vImageConvert_ARGB1555toARGB8888(_:_:_:)
Converts an ARGB1555 4-channel interleaved buffer to an 8-bit-per-channel, 4-channel interleaved buffer.
Declaration
func vImageConvert_ARGB1555toARGB8888(_ src: UnsafePointer<vImage_Buffer>, _ dest: UnsafePointer<vImage_Buffer>, _ flags: vImage_Flags) -> vImage_ErrorParameters
- 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 ARGB1555 format has 16-bit pixels with 1 bit for alpha and 5 bits each for red, green, and blue. The function uses the following calculation to perform the conversion:
destA->data[x] = 1bitAlphaChannel * 255;
destR->data[x] = (5bitRedChannel * 255 + 15) / 31;
destG->data[x] = (5bitGreenChannel * 255 + 15) / 31;
destB->data[x] = (5bitBlueChannel * 255 + 15) / 31;