i.MX ProcessorsのトピックIMX6 color key for 16 bit frame buffer

IMX6 color key for 16 bit frame buffer

richogrady — Tue, 26 Sep 2017 14:34:56 GMT

We are using frame buffers with 16 bit color (fb0 and fb1). If we choose a 16 bit color key how do we convert that to the 24 bit value that gets submitted via IOCTL MXCFB_SET_CLR_KEY?

Re: IMX6 color key for 16 bit frame buffer

richogrady — Wed, 27 Sep 2017 15:55:38 GMT

We did some head banging to figure this out. Wish it was documented somewhere, if it is please advise.

For a 16 bit RGB565 color:

red = ((color16 & 0xf800) >> 11) * 256 / 0x1f;

grn = ((color16 & 0x07e0) >> 5) * 256 / 0x3f;

blu = ((color16 & 0x0001f) >> 0) * 256 / 0x1f;

if(red > 0xff) red = 0xff;

if(grn > 0xff) grn = 0xff;

if(blu > 0xff) blu = 0xff;

color24 = (red << 16) + (grn << 8) + (blu << 0);

Not sure this is exactly how they implemented it, but it works.

Re: IMX6 color key for 16 bit frame buffer

art — Thu, 28 Sep 2017 11:55:22 GMT

There are various ways of mapping the 16-bit color value to 24-bit wide LCD bus,
and they may depend on the processor type. What exactly processor do you use?

Have a great day,
Artur