Multiply > divide

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffCmykScalar.cs

@@ -76,9 +76,10 @@ internal abstract partial class JpegColorConverterBase
                 }
                 else
                 {
-                    ctmp = (ctmp - ktmp) / (255F - ktmp);
-                    mtmp = (mtmp - ktmp) / (255F - ktmp);
-                    ytmp = (ytmp - ktmp) / (255F - ktmp);
+                    float divisor = 1 / (255F - ktmp);
+                    ctmp = (ctmp - ktmp) * divisor;
+                    mtmp = (mtmp - ktmp) * divisor;
+                    ytmp = (ytmp - ktmp) * divisor;
                 }
 
                 c[i] = ctmp * maxValue;

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffCmykVector128.cs

@@ -83,11 +83,11 @@ internal abstract partial class JpegColorConverterBase
                 Vector128<float> ktmp = Vector128.Min(ctmp, Vector128.Min(mtmp, ytmp));
 
                 Vector128<float> kMask = ~Vector128.Equals(ktmp, scale);
-                Vector128<float> divisor = scale - ktmp;
+                Vector128<float> divisor = Vector128<float>.One / (scale - ktmp);
 
-                ctmp = ((ctmp - ktmp) / divisor) & kMask;
-                mtmp = ((mtmp - ktmp) / divisor) & kMask;
-                ytmp = ((ytmp - ktmp) / divisor) & kMask;
+                ctmp = ((ctmp - ktmp) * divisor) & kMask;
+                mtmp = ((mtmp - ktmp) * divisor) & kMask;
+                ytmp = ((ytmp - ktmp) * divisor) & kMask;
 
                 Unsafe.Add(ref destC, i) = ctmp * scale;
                 Unsafe.Add(ref destM, i) = mtmp * scale;

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffCmykVector256.cs

@@ -83,11 +83,11 @@ internal abstract partial class JpegColorConverterBase
                 Vector256<float> ktmp = Vector256.Min(ctmp, Vector256.Min(mtmp, ytmp));
 
                 Vector256<float> kMask = ~Vector256.Equals(ktmp, scale);
-                Vector256<float> divisor = scale - ktmp;
+                Vector256<float> divisor = Vector256<float>.One / (scale - ktmp);
 
-                ctmp = ((ctmp - ktmp) / divisor) & kMask;
-                mtmp = ((mtmp - ktmp) / divisor) & kMask;
-                ytmp = ((ytmp - ktmp) / divisor) & kMask;
+                ctmp = ((ctmp - ktmp) * divisor) & kMask;
+                mtmp = ((mtmp - ktmp) * divisor) & kMask;
+                ytmp = ((ytmp - ktmp) * divisor) & kMask;
 
                 Unsafe.Add(ref destC, i) = ctmp * scale;
                 Unsafe.Add(ref destM, i) = mtmp * scale;

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffCmykVector512.cs

@@ -92,11 +92,11 @@ internal abstract partial class JpegColorConverterBase
                 Vector512<float> ktmp = Vector512.Min(ctmp, Vector512.Min(mtmp, ytmp));
 
                 Vector512<float> kMask = ~Vector512.Equals(ktmp, scale);
-                Vector512<float> divisor = scale - ktmp;
+                Vector512<float> divisor = Vector512<float>.One / (scale - ktmp);
 
-                ctmp = ((ctmp - ktmp) / divisor) & kMask;
-                mtmp = ((mtmp - ktmp) / divisor) & kMask;
-                ytmp = ((ytmp - ktmp) / divisor) & kMask;
+                ctmp = ((ctmp - ktmp) * divisor) & kMask;
+                mtmp = ((mtmp - ktmp) * divisor) & kMask;
+                ytmp = ((ytmp - ktmp) * divisor) & kMask;
 
                 Unsafe.Add(ref destC, i) = ctmp * scale;
                 Unsafe.Add(ref destM, i) = mtmp * scale;

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffYccKScalar.cs

@@ -75,9 +75,10 @@ internal abstract partial class JpegColorConverterBase
             for (int i = 0; i < cr.Length; i++)
             {
                 // Scale down to [0-1]
-                float r = rLane[i] / 255F;
-                float g = gLane[i] / 255F;
-                float b = bLane[i] / 255F;
+                const float divisor = 1F / 255F;
+                float r = rLane[i] * divisor;
+                float g = gLane[i] * divisor;
+                float b = bLane[i] * divisor;
 
                 float ytmp;
                 float cbtmp;
@@ -87,15 +88,16 @@ internal abstract partial class JpegColorConverterBase
                 if (ktmp >= 1F)
                 {
                     ytmp = 0F;
-                    cbtmp = 0F;
-                    crtmp = 0F;
+                    cbtmp = 0.5F;
+                    crtmp = 0.5F;
                     ktmp = maxValue;
                 }
                 else
                 {
-                    r /= 1F - ktmp;
-                    g /= 1F - ktmp;
-                    b /= 1F - ktmp;
+                    float kmask = 1F / (1F - ktmp);
+                    r *= kmask;
+                    g *= kmask;
+                    b *= kmask;
 
                     // Scale to [0-maxValue]
                     ytmp = ((0.299f * r) + (0.587f * g) + (0.114f * b)) * maxValue;

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffYccKVector128.cs

@@ -86,7 +86,7 @@ internal abstract partial class JpegColorConverterBase
             ref Vector128<float> destK =
                 ref Unsafe.As<float, Vector128<float>>(ref MemoryMarshal.GetReference(values.Component3));
 
-            Vector128<float> maxSourceValue = Vector128.Create(255F);
+            Vector128<float> maxSourceValue = Vector128.Create(1 / 255F);
             Vector128<float> maxSampleValue = Vector128.Create(this.MaximumValue);
             Vector128<float> chromaOffset = Vector128.Create(this.HalfValue);
 
@@ -102,17 +102,17 @@ internal abstract partial class JpegColorConverterBase
             nuint n = values.Component0.Vector128Count<float>();
             for (nuint i = 0; i < n; i++)
             {
-                Vector128<float> r = Unsafe.Add(ref srcR, i) / maxSourceValue;
-                Vector128<float> g = Unsafe.Add(ref srcG, i) / maxSourceValue;
-                Vector128<float> b = Unsafe.Add(ref srcB, i) / maxSourceValue;
+                Vector128<float> r = Unsafe.Add(ref srcR, i) * maxSourceValue;
+                Vector128<float> g = Unsafe.Add(ref srcG, i) * maxSourceValue;
+                Vector128<float> b = Unsafe.Add(ref srcB, i) * maxSourceValue;
                 Vector128<float> ktmp = Vector128<float>.One - Vector128.Max(r, Vector128.Min(g, b));
 
                 Vector128<float> kMask = ~Vector128.Equals(ktmp, Vector128<float>.One);
-                Vector128<float> divisor = Vector128<float>.One - ktmp;
+                Vector128<float> divisor = Vector128<float>.One / (Vector128<float>.One - ktmp);
 
-                r /= divisor;
-                g /= divisor;
-                b /= divisor;
+                r = (r * divisor) & kMask;
+                g = (g * divisor) & kMask;
+                b = (b * divisor) & kMask;
 
                 // y  =   0 + (0.299 * r) + (0.587 * g) + (0.114 * b)
                 // cb = 128 - (0.168736 * r) - (0.331264 * g) + (0.5 * b)

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffYccKVector256.cs

@@ -108,11 +108,11 @@ internal abstract partial class JpegColorConverterBase
                 Vector256<float> ktmp = Vector256<float>.One - Vector256.Max(r, Vector256.Min(g, b));
 
                 Vector256<float> kMask = ~Vector256.Equals(ktmp, Vector256<float>.One);
-                Vector256<float> divisor = Vector256<float>.One - ktmp;
+                Vector256<float> divisor = Vector256<float>.One / (Vector256<float>.One - ktmp);
 
-                r /= divisor;
-                g /= divisor;
-                b /= divisor;
+                r = (r * divisor) & kMask;
+                g = (g * divisor) & kMask;
+                b = (b * divisor) & kMask;
 
                 // y  =   0 + (0.299 * r) + (0.587 * g) + (0.114 * b)
                 // cb = 128 - (0.168736 * r) - (0.331264 * g) + (0.5 * b)

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffYccKVector512.cs

@@ -119,11 +119,11 @@ internal abstract partial class JpegColorConverterBase
                 Vector512<float> ktmp = Vector512<float>.One - Vector512.Max(r, Vector512.Min(g, b));
 
                 Vector512<float> kMask = ~Vector512.Equals(ktmp, Vector512<float>.One);
-                Vector512<float> divisor = Vector512<float>.One - ktmp;
+                Vector512<float> divisor = Vector512<float>.One / (Vector512<float>.One - ktmp);
 
-                r /= divisor;
-                g /= divisor;
-                b /= divisor;
+                r = (r * divisor) & kMask;
+                g = (g * divisor) & kMask;
+                b = (b * divisor) & kMask;
 
                 // y  =   0 + (0.299 * r) + (0.587 * g) + (0.114 * b)
                 // cb = 128 - (0.168736 * r) - (0.331264 * g) + (0.5 * b)

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.YccKVector512.cs

@@ -138,6 +138,6 @@ internal abstract partial class JpegColorConverterBase
 
         /// <inheritdoc/>
         protected override void ConvertFromRgbScalarRemainder(in ComponentValues values, Span<float> rLane, Span<float> gLane, Span<float> bLane)
-            => TiffYccKScalar.ConvertFromRgb(in values, this.HalfValue, this.MaximumValue, rLane, gLane, bLane);
+            => YccKScalar.ConvertFromRgb(in values, this.HalfValue, this.MaximumValue, rLane, gLane, bLane);
     }
 }