color: remove brightness related stuff

src/color.zig

@@ -608,80 +608,3 @@ test "100 random colors" {
         try expectEqualDeep(rgb, rgb_from_lab);
     }
 }
-
-export fn computeBrightnessRgba(image: [*]const Rgba, rows: usize, cols: usize) f32 {
-    const size = rows * cols;
-    const img = image[0..size];
-    var r_sum: u64 = 0;
-    var g_sum: u64 = 0;
-    var b_sum: u64 = 0;
-    for (img) |p| {
-        r_sum += p.r;
-        g_sum += p.g;
-        b_sum += p.b;
-    }
-    return (@as(f32, @floatFromInt(r_sum)) * 0.2 +
-        @as(f32, @floatFromInt(g_sum)) * 0.7 +
-        @as(f32, @floatFromInt(b_sum)) * 0.1) /
-        @as(f32, @floatFromInt(size));
-}
-
-export fn computeBrightnessSimd(image: [*]const u8, size: usize) f32 {
-    const vector_len: usize = 512;
-    const pixel_len: usize = 4;
-    const repeat: usize = vector_len / pixel_len;
-    const img = image[0..size];
-    const r_idx: @Vector(vector_len, usize) = [_]usize{ 1, 0, 0, 0 } ** repeat;
-    const g_idx: @Vector(vector_len, usize) = [_]usize{ 0, 1, 0, 0 } ** repeat;
-    const b_idx: @Vector(vector_len, usize) = [_]usize{ 0, 0, 1, 0 } ** repeat;
-    var r_sum: u64 = 0;
-    var g_sum: u64 = 0;
-    var b_sum: u64 = 0;
-    var pos: usize = 0;
-    var rem = size;
-    var tmp: @Vector(vector_len, usize) = undefined;
-    while (rem > 0) {
-        if (rem < vector_len) {
-            while (pos < img.len) {
-                r_sum += img[pos];
-                g_sum += img[pos + 1];
-                b_sum += img[pos + 2];
-                pos += pixel_len;
-                rem -= pixel_len;
-            }
-        } else {
-            const v: @Vector(vector_len, u8) = img[pos..][0..vector_len].*;
-            tmp = r_idx * v;
-            r_sum += @reduce(.Add, tmp);
-            tmp = g_idx * v;
-            g_sum += @reduce(.Add, tmp);
-            tmp = b_idx * v;
-            b_sum += @reduce(.Add, tmp);
-            pos += vector_len;
-            rem -= vector_len;
-        }
-    }
-    return (@as(f32, @floatFromInt(r_sum)) * 0.2 +
-        @as(f32, @floatFromInt(g_sum)) * 0.7 +
-        @as(f32, @floatFromInt(b_sum)) * 0.1) /
-        @as(f32, @floatFromInt(size / pixel_len));
-}
-
-test "brightness" {
-    const rows: usize = 4321;
-    const cols: usize = 987;
-    const pixel_len = 4;
-    const size = rows * cols * pixel_len;
-    var img = [_]u8{1} ** size;
-    try std.testing.expectEqual(computeBrightnessRgba(@alignCast(@ptrCast(img[0..].ptr)), rows, cols), 1);
-    const seed: u64 = @truncate(@as(u128, @bitCast(std.time.nanoTimestamp())));
-    var prng = std.Random.DefaultPrng.init(seed);
-    var random = prng.random();
-    for (&img) |*p| {
-        p.* = random.int(u8);
-    }
-    try std.testing.expectEqual(
-        computeBrightnessRgba(@alignCast(@ptrCast(img[0..].ptr)), rows, cols),
-        computeBrightnessSimd(img[0..size].ptr, size),
-    );
-}