ColorGradient.m

classdef ColorGradient < handle
    properties
        color
        
        minValue
        maxValue
        span
    end
    
    methods
        function obj = ColorGradient(minValue, maxValue)
            obj.minValue = 0.0;
            obj.maxValue = 1.0;
            
             if nargin > 0          
                obj.minValue = minValue;
                obj.maxValue = maxValue;
             end
             
             obj.span = obj.maxValue - obj.minValue;
             
             obj.SetColorGradientType(GradientType.Jet)
        end
        
        function SetColorGradientType(obj, type)
            switch type
                case GradientType.Jet
                    obj.SetGradientTypeJet();
                case GradientType.Parula
                    obj.SetGradientTypeParula();
                otherwise
                    obj.SetGradientTypeJet();
            end
        end
        
        function SetGradientTypeJet(obj)
            obj.color = [0.0 0.0 0.5 0.0;
                 0.0 0.0 1.0 0.125;
                 0.0 0.5 1.0 0.250;
                 0.0 1.0 1.0 0.375;
                 0.5 1.0 0.5 0.500;
                 1.0 1.0 0.0 0.625;
                 1.0 0.5 0.0 0.750;
                 1.0 0.0 0.0 0.875;
                 0.5 0.0 0.0 1.000];
        end
        
        function SetGradientTypeParula(obj)
            v = parulaColors();
            n = linspace(0, 1, size(v, 1))';
            obj.color = [v n];
        end
        
        function col = ColorAtValue(obj, val)
            val = (val - obj.minValue) / obj.span;
            
            indexMask = zeros(size(val));
            residualMask = true(size(val));
            
            for i = 1 : size(obj.color, 1)
                indexMask(residualMask) = i;
                residualMask(residualMask == true) = ...
                    ~(val(residualMask) <= obj.color(i, 4) & residualMask(residualMask == true));
            end
            
            red = obj.color(:, 1);
            green = obj.color(:, 2);
            blue = obj.color(:, 3);
            v = obj.color(:, 4);
            
            currRed = red(indexMask);
            currGreen = green(indexMask);
            currBlue = blue(indexMask);
            currVal = v(indexMask);
            
            prevRed = red(max(1, indexMask - 1));
            prevGreen = green(max(1, indexMask - 1));
            prevBlue = blue(max(1, indexMask - 1));
            prevVal = v(max(1, indexMask - 1));
            
            valueDiff = currVal - prevVal;
            
            lambda1 = zeros(size(valueDiff));
            nonZeroInd = valueDiff > 0;
            lambda1(nonZeroInd) = (currVal(nonZeroInd) - val(nonZeroInd)) ./ valueDiff(nonZeroInd);
            lambda2 = 1 - lambda1;
            
            r = lambda1 .* prevRed   + lambda2 .* currRed;
            g = lambda1 .* prevGreen + lambda2 .* currGreen;
            b = lambda1 .* prevBlue  + lambda2 .* currBlue;
            
            col = cat(3, r, g, b);
        end        
    end
end

function values = parulaColors()
    values = [
    0.2422 0.1504 0.6603
    0.2444 0.1534 0.6728
    0.2464 0.1569 0.6847
    0.2484 0.1607 0.6961
    0.2503 0.1648 0.7071
    0.2522 0.1689 0.7179
    0.2540 0.1732 0.7286
    0.2558 0.1773 0.7393
    0.2576 0.1814 0.7501
    0.2594 0.1854 0.7610
    0.2611 0.1893 0.7719
    0.2628 0.1932 0.7828
    0.2645 0.1972 0.7937
    0.2661 0.2011 0.8043
    0.2676 0.2052 0.8148
    0.2691 0.2094 0.8249
    0.2704 0.2138 0.8346
    0.2717 0.2184 0.8439
    0.2729 0.2231 0.8528
    0.2740 0.2280 0.8612
    0.2749 0.2330 0.8692
    0.2758 0.2382 0.8767
    0.2766 0.2435 0.8840
    0.2774 0.2489 0.8908
    0.2781 0.2543 0.8973
    0.2788 0.2598 0.9035
    0.2794 0.2653 0.9094
    0.2798 0.2708 0.9150
    0.2802 0.2764 0.9204
    0.2806 0.2819 0.9255
    0.2809 0.2875 0.9305
    0.2811 0.2930 0.9352
    0.2813 0.2985 0.9397
    0.2814 0.3040 0.9441
    0.2814 0.3095 0.9483
    0.2813 0.3150 0.9524
    0.2811 0.3204 0.9563
    0.2809 0.3259 0.9600
    0.2807 0.3313 0.9636
    0.2803 0.3367 0.9670
    0.2798 0.3421 0.9702
    0.2791 0.3475 0.9733
    0.2784 0.3529 0.9763
    0.2776 0.3583 0.9791
    0.2766 0.3638 0.9817
    0.2754 0.3693 0.9840
    0.2741 0.3748 0.9862
    0.2726 0.3804 0.9881
    0.2710 0.3860 0.9898
    0.2691 0.3916 0.9912
    0.2670 0.3973 0.9924
    0.2647 0.4030 0.9935
    0.2621 0.4088 0.9946
    0.2591 0.4145 0.9955
    0.2556 0.4203 0.9965
    0.2517 0.4261 0.9974
    0.2473 0.4319 0.9983
    0.2424 0.4378 0.9991
    0.2369 0.4437 0.9996
    0.2311 0.4497 0.9995
    0.2250 0.4559 0.9985
    0.2189 0.4620 0.9968
    0.2128 0.4682 0.9948
    0.2066 0.4743 0.9926
    0.2006 0.4803 0.9906
    0.1950 0.4861 0.9887
    0.1903 0.4919 0.9867
    0.1869 0.4975 0.9844
    0.1847 0.5030 0.9819
    0.1831 0.5084 0.9793
    0.1818 0.5138 0.9766
    0.1806 0.5191 0.9738
    0.1795 0.5244 0.9709
    0.1785 0.5296 0.9677
    0.1778 0.5349 0.9641
    0.1773 0.5401 0.9602
    0.1768 0.5452 0.9560
    0.1764 0.5504 0.9516
    0.1755 0.5554 0.9473
    0.1740 0.5605 0.9432
    0.1716 0.5655 0.9393
    0.1686 0.5705 0.9357
    0.1649 0.5755 0.9323
    0.1610 0.5805 0.9289
    0.1573 0.5854 0.9254
    0.1540 0.5902 0.9218
    0.1513 0.5950 0.9182
    0.1492 0.5997 0.9147
    0.1475 0.6043 0.9113
    0.1461 0.6089 0.9080
    0.1446 0.6135 0.9050
    0.1429 0.6180 0.9022
    0.1408 0.6226 0.8998
    0.1383 0.6272 0.8975
    0.1354 0.6317 0.8953
    0.1321 0.6363 0.8932
    0.1288 0.6408 0.8910
    0.1253 0.6453 0.8887
    0.1219 0.6497 0.8862
    0.1185 0.6541 0.8834
    0.1152 0.6584 0.8804
    0.1119 0.6627 0.8770
    0.1085 0.6669 0.8734
    0.1048 0.6710 0.8695
    0.1009 0.6750 0.8653
    0.0964 0.6789 0.8609
    0.0914 0.6828 0.8562
    0.0855 0.6865 0.8513
    0.0789 0.6902 0.8462
    0.0713 0.6938 0.8409
    0.0628 0.6972 0.8355
    0.0535 0.7006 0.8299
    0.0433 0.7039 0.8242
    0.0328 0.7071 0.8183
    0.0234 0.7103 0.8124
    0.0155 0.7133 0.8064
    0.0091 0.7163 0.8003
    0.0046 0.7192 0.7941
    0.0019 0.7220 0.7878
    0.0009 0.7248 0.7815
    0.0018 0.7275 0.7752
    0.0046 0.7301 0.7688
    0.0094 0.7327 0.7623
    0.0162 0.7352 0.7558
    0.0253 0.7376 0.7492
    0.0369 0.7400 0.7426
    0.0504 0.7423 0.7359
    0.0638 0.7446 0.7292
    0.0770 0.7468 0.7224
    0.0899 0.7489 0.7156
    0.1023 0.7510 0.7088
    0.1141 0.7531 0.7019
    0.1252 0.7552 0.6950
    0.1354 0.7572 0.6881
    0.1448 0.7593 0.6812
    0.1532 0.7614 0.6741
    0.1609 0.7635 0.6671
    0.1678 0.7656 0.6599
    0.1741 0.7678 0.6527
    0.1799 0.7699 0.6454
    0.1853 0.7721 0.6379
    0.1905 0.7743 0.6303
    0.1954 0.7765 0.6225
    0.2003 0.7787 0.6146
    0.2061 0.7808 0.6065
    0.2118 0.7828 0.5983
    0.2178 0.7849 0.5899
    0.2244 0.7869 0.5813
    0.2318 0.7887 0.5725
    0.2401 0.7905 0.5636
    0.2491 0.7922 0.5546
    0.2589 0.7937 0.5454
    0.2695 0.7951 0.5360
    0.2809 0.7964 0.5266
    0.2929 0.7975 0.5170
    0.3052 0.7985 0.5074
    0.3176 0.7994 0.4975
    0.3301 0.8002 0.4876
    0.3424 0.8009 0.4774
    0.3548 0.8016 0.4669
    0.3671 0.8021 0.4563
    0.3795 0.8026 0.4454
    0.3921 0.8029 0.4344
    0.4050 0.8031 0.4233
    0.4184 0.8030 0.4122
    0.4322 0.8028 0.4013
    0.4463 0.8024 0.3904
    0.4608 0.8018 0.3797
    0.4753 0.8011 0.3691
    0.4899 0.8002 0.3586
    0.5044 0.7993 0.3480
    0.5187 0.7982 0.3374
    0.5329 0.7970 0.3267
    0.5470 0.7957 0.3159
    0.5609 0.7943 0.3050
    0.5748 0.7929 0.2941
    0.5886 0.7913 0.2833
    0.6024 0.7896 0.2726
    0.6161 0.7878 0.2622
    0.6297 0.7859 0.2521
    0.6433 0.7839 0.2423
    0.6567 0.7818 0.2329
    0.6701 0.7796 0.2239
    0.6833 0.7773 0.2155
    0.6963 0.7750 0.2075
    0.7091 0.7727 0.1998
    0.7218 0.7703 0.1924
    0.7344 0.7679 0.1852
    0.7468 0.7654 0.1782
    0.7590 0.7629 0.1717
    0.7710 0.7604 0.1658
    0.7829 0.7579 0.1608
    0.7945 0.7554 0.1570
    0.8060 0.7529 0.1546
    0.8172 0.7505 0.1535
    0.8281 0.7481 0.1536
    0.8389 0.7457 0.1546
    0.8495 0.7435 0.1564
    0.8600 0.7413 0.1587
    0.8703 0.7392 0.1615
    0.8804 0.7372 0.1650
    0.8903 0.7353 0.1695
    0.9000 0.7336 0.1749
    0.9093 0.7321 0.1815
    0.9184 0.7308 0.1890
    0.9272 0.7298 0.1973
    0.9357 0.7290 0.2061
    0.9440 0.7285 0.2151
    0.9523 0.7284 0.2237
    0.9606 0.7285 0.2312
    0.9689 0.7292 0.2373
    0.9770 0.7304 0.2418
    0.9842 0.7330 0.2446
    0.9900 0.7365 0.2429
    0.9946 0.7407 0.2394
    0.9966 0.7458 0.2351
    0.9971 0.7513 0.2309
    0.9972 0.7569 0.2267
    0.9971 0.7626 0.2224
    0.9969 0.7683 0.2181
    0.9966 0.7740 0.2138
    0.9962 0.7798 0.2095
    0.9957 0.7856 0.2053
    0.9949 0.7915 0.2012
    0.9938 0.7974 0.1974
    0.9923 0.8034 0.1939
    0.9906 0.8095 0.1906
    0.9885 0.8156 0.1875
    0.9861 0.8218 0.1846
    0.9835 0.8280 0.1817
    0.9807 0.8342 0.1787
    0.9778 0.8404 0.1757
    0.9748 0.8467 0.1726
    0.9720 0.8529 0.1695
    0.9694 0.8591 0.1665
    0.9671 0.8654 0.1636
    0.9651 0.8716 0.1608
    0.9634 0.8778 0.1582
    0.9619 0.8840 0.1557
    0.9608 0.8902 0.1532
    0.9601 0.8963 0.1507
    0.9596 0.9023 0.1480
    0.9595 0.9084 0.1450
    0.9597 0.9143 0.1418
    0.9601 0.9203 0.1382
    0.9608 0.9262 0.1344
    0.9618 0.9320 0.1304
    0.9629 0.9379 0.1261
    0.9642 0.9437 0.1216
    0.9657 0.9494 0.1168
    0.9674 0.9552 0.1116
    0.9692 0.9609 0.1061
    0.9711 0.9667 0.1001
    0.9730 0.9724 0.0938
    0.9749 0.9782 0.0872
    0.9769 0.9839 0.0805
    ];
end