From 04e59ad2c819ee7213b0ae2efb2d14ddca827cd0 Mon Sep 17 00:00:00 2001
From: boatbomber <arbitrarysoandso@gmail.com>
Date: Fri, 12 Nov 2021 02:02:30 -0500
Subject: [PATCH] Dynamic lossy combined with CIE76 deltaE

---
 src/GuiPool.lua |  2 +-
 src/Util.lua    | 88 ++++++++++++++++++++++++++++++++++++++++++++-----
 src/init.lua    | 11 +++----
 3 files changed, 86 insertions(+), 15 deletions(-)

diff --git a/src/GuiPool.lua b/src/GuiPool.lua
index 4408295..237eb17 100644
--- a/src/GuiPool.lua
+++ b/src/GuiPool.lua
@@ -1,6 +1,6 @@
 local module = {}
 
-local OFF_SCREEN = UDim2.fromOffset(0,3000)
+local OFF_SCREEN = UDim2.fromOffset(0, 3000)
 
 function module.new(original: GuiObject, initSize: number?)
 	local Pool = {
diff --git a/src/Util.lua b/src/Util.lua
index 8c036e5..f787430 100644
--- a/src/Util.lua
+++ b/src/Util.lua
@@ -1,14 +1,86 @@
 local Util = {}
 
+-- D65/2°
+local Xr = 95.047
+local Yr = 100.0
+local Zr = 108.883
+local labCache = {}
+function Util.RGBtoLAB(c)
+	if labCache[c] then
+		return table.unpack(labCache[c])
+	end
+
+	local X, Y, Z
+	do -- Convert RGB to XYZ
+		local r, g, b = c.R, c.G, c.B
+
+		if r > 0.04045 then
+			r = ((r + 0.055) / 1.055) ^ 2.4
+		else
+			r /= 12.92
+		end
+
+		if g > 0.04045 then
+			g = ((g + 0.055) / 1.055) ^ 2.4
+		else
+			g /= 12.92
+		end
+
+		if b > 0.04045 then
+			b = ((b + 0.055) / 1.055) ^ 2.4
+		else
+			b /= 12.92
+		end
+
+		r *= 100
+		g *= 100
+		b *= 100
+
+		X = 0.4124 * r + 0.3576 * g + 0.1805 * b
+		Y = 0.2126 * r + 0.7152 * g + 0.0722 * b
+		Z = 0.0193 * r + 0.1192 * g + 0.9505 * b
+	end
+
+	local l, a, b
+	do -- Convert XYZ to LAB
+		local xr, yr, zr = X / Xr, Y / Yr, Z / Zr
+
+		if xr > 0.008856 then
+			xr = xr ^ (1 / 3)
+		else
+			xr = ((7.787 * xr) + 16 / 116.0)
+		end
+
+		if yr > 0.008856 then
+			yr = yr ^ (1 / 3)
+		else
+			yr = ((7.787 * yr) + 16 / 116.0)
+		end
+
+		if zr > 0.008856 then
+			zr = zr ^ (1 / 3)
+		else
+			zr = ((7.787 * zr) + 16 / 116.0)
+		end
+
+		l, a, b = (116 * yr) - 16, 500 * (xr - yr), 200 * (yr - zr)
+	end
+
+	labCache[c] = { l, a, b }
+
+	return l, a, b
+end
+
 function Util.DeltaRGB(a: Color3, b: Color3)
-	local r1, g1, b1 = a.R,a.G,a.B
-	local r2, g2, b2 = b.R,b.G,b.B
-	local drp2 = (r1 - r2)^2
-	local dgp2 = (g1 - g2)^2
-	local dbp2 = (b1 - b2)^2
-	local t = (r1 + r2) / 2
-
-	return math.sqrt(2 * drp2 + 4 * dgp2 + 3 * dbp2 + t * (drp2 - dbp2) / 256) / 3
+	local l1, a1, b1 = Util.RGBtoLAB(a)
+	local l2, a2, b2 = Util.RGBtoLAB(b)
+
+	local delta = math.sqrt((l2 - l1) ^ 2 + (a2 - a1) ^ 2 + (b2 - b1) ^ 2)
+	if delta < 30 then
+		return 0.03
+	else
+		return delta / 200
+	end
 end
 
 return Util
diff --git a/src/init.lua b/src/init.lua
index a2c184e..ac4735e 100644
--- a/src/init.lua
+++ b/src/init.lua
@@ -3,8 +3,6 @@ local module = {}
 local GuiPool = require(script.GuiPool)
 local Util = require(script.Util)
 
-local LOSSY = 0.03 -- Use fewer Frames at cost of image accuracy (Some values get funky, tweak carefully)
-
 local EMPTY_TABLE = {}
 
 function module.new(ResX: number, ResY: number)
@@ -15,6 +13,8 @@ function module.new(ResX: number, ResY: number)
 	}
 
 	local invX, invY = 1 / ResX, 1 / ResY
+	local diff = 0.015
+	local lossy = math.clamp(diff + ResY / 250, 0.02, 1)
 
 	-- Generate initial grid of color data
 	local Grid = table.create(ResX)
@@ -73,7 +73,7 @@ function module.new(ResX: number, ResY: number)
 		Frame.Parent = Container
 
 		if Canvas._ColumnFrames[x] == nil then
-			Canvas._ColumnFrames[x] = {Frame}
+			Canvas._ColumnFrames[x] = { Frame }
 		else
 			table.insert(Canvas._ColumnFrames[x], Frame)
 		end
@@ -114,7 +114,6 @@ function module.new(ResX: number, ResY: number)
 			self._ActiveFrames = 0
 			table.clear(self._ColumnFrames)
 		end
-
 	end
 
 	function Canvas:Render()
@@ -132,10 +131,10 @@ function module.new(ResX: number, ResY: number)
 			for y, Color in ipairs(Column) do
 				pixelCount += 1
 				local delta = Util.DeltaRGB(lastColor, Color)
-				if delta > 0.015 then
+				if delta > diff then
 					local offset = y - pixelStart - 1
 
-					if delta > 0.015+LOSSY then
+					if delta > lossy then
 						table.insert(Compressed, { p = offset - 0.02, c = lastColor })
 					end
 					table.insert(Compressed, { p = offset, c = Color })