrally neutral;
and the background transmittance (reflection) rate is 18%. The star map shall be a
starlight pattern modulated by a sinewave; and the frequency is usually 144 cycles per
circle, as shown in Figure C.1.For endoscope system with a lower resolution, a 72-
period star or a fewer period star may be used.
The modulation degree of the test target board is known and is no less than 96%. The
target board has at least 32 black equal division lines in the radial direction.
Figure C.1 �C Sinewave Test Target Board
Other sinewave test target board with the equivalent effect may also be used.
C.1.2 Light source
Use a light source that simulates the D65 standard illuminator; and the simulation
proximity shall make the shape of the spectral distribution curve of the light source be
similar to that of the simulated standard illuminator; and the color temperature
tolerance is ��10%.
The arrangement of the illuminance source shall make the illumination uniform in the
area of the target board; and the difference between the brightness at any position in
the area and the center brightness shall be within ��10%.
C.1.3 Image collector
The same as A.1.4.
C.2 Procedures
C.2.1 Measurement conditions
C.2.1.1 Illumination conditions of the measurement target board
The brightness of the measurement target board shall enable the camera system to
produce acceptable output signal levels, but not overexposed.
C.2.2 Test process
C.2.2.1 White balance
The same as A.2.2.1.
C.2.2.2 Viewfinder of camera system
Adjust the shooting distance to the desired position, record it as the measurement
working distance d0, and center the test target board. For a camera system suitable
for visual observation endoscopes, d0 is 500mm; and other d0 is the design working
distance. For zoomable lenses, measure at the minimum focal length.
C.2.2.3 Camera system focus
If the camera system has auto-focus function, the auto-focus system of the camera
system shall be used to focus at the measurement working distance d0.If it is manual
focus, select the sharpest focus setting when the spatial frequency is about 1/4 of the
Nyquist frequency of the camera system.
C.2.2.4 Camera system settings
The image compression function of the camera system may significantly affect the
resolution measurement. Some camera systems may select whether to enable the
image compression function by pressing the button. All setting values of the camera
system may affect the measurement results, including the shooting mode, test distance,
etc., which shall be reported together with the measurement results.
C.2.2.5 Capture image
The camera system shoots the test target board; and uses the image collector to
collect and save the image.
C.2.2.6 Determine the Nyquist frequency
If the number of horizontal pixels is n, the Nyquist frequency is n/2 (LP/PH).
C.2.3 Results processing
The star map is divided into 24 parts. On each determined radius value, search for the
pixel closest to the radius; store the digital value and the angle (find the pixel under
this angle). If there are no pixels in the exact place, use the pixel value closest to the
radius position instead of using interpolation (see Figure C.2). This makes the error in
the result smaller than that in the pixel value interpolation method. Calculate the
average value of data of 3 parts, and finally get data of 8 parts.
Figure C.2 �C Radius Division of Star Map
The procedures used in the analysis are described in details below.
Procedure 1.Select the area to be analyzed that contains the entire star map.
Procedure 2.Perform star map segmentation selected by the user.
Procedure 3.Determine the pixel position along the radius (see Figure C.3); select the
digital code value (see Figure C.4); and record. According to the relative function of
the brightness electro-optical characteristics specified by the manufacturer (the inverse
function of OECF) or data list, calculate the output brightness value.
Procedure 4.Repeat Procedure 3 to analyze at least 32 radii.
Figure C.3 �C Pixel Position along Special Radius
Figure C.4 �C Digital Code Value according to Angle Condition
The intensity of harmonic Siemens star map is as follows.
Where. is initial phase; �� is baseline value of sinewave; b is amplitude of sinewave;
g is the number of pixels per cycle.
Use the following formula to calculate the angle of each pixel.
Where. x=0 and y=0 is regarded as the center of the star map. Since the initial phase
is uncertain, the following formula shall replace Formula (C.1).
Thereof,
Procedure 5.Determine the fitted sine curve according to the least square method.
Procedure 6.Calculate the modulation degree from the Formula (C.5), so that further
determine the modulation degree of the sine curve.
Figure C.5 �C Contrast Calculation of Sine Curve
Procedure 7.Obtain the functional relationship between the modulation degree in each
direction and the spatial frequency, and record it as SFR.
Procedure 8.Calculate the average value of SFR in each direction.
Procedure 9.Take LP/PH (line pair/image height) as the abscissa for the average value
of the SFR on the selected radii; and perform piecewise linear fitting to obtain the
frequency values with SFR values at 50% and 30%.
Procedure 10.Convert the frequency values when the SFR values are 50% and 30%
into the angular frequency of the corresponding object space.
NOTE. Due to the high contrast of the target board, the modulation degree of the target board
may be treated as 1.
If other equivalent sine wave test target boards are used, the result processing shall
refer to the above method equivalently.
C.3 Presentation of results
The test report shall include the following information.
a) The model and number of the camera system under test;
b) Camera mode;
NOTE. It is applicable to camera systems that may adopt multiple camera modes.
c) The characteristics of the used light source;
d) All setting values that may affect the measurement results, such as sharpness
settings (if any), lens conditions (including model, focal length, and/or zoom
status of variable magnification lenses), set the number of pixels or compression
mode, etc.
NOTE. The model of the non-detachable lens is often the same as the model of the
camera system itself.
e) Measurement working distance d0;
f) The number of cycles per circle of the star map; if the test board is not in the form
of a star map, declare the characteristics of the test board;
g) The angular frequency values of the corresponding object space when SFR is
30% and 50%, respectively;
h) Response curve of spatial frequency response (SFR).
Appendix D
(Normative)
Test Methods of Static Image Latitude
D.1 Device
D.1.1 Test target board
The same as A.1.1.
D.1.2 Light source
The same as A.1.2.
D.1.3 Brightness meter
The same as A.1.3.
D.1.4 Image collector
The same as A.1.4.
D.2 Procedures
D.2.1 Test conditions
The same as A.2.1.
D.2.2 Test process
D.2.2.1 White balance
The same as A.2.2.1.
D.2.2.2 Viewfinder of camera system
The same as A.2.2.2.
D.2.2.3 Focus
The same as A.2.2.3.
D.2.2.4 Set the brightness of background B on the test target board
The same as A.2.2.4.
D.2.2.5 Change the brightness of small gray scale block A on the test target
board, collect and analyze images
The brightness level change range of the small gray scale block A on the test target
board shall exceed the latitude range; and at least 5 brightness levels shall be lower
than the cut-off critical brightness value of the dark area of the camera system under
test. Near the cut-off critical brightness in the dark and light areas, the ratio of adjacent
brightness levels shall be no greater than 1.1 times.
Gradually change the brightness of the small gray scale block A on the test target board.
For each selected brightness level, measure and record the brightness value as Li; use
the camera system to shoot the test target board of the corresponding brightness; use
the image collector to collect n images and save, n is no less than 8.
For the collected images, select (M �� N) pixels (32 �� 32 is recommended) in the area
of the small gray-scale block A; and respectively read the output signals of the output
signal (M �� N �� 3) matrix corresponding to red, green, and blue channels in each image.
D.2.2.6 Calculate the brightness signal component according to the output
signal values of each channel of red, green and blue
The same as B.2.2.6.
D.2.2.7 Draw the curve of brightness and its corresponding brightness signal
output value
According to the Li and i obtained in procedures D.2.2.5 and D.2.2.6, draw the curve
of brightness and its corresponding brightness signal component.
D.2.2.8 Read the brightness saturation critical value of the highlighted area Lsat
Read the critical brightness value Lsat when the brightness signal component i of the
highlighted area on the curve is close to the saturation value.
NOTE. When any channel reaches saturation, it is saturated.
D.2.2.9 Calculate the cut-off critical value of brightness of the dark area Lmin
Read the critical brightness value Lmin when the brightness signal component i in the
dark area on the curve starts to cut off.
Judgment of cut-off state. TAKE the 2 times of average value of random noise that is
calculated according to B.2.2.7 plus average value of brightness signal component i
corresponding to the 5 groups of lower brightness levels obtained in D.2.2.5 AS the
threshold value. Find the data whose brightness output signal value is greater than the
threshold value and closest to the threshold value; the brightness corresponding to the
data is the critical brightness value Lmin.
D.2.2.10 Calculate the static image latitude
The latitude DR is determined according to Formula (D.1).
Where.
Lsat �C saturated critical value;
Lmin �C cut-off critical value.
D.3 Presentation of results
The test report shall include the following information.
a) The model and number of the camera system under test;
b) Lens condition, including model, focal length, and/or zoom condition of variable
magnification lens;
NOTE. The model of the non-detachable lens is often the same as the model of the
camera system itself.
c) Camera mode;
NOTE. It is applicable to camera systems that may adopt multiple camera modes.
d) The characteristics of the used light source;
e) The brightness L0 of background B on the test target board;
f) Measurement working distance d0;
g) Saturated critical value Lsat and cut-off critical value Lmin;
h) Static image latitude.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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