Fix background

lua/tokyo/utils.lua

@@ -16,8 +16,25 @@ function U.tprint(tbl, indent)
 end
 
 function U.hex2rgb(hex)
-    hex = hex:gsub("#","")
-    return tonumber("0x"..hex:sub(1,2)), tonumber("0x"..hex:sub(3,4)), tonumber("0x"..hex:sub(5,6))
+    hex = hex:gsub("#", "")
+    return tonumber("0x" .. hex:sub(1, 2)), tonumber("0x" .. hex:sub(3, 4)),
+           tonumber("0x" .. hex:sub(5, 6))
+end
+
+function U.gamma_corrector(value, gamma)
+    value = ((value / 255) ^ (1 / gamma)) * 255
+    return math.min(math.max(math.floor(value), 0), 255)
+end
+
+function U.color_gamma(hex, gamma)
+    if hex:find('#') == nil then
+        return hex
+    end
+    local r, g, b = U.hex2rgb(hex)
+    r = U.gamma_corrector(r, gamma)
+    g = U.gamma_corrector(g, gamma)
+    b = U.gamma_corrector(b, gamma)
+    return string.format("#%02x%02x%02x", r, g, b)
 end
 
 return U