How to convert 32(24) bit color to 16 bit?

Question

So guys, I’m in big trouble rsrs, I’m creating an editing tool for a PS2 football game.

And this game has two "systems" of colors, which are they:

The "normal" RGB that is; R: 0 to 255, G: 0 to 255, B: 0 to 255.

And the, or think is rsrs 5bitRGB; R: 0 to 31, G: 0 to 31, B: 0 to 31.

And here’s the thing, the "normal" RGB I can send its value to the textbox. And after sending the value to the textbox, I save this value directly in the game file via Hex, thus changing to the color I want, until then beauty.

This works because... because the "slot" of bytes of this color in the game file are actually 3 bytes, so saving the value sent in Hex of the textbox works.

Except that now the problem is the 5bitRGB, the "slot" of it in the game file is only 2 bytes, not 3, and colorDialog the color options are "normal" from 0 to 255 both in R, G and B, there is no way to do only from 0 to 31, and the worst problem, how to send the value of colorDialog in this 5bitRGB format in 2 bytes to the textbox? rsrs will be possible?

Answer 1

Colors obtained in Colordialog are in RGB8888 format, where each color is represented by 8 bits plus 8 bits for alpha channel.

There are two 16-bit RGB formats, RGB555 and RGB565.

In the first, the colors are represented by 5 bits each, in the second, the colors RED and BLUE are represented with 5 bits and the color GREEN with 6.

As I do not know which format concerned, I leave two methods that convert RGB8888 to each of them.

RGB565:

public ushort Convert8888RGBto565RGB(Color color)
{
    //reduz para 5 bits significativos
    byte r = (byte) (color.R >> 3);
    //reduz para 6 bits significativos
    byte g = (byte)(color.G >> 2);
    //reduz para 5 bits significativos
    byte b = (byte)(color.B >> 3);

    //Junta
    return (ushort)((r << 11) | (g << 5) | b);
}

RGB555

public ushort Convert8888RGBto555RGB(Color color)
{
    //reduz para 5 bits significativos
    byte r = (byte)(color.R >> 3);
    //reduz para 5 bits significativos
    byte g = (byte)(color.G >> 3);
    //reduz para 5 bits significativos
    byte b = (byte)(color.B >> 3);

    //Junta
    return (ushort)((r << 10) | (g << 5) | b);
}

References:

• Working with 16-bit RGB.