CaptureResult

Whether black-level compensation is locked to its current values, or is free to vary.

Whether the black level offset was locked for this frame. Should be ON if android.blackLevel.lock was ON in the capture request, unless a change in other capture settings forced the camera device to perform a black level reset.

Gains applying to Bayer raw color channels for white-balance.

These per-channel gains are either set by the camera device when the request android.colorCorrection.mode is not TRANSFORM_MATRIX, or directly by the application in the request when the android.colorCorrection.mode is TRANSFORM_MATRIX.

The gains in the result metadata are the gains actually applied by the camera device to the current frame.

The mode control selects how the image data is converted from the sensor's native color into linear sRGB color.

When auto-white balance (AWB) is enabled with android.control.awbMode, this control is overridden by the AWB routine. When AWB is disabled, the application controls how the color mapping is performed.

We define the expected processing pipeline below. For consistency across devices, this is always the case with TRANSFORM_MATRIX.

When either FULL or HIGH_QUALITY is used, the camera device may do additional processing but android.colorCorrection.gains and android.colorCorrection.transform will still be provided by the camera device (in the results) and be roughly correct.

Switching to TRANSFORM_MATRIX and using the data provided from FAST or HIGH_QUALITY will yield a picture with the same white point as what was produced by the camera device in the earlier frame.

The expected processing pipeline is as follows:

The white balance is encoded by two values, a 4-channel white-balance gain vector (applied in the Bayer domain), and a 3x3 color transform matrix (applied after demosaic).

The 4-channel white-balance gains are defined as:

android.colorCorrection.gains = [ R G_even G_odd B ]
 

where G_even is the gain for green pixels on even rows of the output, and G_odd is the gain for green pixels on the odd rows. These may be identical for a given camera device implementation; if the camera device does not support a separate gain for even/odd green channels, it will use the G_even value, and write G_odd equal to G_even in the output result metadata.

The matrices for color transforms are defined as a 9-entry vector:

android.colorCorrection.transform = [ I0 I1 I2 I3 I4 I5 I6 I7 I8 ]
 

which define a transform from input sensor colors, P_in = [ r g b ], to output linear sRGB, P_out = [ r' g' b' ],

with colors as follows:

r' = I0r + I1g + I2b
 g' = I3r + I4g + I5b
 b' = I6r + I7g + I8b
 

Both the input and output value ranges must match. Overflow/underflow values are clipped to fit within the range.

A color transform matrix to use to transform from sensor RGB color space to output linear sRGB color space.

This matrix is either set by the camera device when the request android.colorCorrection.mode is not TRANSFORM_MATRIX, or directly by the application in the request when the android.colorCorrection.mode is TRANSFORM_MATRIX.

In the latter case, the camera device may round the matrix to account for precision issues; the final rounded matrix should be reported back in this matrix result metadata. The transform should keep the magnitude of the output color values within [0, 1.0] (assuming input color values is within the normalized range [0, 1.0]), or clipping may occur.

The desired setting for the camera device's auto-exposure algorithm's antibanding compensation.

Some kinds of lighting fixtures, such as some fluorescent lights, flicker at the rate of the power supply frequency (60Hz or 50Hz, depending on country). While this is typically not noticeable to a person, it can be visible to a camera device. If a camera sets its exposure time to the wrong value, the flicker may become visible in the viewfinder as flicker or in a final captured image, as a set of variable-brightness bands across the image.

Therefore, the auto-exposure routines of camera devices include antibanding routines that ensure that the chosen exposure value will not cause such banding. The choice of exposure time depends on the rate of flicker, which the camera device can detect automatically, or the expected rate can be selected by the application using this control.

A given camera device may not support all of the possible options for the antibanding mode. The android.control.aeAvailableAntibandingModes key contains the available modes for a given camera device.

The default mode is AUTO, which must be supported by all camera devices.

If manual exposure control is enabled (by setting android.control.aeMode or android.control.mode to OFF), then this setting has no effect, and the application must ensure it selects exposure times that do not cause banding issues. The android.statistics.sceneFlicker key can assist the application in this.

Adjustment to auto-exposure (AE) target image brightness.

The adjustment is measured as a count of steps, with the step size defined by android.control.aeCompensationStep and the allowed range by android.control.aeCompensationRange.

For example, if the exposure value (EV) step is 0.333, '6' will mean an exposure compensation of +2 EV; -3 will mean an exposure compensation of -1 EV. One EV represents a doubling of image brightness. Note that this control will only be effective if android.control.aeMode != OFF. This control will take effect even when android.control.aeLock == true.

In the event of exposure compensation value being changed, camera device may take several frames to reach the newly requested exposure target. During that time, android.control.aeState field will be in the SEARCHING state. Once the new exposure target is reached, android.control.aeState will change from SEARCHING to either CONVERGED, LOCKED (if AE lock is enabled), or FLASH_REQUIRED (if the scene is too dark for still capture).

Whether auto-exposure (AE) is currently locked to its latest calculated values.

Note that even when AE is locked, the flash may be fired if the android.control.aeMode is ON_AUTO_FLASH / ON_ALWAYS_FLASH / ON_AUTO_FLASH_REDEYE.

When android.control.aeExposureCompensation is changed, even if the AE lock is ON, the camera device will still adjust its exposure value.

If AE precapture is triggered (see android.control.aePrecaptureTrigger) when AE is already locked, the camera device will not change the exposure time (android.sensor.exposureTime) and sensitivity (android.sensor.sensitivity) parameters. The flash may be fired if the android.control.aeMode is ON_AUTO_FLASH/ON_AUTO_FLASH_REDEYE and the scene is too dark. If the android.control.aeMode is ON_ALWAYS_FLASH, the scene may become overexposed.

See android.control.aeState for AE lock related state transition details.

The desired mode for the camera device's auto-exposure routine.

This control is only effective if android.control.mode is AUTO.

When set to any of the ON modes, the camera device's auto-exposure routine is enabled, overriding the application's selected exposure time, sensor sensitivity, and frame duration (android.sensor.exposureTime, android.sensor.sensitivity, and android.sensor.frameDuration). If one of the FLASH modes is selected, the camera device's flash unit controls are also overridden.

The FLASH modes are only available if the camera device has a flash unit (android.flash.info.available is true).

If flash TORCH mode is desired, this field must be set to ON or OFF, and android.flash.mode set to TORCH.

When set to any of the ON modes, the values chosen by the camera device auto-exposure routine for the overridden fields for a given capture will be available in its CaptureResult.

Whether the camera device will trigger a precapture metering sequence when it processes this request.

This entry is normally set to IDLE, or is not included at all in the request settings. When included and set to START, the camera device will trigger the autoexposure precapture metering sequence.

The precapture sequence should triggered before starting a high-quality still capture for final metering decisions to be made, and for firing pre-capture flash pulses to estimate scene brightness and required final capture flash power, when the flash is enabled.

Normally, this entry should be set to START for only a single request, and the application should wait until the sequence completes before starting a new one.

The exact effect of auto-exposure (AE) precapture trigger depends on the current AE mode and state; see android.control.aeState for AE precapture state transition details.

List of areas to use for metering.

The coordinate system is based on the active pixel array, with (0,0) being the top-left pixel in the active pixel array, and (android.sensor.info.activeArraySize.width - 1, android.sensor.info.activeArraySize.height - 1) being the bottom-right pixel in the active pixel array.

The weight must range from 0 to 1000, and represents a weight for every pixel in the area. This means that a large metering area with the same weight as a smaller area will have more effect in the metering result. Metering areas can partially overlap and the camera device will add the weights in the overlap region.

If all regions have 0 weight, then no specific metering area needs to be used by the camera device. If the metering region is outside the used android.scaler.cropRegion returned in capture result metadata, the camera device will ignore the sections outside the region and output the used sections in the result metadata.

Current state of the auto-exposure (AE) algorithm.

Switching between or enabling AE modes (android.control.aeMode) always resets the AE state to INACTIVE. Similarly, switching between android.control.mode, or android.control.sceneMode if android.control.mode == USE_SCENE_MODE resets all the algorithm states to INACTIVE.

The camera device can do several state transitions between two results, if it is allowed by the state transition table. For example: INACTIVE may never actually be seen in a result.

The state in the result is the state for this image (in sync with this image): if AE state becomes CONVERGED, then the image data associated with this result should be good to use.

Below are state transition tables for different AE modes.

When android.control.aeMode is AE_MODE_ON_*:

For the above table, the camera device may skip reporting any state changes that happen without application intervention (i.e. mode switch, trigger, locking). Any state that can be skipped in that manner is called a transient state.

For example, for above AE modes (AE_MODE_ON_*), in addition to the state transitions listed in above table, it is also legal for the camera device to skip one or more transient states between two results. See below table for examples:

Range over which fps can be adjusted to maintain exposure.

Only constrains auto-exposure (AE) algorithm, not manual control of android.sensor.exposureTime

Whether auto-focus (AF) is currently enabled, and what mode it is set to.

Only effective if android.control.mode = AUTO and the lens is not fixed focus (i.e. android.lens.info.minimumFocusDistance > 0).

If the lens is controlled by the camera device auto-focus algorithm, the camera device will report the current AF status in android.control.afState in result metadata.

List of areas to use for focus estimation.

The coordinate system is based on the active pixel array, with (0,0) being the top-left pixel in the active pixel array, and (android.sensor.info.activeArraySize.width - 1, android.sensor.info.activeArraySize.height - 1) being the bottom-right pixel in the active pixel array.

The weight must range from 0 to 1000, and represents a weight for every pixel in the area. This means that a large metering area with the same weight as a smaller area will have more effect in the metering result. Metering areas can partially overlap and the camera device will add the weights in the overlap region.

If all regions have 0 weight, then no specific metering area needs to be used by the camera device. If the metering region is outside the used android.scaler.cropRegion returned in capture result metadata, the camera device will ignore the sections outside the region and output the used sections in the result metadata.

Current state of auto-focus (AF) algorithm.

Switching between or enabling AF modes (android.control.afMode) always resets the AF state to INACTIVE. Similarly, switching between android.control.mode, or android.control.sceneMode if android.control.mode == USE_SCENE_MODE resets all the algorithm states to INACTIVE.

The camera device can do several state transitions between two results, if it is allowed by the state transition table. For example: INACTIVE may never actually be seen in a result.

The state in the result is the state for this image (in sync with this image): if AF state becomes FOCUSED, then the image data associated with this result should be sharp.

Below are state transition tables for different AF modes.

When android.control.afMode is AF_MODE_OFF or AF_MODE_EDOF:

When android.control.afMode is AF_MODE_AUTO or AF_MODE_MACRO:

For the above table, the camera device may skip reporting any state changes that happen without application intervention (i.e. mode switch, trigger, locking). Any state that can be skipped in that manner is called a transient state.

For example, for these AF modes (AF_MODE_AUTO and AF_MODE_MACRO), in addition to the state transitions listed in above table, it is also legal for the camera device to skip one or more transient states between two results. See below table for examples:

When android.control.afMode is AF_MODE_CONTINUOUS_VIDEO:

When android.control.afMode is AF_MODE_CONTINUOUS_PICTURE:

When switch between AF_MODE_CONTINUOUS_* (CAF modes) and AF_MODE_AUTO/AF_MODE_MACRO (AUTO modes), the initial INACTIVE or PASSIVE_SCAN states may be skipped by the camera device. When a trigger is included in a mode switch request, the trigger will be evaluated in the context of the new mode in the request. See below table for examples:

Whether the camera device will trigger autofocus for this request.

This entry is normally set to IDLE, or is not included at all in the request settings.

When included and set to START, the camera device will trigger the autofocus algorithm. If autofocus is disabled, this trigger has no effect.

When set to CANCEL, the camera device will cancel any active trigger, and return to its initial AF state.

Generally, applications should set this entry to START or CANCEL for only a single capture, and then return it to IDLE (or not set at all). Specifying START for multiple captures in a row means restarting the AF operation over and over again.

See android.control.afState for what the trigger means for each AF mode.

Whether auto-white balance (AWB) is currently locked to its latest calculated values.

Note that AWB lock is only meaningful when android.control.awbMode is in the AUTO mode; in other modes, AWB is already fixed to a specific setting.

Whether auto-white balance (AWB) is currently setting the color transform fields, and what its illumination target is.

This control is only effective if android.control.mode is AUTO.

When set to the ON mode, the camera device's auto-white balance routine is enabled, overriding the application's selected android.colorCorrection.transform, android.colorCorrection.gains and android.colorCorrection.mode.

When set to the OFF mode, the camera device's auto-white balance routine is disabled. The application manually controls the white balance by android.colorCorrection.transform, android.colorCorrection.gains and android.colorCorrection.mode.

When set to any other modes, the camera device's auto-white balance routine is disabled. The camera device uses each particular illumination target for white balance adjustment. The application's values for android.colorCorrection.transform, android.colorCorrection.gains and android.colorCorrection.mode are ignored.

List of areas to use for illuminant estimation.

The coordinate system is based on the active pixel array, with (0,0) being the top-left pixel in the active pixel array, and (android.sensor.info.activeArraySize.width - 1, android.sensor.info.activeArraySize.height - 1) being the bottom-right pixel in the active pixel array.

The weight must range from 0 to 1000, and represents a weight for every pixel in the area. This means that a large metering area with the same weight as a smaller area will have more effect in the metering result. Metering areas can partially overlap and the camera device will add the weights in the overlap region.

If all regions have 0 weight, then no specific metering area needs to be used by the camera device. If the metering region is outside the used android.scaler.cropRegion returned in capture result metadata, the camera device will ignore the sections outside the region and output the used sections in the result metadata.

Current state of auto-white balance (AWB) algorithm.

Switching between or enabling AWB modes (android.control.awbMode) always resets the AWB state to INACTIVE. Similarly, switching between android.control.mode, or android.control.sceneMode if android.control.mode == USE_SCENE_MODE resets all the algorithm states to INACTIVE.

The camera device can do several state transitions between two results, if it is allowed by the state transition table. So INACTIVE may never actually be seen in a result.

The state in the result is the state for this image (in sync with this image): if AWB state becomes CONVERGED, then the image data associated with this result should be good to use.

Below are state transition tables for different AWB modes.

When android.control.awbMode != AWB_MODE_AUTO:

When android.control.awbMode is AWB_MODE_AUTO:

For the above table, the camera device may skip reporting any state changes that happen without application intervention (i.e. mode switch, trigger, locking). Any state that can be skipped in that manner is called a transient state.

For example, for this AWB mode (AWB_MODE_AUTO), in addition to the state transitions listed in above table, it is also legal for the camera device to skip one or more transient states between two results. See below table for examples:

Information to the camera device 3A (auto-exposure, auto-focus, auto-white balance) routines about the purpose of this capture, to help the camera device to decide optimal 3A strategy.

This control (except for MANUAL) is only effective if android.control.mode != OFF and any 3A routine is active.

ZERO_SHUTTER_LAG will be supported if android.request.availableCapabilities contains ZSL. MANUAL will be supported if android.request.availableCapabilities contains MANUAL_SENSOR.

A special color effect to apply.

When this mode is set, a color effect will be applied to images produced by the camera device. The interpretation and implementation of these color effects is left to the implementor of the camera device, and should not be depended on to be consistent (or present) across all devices.

A color effect will only be applied if android.control.mode != OFF.

Overall mode of 3A control routines.

High-level 3A control. When set to OFF, all 3A control by the camera device is disabled. The application must set the fields for capture parameters itself.

When set to AUTO, the individual algorithm controls in android.control.* are in effect, such as android.control.afMode.

When set to USE_SCENE_MODE, the individual controls in android.control.* are mostly disabled, and the camera device implements one of the scene mode settings (such as ACTION, SUNSET, or PARTY) as it wishes. The camera device scene mode 3A settings are provided by android.control.sceneModeOverrides.

When set to OFF_KEEP_STATE, it is similar to OFF mode, the only difference is that this frame will not be used by camera device background 3A statistics update, as if this frame is never captured. This mode can be used in the scenario where the application doesn't want a 3A manual control capture to affect the subsequent auto 3A capture results.

A camera mode optimized for conditions typical in a particular capture setting.

This is the mode that that is active when android.control.mode == USE_SCENE_MODE. Aside from FACE_PRIORITY, these modes will disable android.control.aeMode, android.control.awbMode, and android.control.afMode while in use. The scene modes available for a given camera device are listed in android.control.availableSceneModes.

The interpretation and implementation of these scene modes is left to the implementor of the camera device. Their behavior will not be consistent across all devices, and any given device may only implement a subset of these modes.

Whether video stabilization is active.

Video stabilization automatically translates and scales images from the camera in order to stabilize motion between consecutive frames.

If enabled, video stabilization can modify the android.scaler.cropRegion to keep the video stream stabilized

Operation mode for edge enhancement.

Edge/sharpness/detail enhancement. OFF means no enhancement will be applied by the camera device.

This must be set to one of the modes listed in android.edge.availableEdgeModes.

FAST/HIGH_QUALITY both mean camera device determined enhancement will be applied. HIGH_QUALITY mode indicates that the camera device will use the highest-quality enhancement algorithms, even if it slows down capture rate. FAST means the camera device will not slow down capture rate when applying edge enhancement.

The desired mode for for the camera device's flash control.

This control is only effective when flash unit is available (android.flash.info.available == true).

When this control is used, the android.control.aeMode must be set to ON or OFF. Otherwise, the camera device auto-exposure related flash control (ON_AUTO_FLASH, ON_ALWAYS_FLASH, or ON_AUTO_FLASH_REDEYE) will override this control.

When set to OFF, the camera device will not fire flash for this capture.

When set to SINGLE, the camera device will fire flash regardless of the camera device's auto-exposure routine's result. When used in still capture case, this control should be used along with auto-exposure (AE) precapture metering sequence (android.control.aePrecaptureTrigger), otherwise, the image may be incorrectly exposed.

When set to TORCH, the flash will be on continuously. This mode can be used for use cases such as preview, auto-focus assist, still capture, or video recording.

The flash status will be reported by android.flash.state in the capture result metadata.

Current state of the flash unit.

When the camera device doesn't have flash unit (i.e. android.flash.info.available == false), this state will always be UNAVAILABLE. Other states indicate the current flash status.

Set operational mode for hot pixel correction.

Valid modes for this camera device are listed in android.hotPixel.availableHotPixelModes.

Hotpixel correction interpolates out, or otherwise removes, pixels that do not accurately encode the incoming light (i.e. pixels that are stuck at an arbitrary value).

A location object to use when generating image GPS metadata.

Orientation of JPEG image to write

Compression quality of the final JPEG image.

85-95 is typical usage range.

Compression quality of JPEG thumbnail.

Resolution of embedded JPEG thumbnail.

When set to (0, 0) value, the JPEG EXIF will not contain thumbnail, but the captured JPEG will still be a valid image.

When a jpeg image capture is issued, the thumbnail size selected should have the same aspect ratio as the jpeg image.

If the thumbnail image aspect ratio differs from the JPEG primary image aspect ratio, the camera device creates the thumbnail by cropping it from the primary image. For example, if the primary image has 4:3 aspect ratio, the thumbnail image has 16:9 aspect ratio, the primary image will be cropped vertically (letterbox) to generate the thumbnail image. The thumbnail image will always have a smaller Field Of View (FOV) than the primary image when aspect ratios differ.

The ratio of lens focal length to the effective aperture diameter.

This will only be supported on the camera devices that have variable aperture lens. The aperture value can only be one of the values listed in android.lens.info.availableApertures.

When this is supported and android.control.aeMode is OFF, this can be set along with android.sensor.exposureTime, android.sensor.sensitivity, and android.sensor.frameDuration to achieve manual exposure control.

The requested aperture value may take several frames to reach the requested value; the camera device will report the current (intermediate) aperture size in capture result metadata while the aperture is changing. While the aperture is still changing, android.lens.state will be set to MOVING.

When this is supported and android.control.aeMode is one of the ON modes, this will be overridden by the camera device auto-exposure algorithm, the overridden values are then provided back to the user in the corresponding result.

State of lens neutral density filter(s).

This will not be supported on most camera devices. On devices where this is supported, this may only be set to one of the values included in android.lens.info.availableFilterDensities.

Lens filters are typically used to lower the amount of light the sensor is exposed to (measured in steps of EV). As used here, an EV step is the standard logarithmic representation, which are non-negative, and inversely proportional to the amount of light hitting the sensor. For example, setting this to 0 would result in no reduction of the incoming light, and setting this to 2 would mean that the filter is set to reduce incoming light by two stops (allowing 1/4 of the prior amount of light to the sensor).

It may take several frames before the lens filter density changes to the requested value. While the filter density is still changing, android.lens.state will be set to MOVING.

The current lens focal length; used for optical zoom.

This setting controls the physical focal length of the camera device's lens. Changing the focal length changes the field of view of the camera device, and is usually used for optical zoom.

Like android.lens.focusDistance and android.lens.aperture, this setting won't be applied instantaneously, and it may take several frames before the lens can change to the requested focal length. While the focal length is still changing, android.lens.state will be set to MOVING.

This is expected not to be supported on most devices.

Distance to plane of sharpest focus, measured from frontmost surface of the lens.

Should be zero for fixed-focus cameras

The range of scene distances that are in sharp focus (depth of field).

If variable focus not supported, can still report fixed depth of field range

Sets whether the camera device uses optical image stabilization (OIS) when capturing images.

OIS is used to compensate for motion blur due to small movements of the camera during capture. Unlike digital image stabilization (android.control.videoStabilizationMode), OIS makes use of mechanical elements to stabilize the camera sensor, and thus allows for longer exposure times before camera shake becomes apparent.

Not all devices will support OIS; see android.lens.info.availableOpticalStabilization for available controls.

Current lens status.

For lens parameters android.lens.focalLength, android.lens.focusDistance, android.lens.filterDensity and android.lens.aperture, when changes are requested, they may take several frames to reach the requested values. This state indicates the current status of the lens parameters.

When the state is STATIONARY, the lens parameters are not changing. This could be either because the parameters are all fixed, or because the lens has had enough time to reach the most recently-requested values. If all these lens parameters are not changable for a camera device, as listed below:

• Fixed focus (android.lens.info.minimumFocusDistance == 0), which means android.lens.focusDistance parameter will always be 0.
• Fixed focal length (android.lens.info.availableFocalLengths contains single value), which means the optical zoom is not supported.
• No ND filter (android.lens.info.availableFilterDensities contains only 0).
• Fixed aperture (android.lens.info.availableApertures contains single value).

Then this state will always be STATIONARY.

When the state is MOVING, it indicates that at least one of the lens parameters is changing.

Mode of operation for the noise reduction algorithm.

Noise filtering control. OFF means no noise reduction will be applied by the camera device.

This must be set to a valid mode from android.noiseReduction.availableNoiseReductionModes.

FAST/HIGH_QUALITY both mean camera device determined noise filtering will be applied. HIGH_QUALITY mode indicates that the camera device will use the highest-quality noise filtering algorithms, even if it slows down capture rate. FAST means the camera device will not slow down capture rate when applying noise filtering.

A frame counter set by the framework. This value monotonically increases with every new result (that is, each new result has a unique frameCount value).

Reset on release()

Specifies the number of pipeline stages the frame went through from when it was exposed to when the final completed result was available to the framework.

Depending on what settings are used in the request, and what streams are configured, the data may undergo less processing, and some pipeline stages skipped.

See android.request.pipelineMaxDepth for more details.

The region of the sensor to read out for this capture.

The crop region coordinate system is based off android.sensor.info.activeArraySize, with (0, 0) being the top-left corner of the sensor active array.

Output streams use this rectangle to produce their output, cropping to a smaller region if necessary to maintain the stream's aspect ratio, then scaling the sensor input to match the output's configured resolution.

The crop region is applied after the RAW to other color space (e.g. YUV) conversion. Since raw streams (e.g. RAW16) don't have the conversion stage, they are not croppable. The crop region will be ignored by raw streams.

For non-raw streams, any additional per-stream cropping will be done to maximize the final pixel area of the stream.

For example, if the crop region is set to a 4:3 aspect ratio, then 4:3 streams will use the exact crop region. 16:9 streams will further crop vertically (letterbox).

Conversely, if the crop region is set to a 16:9, then 4:3 outputs will crop horizontally (pillarbox), and 16:9 streams will match exactly. These additional crops will be centered within the crop region.

The width and height of the crop region cannot be set to be smaller than floor( activeArraySize.width / android.scaler.availableMaxDigitalZoom ) and floor( activeArraySize.height / android.scaler.availableMaxDigitalZoom ), respectively.

The camera device may adjust the crop region to account for rounding and other hardware requirements; the final crop region used will be included in the output capture result.

Duration each pixel is exposed to light.

If the sensor can't expose this exact duration, it should shorten the duration exposed to the nearest possible value (rather than expose longer).

Duration from start of frame exposure to start of next frame exposure.

The maximum frame rate that can be supported by a camera subsystem is a function of many factors:

• Requested resolutions of output image streams
• Availability of binning / skipping modes on the imager
• The bandwidth of the imager interface
• The bandwidth of the various ISP processing blocks

Since these factors can vary greatly between different ISPs and sensors, the camera abstraction tries to represent the bandwidth restrictions with as simple a model as possible.

The model presented has the following characteristics:

• The image sensor is always configured to output the smallest resolution possible given the application's requested output stream sizes. The smallest resolution is defined as being at least as large as the largest requested output stream size; the camera pipeline must never digitally upsample sensor data when the crop region covers the whole sensor. In general, this means that if only small output stream resolutions are configured, the sensor can provide a higher frame rate.
• Since any request may use any or all the currently configured output streams, the sensor and ISP must be configured to support scaling a single capture to all the streams at the same time. This means the camera pipeline must be ready to produce the largest requested output size without any delay. Therefore, the overall frame rate of a given configured stream set is governed only by the largest requested stream resolution.
• Using more than one output stream in a request does not affect the frame duration.
• Certain format-streams may need to do additional background processing before data is consumed/produced by that stream. These processors can run concurrently to the rest of the camera pipeline, but cannot process more than 1 capture at a time.

The necessary information for the application, given the model above, is provided via the android.scaler.streamConfigurationMap field using StreamConfigurationMap#getOutputMinFrameDuration(int, Size). These are used to determine the maximum frame rate / minimum frame duration that is possible for a given stream configuration.

Specifically, the application can use the following rules to determine the minimum frame duration it can request from the camera device:

1. Let the set of currently configured input/output streams be called S.
2. Find the minimum frame durations for each stream in S, by looking it up in android.scaler.streamConfigurationMap using StreamConfigurationMap#getOutputMinFrameDuration(int, Size) (with its respective size/format). Let this set of frame durations be called F.
3. For any given request R, the minimum frame duration allowed for R is the maximum out of all values in F. Let the streams used in R be called S_r.

If none of the streams in S_r have a stall time (listed in StreamConfigurationMap#getOutputStallDuration(int,Size) using its respective size/format), then the frame duration in F determines the steady state frame rate that the application will get if it uses R as a repeating request. Let this special kind of request be called Rsimple.

A repeating request Rsimple can be occasionally interleaved by a single capture of a new request Rstall (which has at least one in-use stream with a non-0 stall time) and if Rstall has the same minimum frame duration this will not cause a frame rate loss if all buffers from the previous Rstall have already been delivered.

For more details about stalling, see StreamConfigurationMap#getOutputStallDuration(int,Size).

The worst-case divergence between Bayer green channels.

This value is an estimate of the worst case split between the Bayer green channels in the red and blue rows in the sensor color filter array.

The green split is calculated as follows:

1. A 5x5 pixel (or larger) window W within the active sensor array is chosen. The term 'pixel' here is taken to mean a group of 4 Bayer mosaic channels (R, Gr, Gb, B). The location and size of the window chosen is implementation defined, and should be chosen to provide a green split estimate that is both representative of the entire image for this camera sensor, and can be calculated quickly.
2. The arithmetic mean of the green channels from the red rows (mean_Gr) within W is computed.
3. The arithmetic mean of the green channels from the blue rows (mean_Gb) within W is computed.
4. The maximum ratio R of the two means is computed as follows: R = max((mean_Gr + 1)/(mean_Gb + 1), (mean_Gb + 1)/(mean_Gr + 1))

The ratio R is the green split divergence reported for this property, which represents how much the green channels differ in the mosaic pattern. This value is typically used to determine the treatment of the green mosaic channels when demosaicing.

The green split value can be roughly interpreted as follows:

• R < 1.03 is a negligible split (<3% divergence).
• 1.20 <= R >= 1.03 will require some software correction to avoid demosaic errors (3-20% divergence).
• R > 1.20 will require strong software correction to produce a usuable image (>20% divergence).

Optional - This value may be null on some devices.

The estimated camera neutral color in the native sensor colorspace at the time of capture.

This value gives the neutral color point encoded as an RGB value in the native sensor color space. The neutral color point indicates the currently estimated white point of the scene illumination. It can be used to interpolate between the provided color transforms when processing raw sensor data.

The order of the values is R, G, B; where R is in the lowest index.

Optional - This value may be null on some devices.

The amount of gain applied to sensor data before processing.

The sensitivity is the standard ISO sensitivity value, as defined in ISO 12232:2006.

The sensitivity must be within android.sensor.info.sensitivityRange, and if if it less than android.sensor.maxAnalogSensitivity, the camera device is guaranteed to use only analog amplification for applying the gain.

If the camera device cannot apply the exact sensitivity requested, it will reduce the gain to the nearest supported value. The final sensitivity used will be available in the output capture result.

A pixel [R, G_even, G_odd, B] that supplies the test pattern when android.sensor.testPatternMode is SOLID_COLOR.

Each color channel is treated as an unsigned 32-bit integer. The camera device then uses the most significant X bits that correspond to how many bits are in its Bayer raw sensor output.

For example, a sensor with RAW10 Bayer output would use the 10 most significant bits from each color channel.

Optional - This value may be null on some devices.

When enabled, the sensor sends a test pattern instead of doing a real exposure from the camera.

When a test pattern is enabled, all manual sensor controls specified by android.sensor.* will be ignored. All other controls should work as normal.

For example, if manual flash is enabled, flash firing should still occur (and that the test pattern remain unmodified, since the flash would not actually affect it).

Optional - This value may be null on some devices.

Time at start of exposure of first row of the image sensor, in nanoseconds.

The timestamps are also included in all image buffers produced for the same capture, and will be identical on all the outputs. The timestamps measure time since an unspecified starting point, and are monotonically increasing.

They can be compared with the timestamps for other captures from the same camera device, but are not guaranteed to be comparable to any other time source.

Quality of lens shading correction applied to the image data.

When set to OFF mode, no lens shading correction will be applied by the camera device, and an identity lens shading map data will be provided if android.statistics.lensShadingMapMode == ON. For example, for lens shading map with size specified as android.lens.info.shadingMapSize = [ 4, 3 ], the output android.statistics.lensShadingMap for this case will be an identity map shown below:

[ 1.0, 1.0, 1.0, 1.0,  1.0, 1.0, 1.0, 1.0,
 1.0, 1.0, 1.0, 1.0,  1.0, 1.0, 1.0, 1.0,
 1.0, 1.0, 1.0, 1.0,  1.0, 1.0, 1.0, 1.0,
 1.0, 1.0, 1.0, 1.0,  1.0, 1.0, 1.0, 1.0,
 1.0, 1.0, 1.0, 1.0,   1.0, 1.0, 1.0, 1.0,
 1.0, 1.0, 1.0, 1.0,  1.0, 1.0, 1.0, 1.0 ]
 

When set to other modes, lens shading correction will be applied by the camera device. Applications can request lens shading map data by setting android.statistics.lensShadingMapMode to ON, and then the camera device will provide lens shading map data in android.statistics.lensShadingMap, with size specified by android.lens.info.shadingMapSize; the returned shading map data will be the one applied by the camera device for this capture request.

The shading map data may depend on the auto-exposure (AE) and AWB statistics, therefore the reliability of the map data may be affected by the AE and AWB algorithms. When AE and AWB are in AUTO modes(android.control.aeMode != OFF and android.control.awbMode != OFF), to get best results, it is recommended that the applications wait for the AE and AWB to be converged before using the returned shading map data.

List of the faces detected through camera face detection in this result.

Only available if android.statistics.faceDetectMode != OFF.

Control for the face detector unit.

Whether face detection is enabled, and whether it should output just the basic fields or the full set of fields. Value must be one of the android.statistics.info.availableFaceDetectModes.

List of (x, y) coordinates of hot/defective pixels on the sensor.

A coordinate (x, y) must lie between (0, 0), and (width - 1, height - 1) (inclusive), which are the top-left and bottom-right of the pixel array, respectively. The width and height dimensions are given in android.sensor.info.pixelArraySize. This may include hot pixels that lie outside of the active array bounds given by android.sensor.info.activeArraySize.

Operating mode for hotpixel map generation.

If set to ON, a hotpixel map is returned in android.statistics.hotPixelMap. If set to OFF, no hotpixel map will be returned.

This must be set to a valid mode from android.statistics.info.availableHotPixelMapModes.

The shading map is a low-resolution floating-point map that lists the coefficients used to correct for vignetting, for each Bayer color channel.

The least shaded section of the image should have a gain factor of 1; all other sections should have gains above 1.

When android.colorCorrection.mode = TRANSFORM_MATRIX, the map must take into account the colorCorrection settings.

The shading map is for the entire active pixel array, and is not affected by the crop region specified in the request. Each shading map entry is the value of the shading compensation map over a specific pixel on the sensor. Specifically, with a (N x M) resolution shading map, and an active pixel array size (W x H), shading map entry (x,y) ϵ (0 ... N-1, 0 ... M-1) is the value of the shading map at pixel ( ((W-1)/(N-1)) * x, ((H-1)/(M-1)) * y) for the four color channels. The map is assumed to be bilinearly interpolated between the sample points.

The channel order is [R, Geven, Godd, B], where Geven is the green channel for the even rows of a Bayer pattern, and Godd is the odd rows. The shading map is stored in a fully interleaved format.

The shading map should have on the order of 30-40 rows and columns, and must be smaller than 64x64.

As an example, given a very small map defined as:

width,height = [ 4, 3 ]
 values =
 [ 1.3, 1.2, 1.15, 1.2,  1.2, 1.2, 1.15, 1.2,
 1.1, 1.2, 1.2, 1.2,  1.3, 1.2, 1.3, 1.3,
 1.2, 1.2, 1.25, 1.1,  1.1, 1.1, 1.1, 1.0,
 1.0, 1.0, 1.0, 1.0,  1.2, 1.3, 1.25, 1.2,
 1.3, 1.2, 1.2, 1.3,   1.2, 1.15, 1.1, 1.2,
 1.2, 1.1, 1.0, 1.2,  1.3, 1.15, 1.2, 1.3 ]
 

The low-resolution scaling map images for each channel are (displayed using nearest-neighbor interpolation):

As a visualization only, inverting the full-color map to recover an image of a gray wall (using bicubic interpolation for visual quality) as captured by the sensor gives:

Whether the camera device will output the lens shading map in output result metadata.

When set to ON, android.statistics.lensShadingMap will be provided in the output result metadata.

The camera device estimated scene illumination lighting frequency.

Many light sources, such as most fluorescent lights, flicker at a rate that depends on the local utility power standards. This flicker must be accounted for by auto-exposure routines to avoid artifacts in captured images. The camera device uses this entry to tell the application what the scene illuminant frequency is.

When manual exposure control is enabled (android.control.aeMode == OFF or android.control.mode == OFF), the android.control.aeAntibandingMode doesn't perform antibanding, and the application can ensure it selects exposure times that do not cause banding issues by looking into this metadata field. See android.control.aeAntibandingMode for more details.

Reports NONE if there doesn't appear to be flickering illumination.

Tonemapping / contrast / gamma curve to use when android.tonemap.mode is CONTRAST_CURVE.

The tonemapCurve consist of three curves for each of red, green, and blue channels respectively. The following example uses the red channel as an example. The same logic applies to green and blue channel. Each channel's curve is defined by an array of control points:

curveRed =
 [ P0(in, out), P1(in, out), P2(in, out), P3(in, out), ..., PN(in, out) ]
 2 <= N <= android.tonemap.maxCurvePoints

These are sorted in order of increasing Pin; it is always guaranteed that input values 0.0 and 1.0 are included in the list to define a complete mapping. For input values between control points, the camera device must linearly interpolate between the control points.

Each curve can have an independent number of points, and the number of points can be less than max (that is, the request doesn't have to always provide a curve with number of points equivalent to android.tonemap.maxCurvePoints).

A few examples, and their corresponding graphical mappings; these only specify the red channel and the precision is limited to 4 digits, for conciseness.

Linear mapping:

curveRed = [ (0, 0), (1.0, 1.0) ]
 

Invert mapping:

curveRed = [ (0, 1.0), (1.0, 0) ]
 

Gamma 1/2.2 mapping, with 16 control points:

curveRed = [
 (0.0000, 0.0000), (0.0667, 0.2920), (0.1333, 0.4002), (0.2000, 0.4812),
 (0.2667, 0.5484), (0.3333, 0.6069), (0.4000, 0.6594), (0.4667, 0.7072),
 (0.5333, 0.7515), (0.6000, 0.7928), (0.6667, 0.8317), (0.7333, 0.8685),
 (0.8000, 0.9035), (0.8667, 0.9370), (0.9333, 0.9691), (1.0000, 1.0000) ]
 

Standard sRGB gamma mapping, per IEC 61966-2-1:1999, with 16 control points:

curveRed = [
 (0.0000, 0.0000), (0.0667, 0.2864), (0.1333, 0.4007), (0.2000, 0.4845),
 (0.2667, 0.5532), (0.3333, 0.6125), (0.4000, 0.6652), (0.4667, 0.7130),
 (0.5333, 0.7569), (0.6000, 0.7977), (0.6667, 0.8360), (0.7333, 0.8721),
 (0.8000, 0.9063), (0.8667, 0.9389), (0.9333, 0.9701), (1.0000, 1.0000) ]
 

High-level global contrast/gamma/tonemapping control.

When switching to an application-defined contrast curve by setting android.tonemap.mode to CONTRAST_CURVE, the curve is defined per-channel with a set of (in, out) points that specify the mapping from input high-bit-depth pixel value to the output low-bit-depth value. Since the actual pixel ranges of both input and output may change depending on the camera pipeline, the values are specified by normalized floating-point numbers.

More-complex color mapping operations such as 3D color look-up tables, selective chroma enhancement, or other non-linear color transforms will be disabled when android.tonemap.mode is CONTRAST_CURVE.

This must be set to a valid mode in android.tonemap.availableToneMapModes.

When using either FAST or HIGH_QUALITY, the camera device will emit its own tonemap curve in android.tonemap.curve. These values are always available, and as close as possible to the actually used nonlinear/nonglobal transforms.

If a request is sent with CONTRAST_CURVE with the camera device's provided curve in FAST or HIGH_QUALITY, the image's tonemap will be roughly the same.

Get a capture result field value.

The field definitions can be found in CaptureResult.

Querying the value for the same key more than once will return a value which is equal to the previous queried value.

Get the frame number associated with this result.

Whenever a request has been processed, regardless of failure or success, it gets a unique frame number assigned to its future result/failure.

This value monotonically increments, starting with 0, for every new result or failure; and the scope is the lifetime of the CameraDevice.

Returns a list of the keys contained in this map.

The list returned is not modifiable, so any attempts to modify it will throw a UnsupportedOperationException.

All values retrieved by a key from this list with #get are guaranteed to be non-null. Each key is only listed once in the list. The order of the keys is undefined.

Get the request associated with this result.

Whenever a request has been fully or partially captured, with onCaptureCompleted(CameraDevice, CaptureRequest, TotalCaptureResult) or onCaptureProgressed(CameraDevice, CaptureRequest, CaptureResult), the result's getRequest() will return that request.

For example,

cameraDevice.capture(someRequest, new CaptureListener() {
     @Override
     void onCaptureCompleted(CaptureRequest myRequest, CaptureResult myResult) {
         assert(myResult.getRequest.equals(myRequest) == true);
     }
 }, null);
 

The sequence ID for this failure that was returned by the capture(CaptureRequest, CameraDevice.CaptureListener, Handler) family of functions.

The sequence ID is a unique monotonically increasing value starting from 0, incremented every time a new group of requests is submitted to the CameraDevice.