1、 IEEE Standard for Camera Phone Image Quality Sponsored by the Corporate Advisory Board IEEE 3 Park Avenue New York, NY 10016-5997 USA IEEE Standards Association Board of Governors IEEE Std 1858-2016 (Incorporates IEEE Std 1858-2016/Cor 1-2017) IEEE Std 1858-2016 (Incorporating IEEE Std 1858-2016/Co
2、r 1-2017) IEEE Standard for Camera Phone Image Quality Sponsor Corporate Advisory Group of the IEEE Standards Association Board of Governors Approved 22 September 2016 IEEE-SA Standards Board ii Abstract: Quantifying the performance of camera-equipped mobile devices is covered in this standard, with
3、 an emphasis on metrics and procedures appropriate to the types of sensors, lenses, and signal processing routines present on such devices. It is not intended as a general image quality standard for photographs produced by high-end dedicated cameras, e.g., DSLRs. Metrics include spatial frequency re
4、sponse, color uniformity, chroma level, lateral chromatic displacement, local geometric distortion, texture blur, and visual noise. Keywords: camera, cell phone, IEEE 1858, image quality, mobile, photography, visual quality The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, N
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34、rticipants At the time this IEEE standard was completed, the Camera Phone Image Quality Working Group had the following membership: Margaret Belska, Chair Leland Yu, Vice Chair Apkudo Inc. AT one for cameras with VGA sensor size (640480 pixels) and one for higher pixel-count cameras. The test charts
35、 are shown in Figure 5 and Figure 6. For purposes of illustration, these figures also contain markers (green and red squares) for the regions of interest (ROI) used for the SFR measurements together with their corresponding field positions. These markers are not part of the printed test chart. 1:1 1
36、:11:1 1:14:3 4:34:3 4:30%0%0% 0% 30%T30%T30%T30%T60%T60%T60%T60%T60%T60%T60%T60%T60%S60%S60%S60%S60%S60%S60%S60%S30%S30%S30%S30%S75%T75%T 75%T75%T75%S75%S75%S75%SFigure 5 Test target format for VGA cameras. The red and green squares indicate the ROI, each either sagittal (S) or tangential (T), for t
37、he SFR measurements and are not part of the chart. IEEE Std 1858-2016 IEEE Standard for Camera Phone Image Quality 12 Copyright 2017 IEEE. All rights reserved. 1:1 1:11:1 1:14:3 4:34:3 4:33:2 3:23:2 3:216:9 16:916:9 16:90%0%0%0%25%S25%S25%S25%S50%S75%S50%S75%S50%S75%S 50%S75%S75%S50%S50%S75%S50%S75%
38、S75%S75%S75%S50%S25%T 25%T75%T50%T50%T25%T50%T25%T75%T 50%T 75%T50%T75%T75%T75%T50%T75%T50%T75%T75%T75%T50%TFigure 6 Test target format for cameras with higher pixel counts than VGA. The red and green squares indicate the ROI for the SFR measurements and are not part of the chart. All field position
39、s are related to the diagonal of the 4:3 target aspect ratio. The targets contain different features whose characteristics and application are as follows: There should be features aiding in framing the image. These features could be framing arrows, or as illustrated in Figure 5 and Figure 6, crosses
40、 where appropriate framing is obtained if one quarter of each of the four crosses for a particular format are visible in the image. The mean reflectance or transmittance of the active area (i.e., the area containing the squares) shall be between 0.15 and 0.25. The recommended target width size is 20
41、 in to 40 in. All slanted-edge squares shall have a size and edge ROI that is sufficiently large to satisfy the 32 32 pixels sample requirement of ISO 12233:2014. The edge shall have a modulation contrast between 0.55 and 0.65 with a mean level of between 0.12 and 0.25 reflectance. Table 1 below pro
42、vides a number of possible minimum/maximum density pairs that satisfy this criterion based on the following equations: maxmin2avgmod max minlog10 10 10Contrast modulationDDDC DD The minimum frequency content of the edge features is further specified in Table 2. This table describes the minimum spati
43、al frequency (cy/mm) associated with the 80% SFR level of each specified target size and sensor size pair. Correction for this finite target SFR is required before reporting the camera SFR. Unless otherwise noted, a 5% positional tolerance relative to the nominal field position is allowed. Except fo
44、r the center squares, the slanted-edge squares may have a tilt of up to 10 relative to the polar coordinates if geometric distortion of the lens requires such accommodation. If this occurs, then all slanted-edge squares within the active area shall also have the same degree of relative tilt. The cen
45、ter slanted-edge squares shall be at a 5 tilt with a rotational tolerance of 2. They shall be centered within the active area. IEEE Std 1858-2016 IEEE Standard for Camera Phone Image Quality 13 Copyright 2017 IEEE. All rights reserved. For the large-sized test chart, there shall be slanted-edge squa
46、res used to measure SFR centered at multiples of 16.5% of the 4:3 aspect ratio image height in the radial direction from the edge of the nearest square closer to the center of the image. For the squares closest to the image center, the center should be located at 16.5% of the 4:3 image height relati
47、ve to the center of the image. The positions of the squares shall extend radially from the center of the chart in the 0, 45, 90, 135, and 180 directions. The sides of the squares shall be 15% of the 4:3 aspect ratio image height. Optionally, squares can also be placed at the 22.5 and 157.5 direction
48、s. There is no requirement to measure SFR at these positions, because this puts very high requirements on the printing device. For the VGA camera test chart, there shall be slanted-edge squares used to measure SFR centered at multiples of 21.5% of the 4:3 aspect ratio image height in the radial dire
49、ction from the edge of the nearest square closer to the center of the image. For the squares closest to the image center, the center should be located at 21.5% of the 4:3 image height relative to the center of the image. The positions of the squares shall extend radially from the center of the chart in the 0, 45, 90, 135, and 180 directions. The sides of the squares shall be 20% of the 4:3 aspect ratio image height. Optionally, squares can also be placed at the 22.5 and 157.5 directions. There is no requirement
