diff --git a/src/main/java/org/apache/commons/imaging/color/ColorConversions.java b/src/main/java/org/apache/commons/imaging/color/ColorConversions.java
index 4b2570107..7f290f1f4 100644
--- a/src/main/java/org/apache/commons/imaging/color/ColorConversions.java
+++ b/src/main/java/org/apache/commons/imaging/color/ColorConversions.java
@@ -177,16 +177,16 @@ public static ColorXyz convertRGBtoXYZ(final int rgb) {
     }
 
     public static ColorCmy convertRGBtoCMY(final int rgb) {
+        // CMY values = 0 ÷ 100
+        // RGB values = 0 ÷ 255
+        
         final int R = 0xff & (rgb >> 16);
         final int G = 0xff & (rgb >> 8);
         final int B = 0xff & (rgb >> 0);
 
-        // RGB values = 0 ÷ 255
-        // CMY values = 0 ÷ 1
-
-        final double C = 1 - (R / 255.0);
-        final double M = 1 - (G / 255.0);
-        final double Y = 1 - (B / 255.0);
+        final double C = (1 - (R / 255.0))*100.0;
+        final double M = (1 - (G / 255.0))*100.0;
+        final double Y = (1 - (B / 255.0))*100.0;
 
         return new ColorCmy(C, M, Y);
     }
@@ -198,24 +198,23 @@ public static int convertCMYtoRGB(final ColorCmy cmy) {
         // and similarly for G and B.
         // This is Ghostscript's formula with K = 0.
 
-        // CMY values = 0 ÷ 1
+        // CMY values = 0 ÷ 100
         // RGB values = 0 ÷ 255
 
-        final double R = (1 - cmy.C) * 255.0;
-        final double G = (1 - cmy.M) * 255.0;
-        final double B = (1 - cmy.Y) * 255.0;
-
+        final double R = (1 - cmy.C / 100) * 255.0;
+        final double G = (1 - cmy.M / 100) * 255.0;
+        final double B = (1 - cmy.Y / 100) * 255.0;
+        
         return convertRGBtoRGB(R, G, B);
     }
 
     public static ColorCmyk convertCMYtoCMYK(final ColorCmy cmy) {
-        // Where CMYK and CMY values = 0 ÷ 1
+        // Where CMYK and CMY values = 0 ÷ 100
 
         double C = cmy.C;
         double M = cmy.M;
         double Y = cmy.Y;
-
-        double var_K = 1.0;
+        double var_K = 100.0;
 
         if (C < var_K) {
             var_K = C;
@@ -226,15 +225,16 @@ public static ColorCmyk convertCMYtoCMYK(final ColorCmy cmy) {
         if (Y < var_K) {
             var_K = Y;
         }
-        if (var_K == 1) { // Black
+        if (var_K == 100.0) { // Black
             C = 0;
             M = 0;
             Y = 0;
         } else {
-            C = (C - var_K) / (1 - var_K);
-            M = (M - var_K) / (1 - var_K);
-            Y = (Y - var_K) / (1 - var_K);
+            C = (C - var_K) / (1 - var_K / 100.0);
+            M = (M - var_K) / (1 - var_K / 100.0);
+            Y = (Y - var_K) / (1 - var_K / 100.0);
         }
+
         return new ColorCmyk(C, M, Y, var_K);
     }
 
@@ -244,21 +244,15 @@ public static ColorCmy convertCMYKtoCMY(final ColorCmyk cmyk) {
 
     public static ColorCmy convertCMYKtoCMY(double C, double M, double Y,
             final double K) {
-        // Where CMYK and CMY values = 0 ÷ 1
-
-        C = (C * (1 - K) + K);
-        M = (M * (1 - K) + K);
-        Y = (Y * (1 - K) + K);
+        // Where CMYK and CMY values = 0 ÷ 100
 
+        C = C * (1 - K / 100.0) + K;
+        M = M * (1 - K / 100.0) + K;
+        Y = Y * (1 - K / 100.0) + K;
         return new ColorCmy(C, M, Y);
     }
 
-    public static int convertCMYKtoRGB(final int c, final int m, final int y, final int k) {
-        final double C = c / 255.0;
-        final double M = m / 255.0;
-        final double Y = y / 255.0;
-        final double K = k / 255.0;
-
+    public static int convertCMYKtoRGB(final double C, final double M, final double Y, final double K) {
         return convertCMYtoRGB(convertCMYKtoCMY(C, M, Y, K));
     }
 
@@ -272,6 +266,7 @@ public static ColorHsl convertRGBtoHSL(final int rgb) {
         final double var_G = (G / 255.0);
         final double var_B = (B / 255.0);
 
+
         final double var_Min = Math.min(var_R, Math.min(var_G, var_B)); // Min. value
                                                                   // of RGB
         double var_Max;
@@ -334,7 +329,7 @@ public static ColorHsl convertRGBtoHSL(final int rgb) {
             // Debug.debug("H2", H);
         }
 
-        return new ColorHsl(H, S, L);
+        return new ColorHsl(H, S*100, L*100);
     }
 
     public static int convertHSLtoRGB(final ColorHsl hsl) {
@@ -346,19 +341,19 @@ public static int convertHSLtoRGB(final double H, final double S, final double L
 
         if (S == 0) {
             // HSL values = 0 ÷ 1
-            R = L * 255; // RGB results = 0 ÷ 255
-            G = L * 255;
-            B = L * 255;
+            R = L * 2.55; // RGB results = 0 ÷ 255
+            G = L * 2.55;
+            B = L * 2.55;
         } else {
             double var_2;
 
             if (L < 0.5) {
-                var_2 = L * (1 + S);
+                var_2 = L/100 * (1 + S/100);
             } else {
-                var_2 = (L + S) - (S * L);
+                var_2 = (L/100 + S/100) - (S/100 * L/100);
             }
 
-            final double var_1 = 2 * L - var_2;
+            final double var_1 = 2 * L/100 - var_2;
 
             R = 255 * convertHuetoRGB(var_1, var_2, H + (1 / 3.0));
             G = 255 * convertHuetoRGB(var_1, var_2, H);
@@ -388,61 +383,40 @@ private static double convertHuetoRGB(final double v1, final double v2, double v
     }
 
     public static ColorHsv convertRGBtoHSV(final int rgb) {
+        double H = 0;
+        double S = 0;
+        double V = 0;
+
         final int R = 0xff & (rgb >> 16);
         final int G = 0xff & (rgb >> 8);
         final int B = 0xff & (rgb >> 0);
 
-        final double var_R = (R / 255.0); // RGB values = 0 ÷ 255
-        final double var_G = (G / 255.0);
-        final double var_B = (B / 255.0);
-
-        final double var_Min = Math.min(var_R, Math.min(var_G, var_B)); // Min. value
-                                                                  // of RGB
-        boolean maxIsR = false;
-        boolean maxIsG = false;
-        double var_Max;
-        if (var_R >= var_G && var_R >= var_B) {
-            var_Max = var_R;
-            maxIsR = true;
-        } else if (var_G > var_B) {
-            var_Max = var_G;
-            maxIsG = true;
-        } else {
-            var_Max = var_B;
+        final double R1 = (R / 255.0); // RGB values = 0 ÷ 255
+        final double G1 = (G / 255.0);
+        final double B1 = (B / 255.0);
+
+        double Cmax = Math.max(R1, Math.max(G1, B1));
+        double Cmin = Math.min(R1, Math.min(G1, B1));
+        double delta = Cmax - Cmin;
+
+        if(delta == 0){
+          H = 0;
+        }else if(Cmax == B1){
+          H = Math.abs(60 * (((R1-G1)/delta) + 4));
+        }else if(Cmax == G1){
+          H = Math.abs(60 * (((B1-R1)/delta) + 2));
+        }else if(Cmax == R1){
+          H = Math.abs(60 * (((G1-B1)/delta) % 6));
         }
-        final double del_Max = var_Max - var_Min; // Delta RGB value
-
-        final double V = var_Max;
-
-        double H, S;
-        if (del_Max == 0) {
-            // This is a gray, no chroma...
-            H = 0; // HSV results = 0 ÷ 1
-            S = 0;
-        } else {
-        // Chromatic data...
-            S = del_Max / var_Max;
-
-            final double del_R = (((var_Max - var_R) / 6) + (del_Max / 2)) / del_Max;
-            final double del_G = (((var_Max - var_G) / 6) + (del_Max / 2)) / del_Max;
-            final double del_B = (((var_Max - var_B) / 6) + (del_Max / 2)) / del_Max;
-
-            if (maxIsR) {
-                H = del_B - del_G;
-            } else if (maxIsG) {
-                H = (1 / 3.0) + del_R - del_B;
-            } else {
-                H = (2 / 3.0) + del_G - del_R;
-            }
 
-            if (H < 0) {
-                H += 1;
-            }
-            if (H > 1) {
-                H -= 1;
-            }
+        if(Cmax == 0){
+          S = 0;
+        } else{
+          S = (delta / Cmax)*100;
         }
 
+        V = Cmax*100;
+
         return new ColorHsv(H, S, V);
     }
 
@@ -453,54 +427,46 @@ public static int convertHSVtoRGB(final ColorHsv HSV) {
     public static int convertHSVtoRGB(final double H, final double S, final double V) {
         double R, G, B;
 
-        if (S == 0) {
-            // HSV values = 0 ÷ 1
-            R = V * 255;
-            G = V * 255;
-            B = V * 255;
-        } else {
-            double var_h = H * 6;
-            if (var_h == 6) {
-                var_h = 0; // H must be < 1
-            }
-            final double var_i = Math.floor(var_h); // Or ... var_i = floor( var_h )
-            final double var_1 = V * (1 - S);
-            final double var_2 = V * (1 - S * (var_h - var_i));
-            final double var_3 = V * (1 - S * (1 - (var_h - var_i)));
-
-            double var_r, var_g, var_b;
-
-            if (var_i == 0) {
-                var_r = V;
-                var_g = var_3;
-                var_b = var_1;
-            } else if (var_i == 1) {
-                var_r = var_2;
-                var_g = V;
-                var_b = var_1;
-            } else if (var_i == 2) {
-                var_r = var_1;
-                var_g = V;
-                var_b = var_3;
-            } else if (var_i == 3) {
-                var_r = var_1;
-                var_g = var_2;
-                var_b = V;
-            } else if (var_i == 4) {
-                var_r = var_3;
-                var_g = var_1;
-                var_b = V;
-            } else {
-                var_r = V;
-                var_g = var_1;
-                var_b = var_2;
-            }
-
-            R = var_r * 255; // RGB results = 0 ÷ 255
-            G = var_g * 255;
-            B = var_b * 255;
+        double s = S/100;
+        double v = V/100;
+
+        double C = (v * s);
+        double X = C * (1 - Math.abs((H/60) % 2 - 1));
+        double m = v - C;
+
+        double R1 = 0;
+        double G1 = 0;
+        double B1 = 0;
+
+        if(0 <= H && H < 60){
+          R1 = C;
+          G1 = X;
+          B1 = 0;
+        }else if(60 <= H && H < 120){
+          R1 = X;
+          G1 = C;
+          B1 = 0;
+        }else if(120 <= H && H < 180){
+          R1 = 0;
+          G1 = C;
+          B1 = X;
+        }else if(180 <= H && H < 240){
+          R1 = 0;
+          G1 = X;
+          B1 = C;
+        }else if(240 <= H && H < 300){
+          R1 = X;
+          G1 = 0;
+          B1 = C;
+        }else if(300 <= H && H < 360){
+          R1 = C;
+          G1 = 0;
+          B1 = X;
         }
 
+        R = (R1+m)*255;
+        G = (G1+m)*255;
+        B = (B1+m)*255;
         return convertRGBtoRGB(R, G, B);
     }
 
diff --git a/src/main/java/org/apache/commons/imaging/formats/jpeg/decoder/JpegDecoder.java b/src/main/java/org/apache/commons/imaging/formats/jpeg/decoder/JpegDecoder.java
index 1956625d0..16b9039b0 100644
--- a/src/main/java/org/apache/commons/imaging/formats/jpeg/decoder/JpegDecoder.java
+++ b/src/main/java/org/apache/commons/imaging/formats/jpeg/decoder/JpegDecoder.java
@@ -167,10 +167,10 @@ public void visitSOS(final int marker, final byte[] markerBytes, final byte[] im
                         for (int x2 = 0; x2 < hSize
                                 && x1 + x2 < sofnSegment.width; x2++) {
                             if (scaledMCU.length == 4) {
-                                final int C = scaledMCU[0].samples[srcRowOffset + x2];
-                                final int M = scaledMCU[1].samples[srcRowOffset + x2];
-                                final int Y = scaledMCU[2].samples[srcRowOffset + x2];
-                                final int K = scaledMCU[3].samples[srcRowOffset + x2];
+                                final double C = scaledMCU[0].samples[srcRowOffset + x2] / 2.550;
+                                final double M = scaledMCU[1].samples[srcRowOffset + x2] / 2.550;
+                                final double Y = scaledMCU[2].samples[srcRowOffset + x2] / 2.550;
+                                final double K = scaledMCU[3].samples[srcRowOffset + x2] / 2.550;
                                 final int rgb = ColorConversions.convertCMYKtoRGB(C, M, Y, K);
                                 dataBuffer.setElem(dstRowOffset + x2, rgb);
                             } else if (scaledMCU.length == 3) {
diff --git a/src/main/java/org/apache/commons/imaging/formats/psd/dataparsers/DataParserCmyk.java b/src/main/java/org/apache/commons/imaging/formats/psd/dataparsers/DataParserCmyk.java
index e0ea8a777..cc93ec4ea 100644
--- a/src/main/java/org/apache/commons/imaging/formats/psd/dataparsers/DataParserCmyk.java
+++ b/src/main/java/org/apache/commons/imaging/formats/psd/dataparsers/DataParserCmyk.java
@@ -29,12 +29,12 @@ protected int getRGB(final int[][][] data, final int x, final int y,
         int sk = 0xff & data[3][y][x];
 
         // CRAZY adobe has to store the bytes in reverse form.
-        sc = 255 - sc;
-        sm = 255 - sm;
-        sy = 255 - sy;
-        sk = 255 - sk;
+        final double SC = 100 - sc/2.550;
+        final double SM = 100 - sm/2.550;
+        final double SY = 100 - sy/2.550;
+        final double SK = 100 - sk/2.550;
 
-        return ColorConversions.convertCMYKtoRGB(sc, sm, sy, sk);
+        return ColorConversions.convertCMYKtoRGB(SC, SM, SY, SK);
     }
 
     @Override
diff --git a/src/main/java/org/apache/commons/imaging/formats/tiff/photometricinterpreters/PhotometricInterpreterCmyk.java b/src/main/java/org/apache/commons/imaging/formats/tiff/photometricinterpreters/PhotometricInterpreterCmyk.java
index f9ac08b43..7fdaed974 100644
--- a/src/main/java/org/apache/commons/imaging/formats/tiff/photometricinterpreters/PhotometricInterpreterCmyk.java
+++ b/src/main/java/org/apache/commons/imaging/formats/tiff/photometricinterpreters/PhotometricInterpreterCmyk.java
@@ -32,10 +32,10 @@ public PhotometricInterpreterCmyk(final int samplesPerPixel,
     public void interpretPixel(final ImageBuilder imageBuilder, final int[] samples, final int x,
             final int y) throws ImageReadException, IOException {
 
-        final int sc = samples[0];
-        final int sm = samples[1];
-        final int sy = samples[2];
-        final int sk = samples[3];
+        final double sc = samples[0]/2.550;
+        final double sm = samples[1]/2.550;
+        final double sy = samples[2]/2.550;
+        final double sk = samples[3]/2.550;
 
         final int rgb = ColorConversions.convertCMYKtoRGB(sc, sm, sy, sk);
         imageBuilder.setRGB(x, y, rgb);
diff --git a/src/test/java/org/apache/commons/imaging/color/ColorConversionsTest.java b/src/test/java/org/apache/commons/imaging/color/ColorConversionsTest.java
index f88614c6f..abb8e7fa6 100644
--- a/src/test/java/org/apache/commons/imaging/color/ColorConversionsTest.java
+++ b/src/test/java/org/apache/commons/imaging/color/ColorConversionsTest.java
@@ -44,6 +44,20 @@ public void testRGBtoCMYK() {
         }
     }
 
+    @Test
+    public void testCMYKtoCMYtoRGBtoCMYtoCMYK() {
+        int magentaRGB = ColorConversions.convertCMYtoRGB(ColorConversions.convertCMYKtoCMY(ColorCmyk.MAGENTA));
+        assertEquals(ColorCmyk.MAGENTA, ColorConversions.convertCMYtoCMYK(ColorConversions.convertRGBtoCMY(magentaRGB)));
+    }
+
+    @Test
+    public void testCMYtoCMYKtoCMY() {
+        for(int i = 0; i<5; i++){
+            ColorCmy cmy1 = new ColorCmy(10 + 12 * i, 15*i, 60/(i+1));
+            assertEquals(cmy1, ColorConversions.convertCMYKtoCMY(ColorConversions.convertCMYtoCMYK(cmy1)));
+        }
+    }
+ 
     @Test
     public void testRGBtoHSL() {
         for (final int rgb : SAMPLE_RGBS) {
@@ -57,12 +71,16 @@ public void testRGBtoHSL() {
         }
     }
 
+    @Test
+    public void testHSLtoRGBtoHSL() {
+        assertEquals(ColorHsl.BLACK, ColorConversions.convertRGBtoHSL(ColorConversions.convertHSLtoRGB(ColorHsl.BLACK)));
+    }
+
     @Test
     public void testRGBtoHSV() {
         for (final int rgb : SAMPLE_RGBS) {
             final ColorHsv hsv = ColorConversions.convertRGBtoHSV(rgb);
             final int hsv_rgb = ColorConversions.convertHSVtoRGB(hsv);
-
             Debug.debug("hsv: " + hsv);
             Debug.debug("hsv_rgb: " + hsv_rgb + " (" + Integer.toHexString(hsv_rgb) + ")");
 
@@ -70,6 +88,11 @@ public void testRGBtoHSV() {
         }
     }
 
+    @Test
+    public void testHSVtoRGBtoHSV() {
+        assertEquals(ColorHsv.BLUE, ColorConversions.convertRGBtoHSV(ColorConversions.convertHSVtoRGB(ColorHsv.BLUE)));
+    }
+
     @Test
     public void testXYZ() {
         for (final int rgb : SAMPLE_RGBS) {
@@ -118,6 +141,32 @@ public void testXYZ() {
         }
     }
 
+    @Test
+    public void testCIELabtoXYZtoRGBtoXYZtoCIELab() {
+        int greenRGB = ColorConversions.convertXYZtoRGB(ColorConversions.convertCIELabtoXYZ(ColorCieLab.GREEN));
+        ColorCieLab greehCIELab = ColorConversions.convertXYZtoCIELab(ColorConversions.convertRGBtoXYZ(greenRGB));
+        assertEquals(ColorCieLab.GREEN.L, greehCIELab.L, 0.3);
+        assertEquals(ColorCieLab.GREEN.a, greehCIELab.a, 0.3);
+        assertEquals(ColorCieLab.GREEN.b, greehCIELab.b, 0.3);
+    }
+
+    @Test
+    public void testCIELUVtoXYZtoRGBtoXYZtoCIELUV() {
+        int whiteRGB = ColorConversions.convertXYZtoRGB(ColorConversions.convertCIELuvtoXYZ(ColorCieLuv.WHITE));
+        ColorCieLuv whiteCIELuv = ColorConversions.convertXYZtoCIELuv(ColorConversions.convertRGBtoXYZ(whiteRGB));
+        assertEquals(ColorCieLuv.WHITE.L, whiteCIELuv.L,  0.1);
+        assertEquals(ColorCieLuv.WHITE.u, whiteCIELuv.u,  0.1);
+        assertEquals(ColorCieLuv.WHITE.v, whiteCIELuv.v,  0.1);
+    }
+
+    @Test
+    public void testCIELchtoCIELabtoCIELch() {
+        ColorCieLch redCIELch = ColorConversions.convertCIELabtoCIELCH(ColorConversions.convertCIELCHtoCIELab(ColorCieLch.RED));
+        assertEquals(ColorCieLch.RED.L, redCIELch.L, 0.1);
+        assertEquals(ColorCieLch.RED.C, redCIELch.C, 0.1);
+        assertEquals(ColorCieLch.RED.h, redCIELch.h, 0.1);
+    }
+
     @Test
     public void testRGBtoDin99b() {
         for (final int rgb : SAMPLE_RGBS) {
@@ -149,4 +198,31 @@ public void testRGBtoDin99o() {
             assertEquals(toHexString(0xffffff & rgb), toHexString(0xffffff & din99_cielab_xyz_rgb));
         }
     }
+
+    @Test
+    public void testCIELabToDIN99bLab() {
+        ColorDin99Lab din99bLabColor = new ColorDin99Lab(61.43d, 28.64d, 11.11d);
+        ColorDin99Lab compareColor = ColorConversions.convertCIELabToDIN99bLab(ColorConversions.convertDIN99bLabToCIELab(din99bLabColor));
+        assertEquals(din99bLabColor.L99, compareColor.L99, 0.01);
+        assertEquals(din99bLabColor.a99, compareColor.a99, 0.01);
+        assertEquals(din99bLabColor.b99, compareColor.b99, 0.01);
+    }
+
+    @Test
+    public void testCIELabToDIN99oLab() {
+        ColorDin99Lab din99oLabColor = new ColorDin99Lab(54.098d, 31.237d, 28.076d);
+        ColorDin99Lab compareColor = ColorConversions.convertCIELabToDIN99oLab(ColorConversions.convertDIN99oLabToCIELab(din99oLabColor));
+        assertEquals(din99oLabColor.L99, compareColor.L99, 0.001);
+        assertEquals(din99oLabColor.a99, compareColor.a99, 0.001);
+        assertEquals(din99oLabColor.b99, compareColor.b99, 0.001);
+    }
+
+    @Test
+    public void testHunterLabtoXYZtoRGBtoXYZtoHunterLab() {
+        int greenRGB = ColorConversions.convertXYZtoRGB(ColorConversions.convertHunterLabtoXYZ(ColorHunterLab.GREEN));
+        ColorHunterLab greenHunterLab = ColorConversions.convertXYZtoHunterLab(ColorConversions.convertRGBtoXYZ(greenRGB));
+        assertEquals(ColorHunterLab.GREEN.L, greenHunterLab.L, 0.01);
+        assertEquals(ColorHunterLab.GREEN.a, greenHunterLab.a, 0.01);
+        assertEquals(ColorHunterLab.GREEN.b, greenHunterLab.b, 0.01);
+    }
 }