如何正确从rgb565转换为rgb888 [英] How to correctly convert from rgb565 to rgb888
问题描述
我试图将一个值从rgb565转换为rgb888,但我似乎不能得到它的权利。
我也检查了一些现有的答案,如这一个但有一些值似乎没有正确转换。
I'm trying to convert a value from rgb565 to rgb888 but I can't seem to get it right. I've also checked a few existing answers like this one but there are values that don't seem to be properly convert.
这里是我到目前为止尝试过的:
Here's what I've tried so far:
PImage picker;
int c;
void setup(){
size(285,240);
picker = loadImage("hsv.gif");
int c = color(255,255,255);
byte[] word = colorToWord(c);
int[] rgb = wordToRGB(word);
noStroke();
fill(c);
rect(0,0,50,100);
fill(rgb[0],rgb[1],rgb[2]);
rect(50,0,50,100);
}
void draw(){
image(picker,0,0);
if((mouseX >= 0 && mouseX <= picker.width)&&
(mouseY >= 0 && mouseY <= picker.height)) c = picker.get(mouseX,mouseY);
byte[] word = colorToWord(c);
int[] rgb = wordToRGB(word);
// int[] rgb = rgbWordToRGB(word);
int cc = color(rgb[0],rgb[1],rgb[2]);
fill(c);
rect(0,159,142,80);
fill(cc);
rect(142,159,143,80);
fill(0);
text("original\n"+hex(c),10,185);
text("converted\n"+hex(cc),152,185);
}
byte[] colorToWord(int c){
int r = (c >> 16) & 0xFF;
int g = (c >> 8) & 0xFF;
int b = c & 0xFF;
return new byte[]{(byte)((r&248)|g>>5),(byte)((g&28)<<3|b>>3)};
}
int[] wordToRGB3(byte[] data){
// Reconstruct 16 bit rgb565 value from two bytes
int rgb565 = (data[0] & 255) | ((data[1] & 255) << 8);
// Extract raw component values (range 0..31 for g and b, 0..63 for g)
int b5 = rgb565 & 0x1f;
int g6 = (rgb565 >> 5) & 0x3f;
int r5 = (rgb565 >> 11) & 0x1f;
// Scale components up to 8 bit:
// Shift left and fill empty bits at the end with the highest bits,
// so 00000 is extended to 000000000 but 11111 is extended to 11111111
int b = (b5 << 3) | (b5 >> 2);
int g = (g6 << 2) | (g6 >> 4);
int r = (r5 << 3) | (r5 >> 2);
return new int[]{r,g,b};
}
int[] wordToRGB2(byte[] word){
int r = word[0]&248;
int g = (word[0]<<5) | ((word[1]&28)>>3);
int b = word[1] << 3;
r <<= 3;
g <<= 2;
b <<= 3;
return new int[]{r,g,b};
}
int[] wordToRGB(byte[] word){
int c = (word[0] << 8) | (word[1]);
//RGB565
int r = (c >> (6+5)) & 0x01F;
int g = (c >> 5) & 0x03F;
int b = (c) & 0x01F;
//RGB888 - amplify
r <<= 3;
g <<= 2;
b <<= 3;
return new int[]{r,g,b};
}
final int RGB565_MASK_RED = 0xF800;
final int RGB565_MASK_GREEN = 0x07E0;
final int RGB565_MASK_BLUE = 0x001F;
int[] rgbWordToRGB(byte[] word){
int rgb565 = (word[0] << 8) | (word[1]);
int[] rgb24 = new int[3];
rgb24[2] = (rgb565 & RGB565_MASK_RED) >> 11;
rgb24[1] = (rgb565 & RGB565_MASK_GREEN) >> 5;
rgb24[0] = (rgb565 & RGB565_MASK_BLUE);
//amplify the image
rgb24[2] <<= 3;
rgb24[1] <<= 2;
rgb24[0] <<= 3;
return rgb24;
}
使用此图片作为调色板:
using this image as a colour palette:
问题在于某些值:
为什么会发生这种情况?有没有办法解决这个问题?
Why does that happen ? Is there a way to fix that ?
推荐答案
确定所以这里的修复如果我理解正确:
ok so here's the fix if I understand correctly:
替换第一行:
int c = (word[0] << 8) | (word[1]);
int c = (word[0] << 8) | (word[1] & 0xFF);
当从byte转换为int时,会出现问题。示例1:
The problem happens when you convert from byte to int. Example 1:
int a = 255;
println(binary(a));
int b = (byte) 255;
println(binary(b));
列印:
00000000000000000000000011111111
11111111111111111111111111111111
示例2:
int a = 127;
println(binary(a));
int b = (byte) 127;
println(binary(b));
列印:
00000000000000000000000001111111
00000000000000000000000001111111
位,所以基本上之后,你的扭曲所有的值。
Processing pads with to the left with whatever your last bit was, so essentially after that, your | distorts all the values.
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