Converts an RGBA8888 image into an RGBA5551 image.


func vImageConvert_RGBA8888toRGBA5551(_ src: UnsafePointer<vImage_Buffer>, _ dest: UnsafePointer<vImage_Buffer>, _ flags: vImage_Flags) -> vImage_Error



A pointer to a vImage buffer structure that contains the source image whose data you want to convert.


A pointer to a vImage buffer data 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, you must deallocate the memory.


The options to use when performing the operation. If you plan to perform your own tiling or use multithreading, pass kvImageDoNotTile.

Return Value

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


The RGBA5551 format has 16-bit pixels with 1 bit for alpha and 5 bits each for red, green, and blue. The function calculates the 16-bit pixels in the destination image as follows:

    uint32_t alpha = (8bitAlphaChannel      + 127) / 255
    uint32_t red   = (8bitRedChannel   * 31 + 127) / 255
    uint32_t green = (8bitGreenChannel * 31 + 127) / 255
    uint32_t blue  = (8bitBlueChannel  * 31 + 127) / 255
    uint16_t ARGB1555pixel = (alpha << 15) | (red <<  10) | (green << 5) | blue

See Also

Converting from RGBA Formats

func vImageConvert_RGBAFFFFtoRGBFFF(UnsafePointer<vImage_Buffer>!, UnsafePointer<vImage_Buffer>!, vImage_Flags) -> vImage_Error

Converts a four-channel RGBAFFFF image to a three-channel RGBFFF image by removing the alpha channel.

func vImageConvert_RGBA8888toRGB888(UnsafePointer<vImage_Buffer>, UnsafePointer<vImage_Buffer>, vImage_Flags) -> vImage_Error

Converts a four-channel RGBA8888 image to a three-channel RGB888 image by removing the alpha channel.