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Commit 1ca52e44 authored by Daniel Solomon's avatar Daniel Solomon
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Add API to ColorSpace to compute chromaticity coordinates from CCT 

Add a ColorSpace API that computes the chromaticity coordinates of a CIE
series D illuminant from the specified correlated color temperature.

Test: cts-tradefed run singleCommand cts-dev --module CtsGraphicsTestCases --test android.graphics.cts.ColorSpaceTest
Bug 116516917

Change-Id: I6c9f2a23ed548556d5fbdcc22ed5a094a76bb8e4
parent 122c0879

api/current.txt

+1 −0
Original line number Diff line number Diff line
@@ -13727,6 +13727,7 @@ package android.graphics { 
  public abstract class ColorSpace {

    method public static android.graphics.ColorSpace adapt(android.graphics.ColorSpace, float[]);

    method public static android.graphics.ColorSpace adapt(android.graphics.ColorSpace, float[], android.graphics.ColorSpace.Adaptation);

    method public static float[] cctToIlluminantdXyz(int);

    method public static float[] chromaticAdaptation(android.graphics.ColorSpace.Adaptation, float[], float[]);

    method public static android.graphics.ColorSpace.Connector connect(android.graphics.ColorSpace, android.graphics.ColorSpace);

    method public static android.graphics.ColorSpace.Connector connect(android.graphics.ColorSpace, android.graphics.ColorSpace, android.graphics.ColorSpace.RenderIntent);

graphics/java/android/graphics/ColorSpace.java

+30 −0
Original line number Diff line number Diff line
@@ -1778,6 +1778,36 @@ public abstract class ColorSpace { 
        return mul3x3(inverse3x3(matrix), mul3x3Diag(LMS, matrix));

    }



    /**

     * <p>Computes the chromaticity coordinates of a CIE series D illuminant

     * from the specified correlated color temperature (CCT). The specified CCT

     * must be greater than 0. A meaningful CCT range is [4000, 25000].</p>

     *

     * <p>The transform is computed using the methods referred to in Kang et

     * al., <i>Design of Advanced Color - Temperature Control System for HDTV

     * Applications</i>, Journal of Korean Physical Society 41, 865-871

     * (2002).</p>

     *

     * @param cct The correlated color temperature, in Kelvin

     * @return Corresponding XYZ values

     * @throws IllegalArgumentException If cct is invalid

     */

    @NonNull

    @Size(3)

    public static float[] cctToIlluminantdXyz(@IntRange(from = 1) int cct) {

        if (cct < 1) {

            throw new IllegalArgumentException("Temperature must be greater than 0");

        }



        final float icct = 1.0f / cct;

        final float icct2 = icct * icct;

        final float x = cct <= 7000.0f ?

            0.244063f + 0.09911e3f * icct + 2.9678e6f * icct2 - 4.6070e9f * icct2 * icct :

            0.237040f + 0.24748e3f * icct + 1.9018e6f * icct2 - 2.0064e9f * icct2 * icct;

        final float y = -3.0f * x * x + 2.87f * x - 0.275f;

        return xyYToXyz(new float[] {x, y});

    }



    /**

     * <p>Computes the chromatic adaptation transform from the specified

     * source white point to the specified destination white point.</p>