AS0260CSSC28SUD20 datasheet(53/83 Pages) ONSEMI

53 / 83 page

AS0260 DS Rev. G Pub. 5/15 EN

©Semiconductor Components Industries, LLC, 2015.

AS0260: 1/6-Inch 1080P High-Definition (HD) System-On-A-Chip (SOC) Digi-

tal Image Sensor

Backlight Compensation

The backlight compensation control helps the AS0260 auto-exposure (AE) algorithm

correctly exposure the image for typical backlit scenes. The AS0260 has an AE 'window'

that controls which parts of the scene should be considered by the auto-exposure algo-

rithm. This window control is not part of the UVC interface (see CAM_STAT_AE_INI-

TIAL_WINDOW_xxx). The AS0260 divides the AE window into a grid of 5 x 5 'zones'.

Each zone has a weighting factor, which allows the host to prioritize the average bright-

ness of some zones more than others (when being considered by the AE algorithm).

• When backlight compensation is disabled, the AS0260 will apply the same weighting

to all zones - this is equivalent to taking the average brightness of the entire AE

window.

• When backlight compensation level 1 is enabled, the AS0260 will apply a 'backlight

compensation' map of weights to the zones, in order to prioritize the central zones

over outlying zones (on the assumption that the region-of-interest is within the centre

of the AE window). The zone weight map is static, configured by the AE_RULE_AE_-

WEIGHT_TABLE_N_M variables, and is not under UVC Control.

• When backlight compensation level 2 is enabled, the AS0260 employs an adaptive

algorithm, which uses the average brightness of each zone to determine the zone

weighting. Darker zones have more weighting. Level 2 uses medium strength adaptive

weighting, where the zone weighting applied is a 50/50 blend of the static and adap-

tive weighting.

• Backlight compensation level 3 is similar to level 2, except only the adaptive weighting

is applied to the zone weighting.

• Backlight compensation level 4 uses the static weight map as in level 1, but centres

the AE 'window' to the central 9 zones. The average brightness of the 16 outlier zones

is not calculated.

Changes to this control will be rejected with EACCES when auto-exposure mode is

disabled.

Brightness

The brightness control is used to set the desired brightness of the scene when auto-

exposure mode is enabled. When auto-exposure is disabled, any change will be rejected

with EACCES.

The brightness of a scene is measured by the average luma of the pixels enclosed by the

AE window The auto-exposure algorithm will attempt to keep the average luma of these

pixels at the desired brightness (within configurable thresholds for smoothing the adap-

tion rate).

Increasing the desired brightness of a scene may result in a change in frame-rate if

UVC_AE_PRIORITY_CONTROL is set to VARIABLE_FRAME_RATE. Conversely, reducing

the desired brightness may increase frame-rate.

Variable

Name

Type

Default

0xCC08

VAR(0x13,0x0008)

UVC_BACKLIGHT_COMPENSATION_CONTROL

UINT16 Dependent upon CAM

configuration

Variable

Name

Type

Default

R0xCC0A

VAR(0x13,0x000A)

UVC_BRIGHTNESS_CONTROL

UINT16

Dependent upon CAM

configuration

AS0260CSSC28SUD20 数据表(PDF) 53 Page - ON Semiconductor

AS0260CSSC28SUD20 数据表(HTML) 53 Page - ON Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83

数据表下载