Contents

vImageConvert_ARGB8888toRGB565(_:_:_:)

Removes the alpha channel from an 8-bit-per-channel ARGB buffer to produce an RGB565 result.

Declaration

func vImageConvert_ARGB8888toRGB565(_ src: UnsafePointer<vImage_Buffer>, _ dest: UnsafePointer<vImage_Buffer>, _ flags: vImage_Flags) -> vImage_Error

Parameters

  • src:

    The source vImage buffer.

  • dest:

    A pointer to the destination vImage buffer structure. You’re responsible for filling out the Height, Width, and Rowbytes fields of this structure, and for allocating a data buffer of the appropriate size. On return, the data buffer this structure points to contains the destination image data. When you no longer need the data buffer, deallocate the memory to prevent memory leaks.

  • flags:

    The options to use when performing the operation. If your code implements its own tiling or its own multithreading, pass Kvimagedonottile; otherwise, pass Kvimagenoflags.

Return Value

kvImageNoError; otherwise, one of the error codes in Data Types and Constants.

Discussion

The function uses the following calculation to perform the conversion:

    uint32_t red   = (8bitRedChannel   * (31*2) + 255) / (255*2)
    uint32_t green = (8bitGreenChannel * 63 + 127) / 255
    uint32_t blue  = (8bitBlueChannel  * 31 + 127) / 255
    uint16_t RGB565pixel = (red << 11) | (green <<  5) | blue

See Also

Conversion from 8-bit-per-channel, 4-channel interleaved buffers