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Monochrome Cameras

Devices running Android 9 or higher can support monochrome cameras. Android 10 provides additional support for the Y8 stream format, monochrome and near-infrared (NIR) color filter array static metadata, and DngCreator functions for monochrome cameras.

With this capability, device manufacturers can implement a monochrome or NIR camera device and reduce memory use by using the Y8 stream format. A monochrome camera can serve as the underlying physical camera of a logical multi-camera device to achieve better low-light noise characteristics.

Implementation

Hardware requirements

To implement this feature, your device must have a monochrome camera sensor and an image signal processor (ISP) to process the sensor output.

Implementing a monochrome camera

To advertise a camera device as a monochrome camera, the Camera HAL must meet the following requirements:

  • android.sensor.info.colorFilterArray is set to MONO or NIR.
  • BACKWARD_COMPATIBLE required keys are supported and MANUAL_POST_PROCESSING isn't supported.
  • android.control.awbAvailableModes only contains AUTO and android.control.awbState is either CONVERTED or LOCKED depending on android.control.awbLock.
  • android.colorCorrection.mode, android.colorCorrection.transform, and android.colorCorrection.gains aren't in available request and result keys. As a result, the camera device is LIMITED.
  • The following color-related static metadata keys aren't present:

    • android.sensor.referenceIlluminant*
    • android.sensor.calibrationTransform*
    • android.sensor.colorTransform*
    • android.sensor.forwardMatrix*
    • android.sensor.neutralColorPoint
    • android.sensor.greenSplit
  • All color channels have the same values for the following metadata keys:

    • android.sensor.blackLevelPattern
    • android.sensor.dynamicBlackLevel
    • android.statistics.lensShadingMap
    • android.tonemap.curve
  • android.sensor.noiseProfile has only one color channel.

For monochrome devices supporting Y8 stream formats, the Camera HAL must support swapping YUV_420_888 formats in mandatory stream combinations (including reprocessing) with Y8 formats.

The following public APIs are used in this feature:

For more details on the Camera HAL, see docs.html. For more information on related public APIs, see ImageFormat, CameraCharacteristics, CaptureRequest, and CaptureResult.

Validation

To validate your implementation of a monochrome camera, run the following CTS and VTS tests.

CTS tests

  • testMonochromeCharacteristics
  • CaptureRequestTest
  • CaptureResultTest
  • StillCaptureTest
  • DngCreatorTest

VTS tests

  • getCameraCharacteristics
  • processMultiCaptureRequestPreview