CGImage 是否支持每通道 16 位？

Question

bitsPerComponent表示最多为 8，但有几个 Stack Overflow 问题暗示支持16。

Answer 1

It seems that the official documentation is wrong

https://www.websupergoo.com/helppdfnet/default.htm?page=source%2F6-abcpdf.objects%2Fpixmap%2F2-properties%2Fbitspercomponent.htm Helps to confirm this

Answer 2

You can find the necessary information in “Supported Pixel Formats“ in the “Graphics Contexts“ chapter of “Quartz 2D Programming Guide“ below even it is archived documentation.

https://developer.apple.com/library/archive/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_context/dq_context.html

The below figure is taken from the above url.

Note that “bpp“ is specified as “bits per pixel“ and “bcp“ is “bits per component“. As given in above table, it seems that only Mac OS (>=10.X versions) supports 16 bcp, not iOS.