1 files changed, 73 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/modular/transform/enc_rct.cc b/third_party/jpeg-xl/lib/jxl/modular/transform/enc_rct.cc
new file mode 100644
index 0000000000..050563a3c2
--- /dev/null
+++ b/third_party/jpeg-xl/lib/jxl/modular/transform/enc_rct.cc
@@ -0,0 +1,73 @@
+// Copyright (c) the JPEG XL Project Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "lib/jxl/modular/transform/enc_rct.h"
+
+#include "lib/jxl/base/status.h"
+#include "lib/jxl/common.h"
+#include "lib/jxl/modular/modular_image.h"
+#include "lib/jxl/modular/transform/transform.h"  // CheckEqualChannels
+
+namespace jxl {
+
+Status FwdRCT(Image& input, size_t begin_c, size_t rct_type, ThreadPool* pool) {
+  JXL_RETURN_IF_ERROR(CheckEqualChannels(input, begin_c, begin_c + 2));
+  if (rct_type == 0) {  // noop
+    return false;
+  }
+  // Permutation: 0=RGB, 1=GBR, 2=BRG, 3=RBG, 4=GRB, 5=BGR
+  int permutation = rct_type / 7;
+  // 0-5 values have the low bit corresponding to Third and the high bits
+  // corresponding to Second. 6 corresponds to YCoCg.
+  //
+  // Second: 0=nop, 1=SubtractFirst, 2=SubtractAvgFirstThird
+  //
+  // Third: 0=nop, 1=SubtractFirst
+  int custom = rct_type % 7;
+  size_t m = begin_c;
+  size_t w = input.channel[m + 0].w;
+  size_t h = input.channel[m + 0].h;
+  int second = (custom % 7) >> 1;
+  int third = (custom % 7) & 1;
+  const auto do_rct = [&](const int y, const int thread) {
+    const pixel_type* in0 = input.channel[m + (permutation % 3)].Row(y);
+    const pixel_type* in1 =
+        input.channel[m + ((permutation + 1 + permutation / 3) % 3)].Row(y);
+    const pixel_type* in2 =
+        input.channel[m + ((permutation + 2 - permutation / 3) % 3)].Row(y);
+    pixel_type* out0 = input.channel[m].Row(y);
+    pixel_type* out1 = input.channel[m + 1].Row(y);
+    pixel_type* out2 = input.channel[m + 2].Row(y);
+    if (custom == 6) {
+      for (size_t x = 0; x < w; x++) {
+        pixel_type R = in0[x];
+        pixel_type G = in1[x];
+        pixel_type B = in2[x];
+        out1[x] = R - B;
+        pixel_type tmp = B + (out1[x] >> 1);
+        out2[x] = G - tmp;
+        out0[x] = tmp + (out2[x] >> 1);
+      }
+    } else {
+      for (size_t x = 0; x < w; x++) {
+        pixel_type First = in0[x];
+        pixel_type Second = in1[x];
+        pixel_type Third = in2[x];
+        if (second == 1) {
+          Second = Second - First;
+        } else if (second == 2) {
+          Second = Second - ((First + Third) >> 1);
+        }
+        if (third) Third = Third - First;
+        out0[x] = First;
+        out1[x] = Second;
+        out2[x] = Third;
+      }
+    }
+  };
+  return RunOnPool(pool, 0, h, ThreadPool::NoInit, do_rct, "FwdRCT");
+}
+
+}  // namespace jxl