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Add conversion for HSB to RGBW and back
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for KNX DPT251.600 to use all 4 colors.

With the new feature, the HSBType can converted into RGBW, and also back
to HSB.

Due to the conversion, some accuracy is lost, but the result is
approximately correct.

Signed-off-by: Marco Müller <[email protected]>
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@genesis81
marco authored and genesis81 committed Oct 17, 2023
1 parent 14f8490 commit 1bb3ef0
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101 changes: 100 additions & 1 deletion bundles/org.openhab.core/src/main/java/org/openhab/core/util/ColorUtil.java
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,10 @@ public class ColorUtil {
private static final BigDecimal BIG_DECIMAL_60 = BigDecimal.valueOf(60);
private static final BigDecimal BIG_DECIMAL_5 = BigDecimal.valueOf(5);
private static final BigDecimal BIG_DECIMAL_3 = BigDecimal.valueOf(3);
private static final BigDecimal BIG_DECIMAL_2 = BigDecimal.valueOf(2);
private static final BigDecimal BIG_DECIMAL_2_POINT_55 = new BigDecimal("2.55");
private static final BigDecimal BIG_DECIMAL_0 = BigDecimal.valueOf(0);
private static final BigDecimal BIG_DECIMAL_127_POINT_5 = BigDecimal.valueOf(127.5);

public static final Gamut DEFAULT_GAMUT = new Gamut(new double[] { 0.9961, 0.0001 }, new double[] { 0, 0.9961 },
new double[] { 0, 0.0001 });
Expand Down Expand Up @@ -79,7 +82,7 @@ public static int[] hsbToRgb(HSBType hsb) {
* This function does not round the components. For conversion to integer values in the range 0 to 255 use
* {@link #hsbToRgb(HSBType)}.
*
* See also: {@link #hsbToRgb(HSBType)}, {@link #hsbTosRgb(HSBType)}
* See also: {@link #hsbToRgb(HSBType)}, {@link #hsbTosRgb(HSBType)}, {@link #hsbToRgbwPercent(HSBType)}
*
* @param hsb an {@link HSBType} value.
* @return array of three {@link PercentType} with the RGB values in the range 0 to 100 percent.
Expand Down Expand Up @@ -140,6 +143,102 @@ public static PercentType[] hsbToRgbPercent(HSBType hsb) {
return new PercentType[] { red, green, blue };
}

/**
* Transform <a href="https://en.wikipedia.org/wiki/HSL_and_HSV">HSV</a> based {@link HSBType} to RGBW.
*
* See <a href=
* "https://stackoverflow.com/questions/40312216/converting-rgb-to-rgbw">Converting RGB to RGBW</a>.
*
* This function does not round the components. For conversion to integer values in the range 0 to 255 use
* {@link #hsbToRgb(HSBType)}.
*
* See also: {@link #hsbToRgb(HSBType)}, {@link #hsbTosRgb(HSBType)}, {@link #hsbToRgbPercent(HSBType)}
*
* @param hsb an {@link HSBType} value.
* @return array of four {@link PercentType} with the RGBW values in the range 0 to 100 percent.
*/
public static PercentType[] hsbToRgbwPercent(HSBType hsb) {
int[] rgb = hsbToRgb(hsb);
final BigDecimal Ri = new BigDecimal(rgb[0]);
final BigDecimal Gi = new BigDecimal(rgb[1]);
final BigDecimal Bi = new BigDecimal(rgb[2]);
// Get the maximum between R, G, and B
final BigDecimal tM = Ri.max(Gi.max(Bi));

// If the maximum value is 0, immediately return pure black.
if (tM.floatValue() == 0) {
return new PercentType[] { PercentType.ZERO, PercentType.ZERO, PercentType.ZERO, PercentType.ZERO };
}

// This section serves to figure out what the color with 100% hue is
final BigDecimal multiplier = BIG_DECIMAL_255.divide(tM, 0, RoundingMode.DOWN);
final BigDecimal hR = Ri.multiply(multiplier);
final BigDecimal hG = Gi.multiply(multiplier);
final BigDecimal hB = Bi.multiply(multiplier);

// This calculates the Whiteness (not strictly speaking Luminance) of the color
final BigDecimal M = hR.max(hG.max(hB));
final BigDecimal m = hR.min(hG.min(hB));
final BigDecimal Luminance = ((M.add(m).divide(BIG_DECIMAL_2).subtract(BIG_DECIMAL_127_POINT_5))
.multiply(BIG_DECIMAL_255.divide(BIG_DECIMAL_127_POINT_5))).divide(multiplier);

// Calculate the output values
BigDecimal Ro = (Ri.subtract(Luminance).multiply(BIG_DECIMAL_100).divide(BIG_DECIMAL_255, 0,
RoundingMode.DOWN));
BigDecimal Go = (Gi.subtract(Luminance).multiply(BIG_DECIMAL_100).divide(BIG_DECIMAL_255, 0,
RoundingMode.DOWN));
BigDecimal Bo = (Bi.subtract(Luminance).multiply(BIG_DECIMAL_100).divide(BIG_DECIMAL_255, 0,
RoundingMode.DOWN));
BigDecimal Wo = Luminance.multiply(BIG_DECIMAL_100).divide(BIG_DECIMAL_255, 0, RoundingMode.DOWN);

// check range
Ro = BIG_DECIMAL_100.min(Ro.max(BIG_DECIMAL_0));
Go = BIG_DECIMAL_100.min(Go.max(BIG_DECIMAL_0));
Bo = BIG_DECIMAL_100.min(Bo.max(BIG_DECIMAL_0));
Wo = BIG_DECIMAL_100.min(Wo.max(BIG_DECIMAL_0));

return new PercentType[] { new PercentType(Ro), new PercentType(Go), new PercentType(Bo), new PercentType(Wo) };
}

/**
* Transform <a href="https://en.wikipedia.org/wiki/HSL_and_HSV">HSV</a> based {@link HSBType} to RGBW.
*
* See <a href=
* "https://stackoverflow.com/questions/40312216/converting-rgb-to-rgbw">Converting RGB to RGBW</a>.
*
* This function does not round the components. For conversion to integer values in the range 0 to 255 use
* {@link #hsbToRgb(HSBType)}.
*
* See also: {@link #hsbToRgb(HSBType)}, {@link #hsbTosRgb(HSBType)}, {@link #hsbToRgbPercent(HSBType)}
*
* @param rgb array of three int with the RGB values in the range 0 to 255.
* @return hsb an {@link HSBType} value.
*
*/
public static HSBType rgbwTohsb(double r, double g, double b, double w) {

BigDecimal Luminance = BigDecimal.valueOf(w);
BigDecimal Ri = BigDecimal.valueOf(r).add(Luminance);
BigDecimal Gi = BigDecimal.valueOf(g).add(Luminance);
BigDecimal Bi = BigDecimal.valueOf(b).add(Luminance);

// Get the maximum between R, G, and B
final BigDecimal tM = BIG_DECIMAL_255.min(Ri.max(Gi.max(Bi)).max(BIG_DECIMAL_0));

// If the maximum value is 0, immediately return pure black.
if (tM.floatValue() == 0) {
return HSBType.BLACK;
}

final BigDecimal multiplier = BIG_DECIMAL_255.divide(tM, 0, RoundingMode.DOWN);

BigDecimal Ro = Ri.divide(multiplier).min(BIG_DECIMAL_255).max(BIG_DECIMAL_0);
BigDecimal Go = Gi.divide(multiplier).min(BIG_DECIMAL_255).max(BIG_DECIMAL_0);
BigDecimal Bo = Bi.divide(multiplier).min(BIG_DECIMAL_255).max(BIG_DECIMAL_0);

return HSBType.fromRGB(Ro.intValue(), Go.intValue(), Bo.intValue());
}

/**
* Transform <a href="https://en.wikipedia.org/wiki/HSL_and_HSV">HSV</a> based {@link HSBType}
* to the RGB value representing the color in the default
Expand Down
65 changes: 65 additions & 0 deletions bundles/org.openhab.core/src/test/java/org/openhab/core/util/ColorUtilTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,71 @@ public void inversionTest(HSBType hsb) {
assertThat(deltaBri, is(lessThanOrEqualTo(1.0)));
}

@Test
public void hsbtorgbwTest() {
HSBType hsb = HSBType.WHITE;
PercentType[] rgbw = ColorUtil.hsbToRgbwPercent(hsb);
assertEquals(0.0, rgbw[0].doubleValue(), 0.01);
assertEquals(0.0, rgbw[1].doubleValue(), 0.01);
assertEquals(0.0, rgbw[2].doubleValue(), 0.01);
assertEquals(100.0, rgbw[3].doubleValue(), 0.01);

hsb = HSBType.BLACK;
rgbw = ColorUtil.hsbToRgbwPercent(hsb);
assertEquals(0.0, rgbw[0].doubleValue(), 0.01);
assertEquals(0.0, rgbw[1].doubleValue(), 0.01);
assertEquals(0.0, rgbw[2].doubleValue(), 0.01);
assertEquals(0.0, rgbw[3].doubleValue(), 0.01);

hsb = HSBType.RED;
rgbw = ColorUtil.hsbToRgbwPercent(hsb);
assertEquals(100.0, rgbw[0].doubleValue(), 0.01);
assertEquals(0.0, rgbw[1].doubleValue(), 0.01);
assertEquals(0.0, rgbw[2].doubleValue(), 0.01);
assertEquals(0.0, rgbw[3].doubleValue(), 0.01);

hsb = HSBType.GREEN;
rgbw = ColorUtil.hsbToRgbwPercent(hsb);
assertEquals(0.0, rgbw[0].doubleValue(), 0.01);
assertEquals(100.0, rgbw[1].doubleValue(), 0.01);
assertEquals(0.0, rgbw[2].doubleValue(), 0.01);
assertEquals(0.0, rgbw[3].doubleValue(), 0.01);

hsb = HSBType.BLUE;
rgbw = ColorUtil.hsbToRgbwPercent(hsb);
assertEquals(0.0, rgbw[0].doubleValue(), 0.01);
assertEquals(0.0, rgbw[1].doubleValue(), 0.01);
assertEquals(100.0, rgbw[2].doubleValue(), 0.01);
assertEquals(0.0, rgbw[3].doubleValue(), 0.01);
}

public void rgbwtohsbTest() {
// Test Red
HSBType hsb = ColorUtil.rgbwTohsb(255, 0, 0, 0);
int[] convertedRgb = ColorUtil.hsbToRgb(hsb);
assertRgbEquals(new int[] { 255, 0, 0 }, convertedRgb);

// Test Green
hsb = ColorUtil.rgbwTohsb(0, 255, 0, 0);
convertedRgb = ColorUtil.hsbToRgb(hsb);
assertRgbEquals(new int[] { 0, 255, 0 }, convertedRgb);

// Test Blue
hsb = ColorUtil.rgbwTohsb(0, 0, 255, 0);
convertedRgb = ColorUtil.hsbToRgb(hsb);
assertRgbEquals(new int[] { 0, 0, 255 }, convertedRgb);

// Test White
hsb = ColorUtil.rgbwTohsb(0, 0, 0, 255);
convertedRgb = ColorUtil.hsbToRgb(hsb);
assertRgbEquals(new int[] { 255, 255, 255 }, convertedRgb);

// Test Black
hsb = ColorUtil.rgbwTohsb(0, 0, 0, 0);
convertedRgb = ColorUtil.hsbToRgb(hsb);
assertRgbEquals(new int[] { 0, 0, 0 }, convertedRgb);
}

@ParameterizedTest
@MethodSource("invalids")
public void invalidXyValues(double[] xy) {
Expand Down

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