From 92a1095ca8b9cd13f233e26a5e1f70518663806e Mon Sep 17 00:00:00 2001
From: Keuin <keuinx@gmail.com>
Date: Thu, 14 Apr 2022 14:31:58 +0800
Subject: Add gamma2 correction.

---
 bitmap.h                | 17 +++++++++++++++++
 main_simple_scanner.cpp |  6 ++++++
 2 files changed, 23 insertions(+)

diff --git a/bitmap.h b/bitmap.h
index a5b05e6..58b9a25 100644
--- a/bitmap.h
+++ b/bitmap.h
@@ -71,6 +71,14 @@ struct pixel {
     static inline T max_value() {
         return mod; // FIXME
     }
+
+    inline pixel<T> gamma2() const {
+        const auto max = max_value();
+        const double r_ = sqrt(1.0 * this->r / max);
+        const double g_ = sqrt(1.0 * this->g / max);
+        const double b_ = sqrt(1.0 * this->b / max);
+        return pixel<T>::from_normalized(r_, g_, b_);
+    }
 };
 
 template<
@@ -215,6 +223,15 @@ public:
         return out;
     }
 
+    bitmap<T> gamma2() const {
+        std::vector<pixel<T>> out;
+        out.reserve(content.size());
+        for (const auto &pix: content) {
+            out.push_back(pix.gamma2());
+        }
+        return bitmap<T>{width, height, std::move(out)};
+    }
+
 };
 
 template<typename T>
diff --git a/main_simple_scanner.cpp b/main_simple_scanner.cpp
index 26518b1..91c036e 100644
--- a/main_simple_scanner.cpp
+++ b/main_simple_scanner.cpp
@@ -27,6 +27,7 @@ void generate_image(uint16_t image_width, uint16_t image_height, double viewport
     } else {
         std::cerr << "Antialiasing Samples: " << samples << std::endl;
     }
+    std::cerr << "Initializing context..." << std::endl;
     double r = 1.0 * image_width / image_height;
     viewport<T> *vp;
     if (samples == 1) {
@@ -40,10 +41,15 @@ void generate_image(uint16_t image_width, uint16_t image_height, double viewport
             100)); // the earth
     world.add_object(std::make_shared<sphere>(vec3d{0, 0, sphere_z}, sphere_r));
     timer tm;
+    std::cerr << "Rendering..." << std::endl;
     tm.start_measure();
     auto image = vp->render(world, vec3d::zero(),
                             image_width, image_height); // camera position as the coordinate origin
     tm.stop_measure();
+    std::cerr << "Applying gamma2..." << std::endl;
+    tm.start_measure();
+    image = image.gamma2(); // gamma correction
+    tm.stop_measure();
     if (!caption.empty()) {
         image.print(caption,
                     pixel<T>::from_normalized(1.0, 0.0, 0.0),
-- 
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