From fd3d6fa3a1048418c1a2bfde68ca4478afad038d Mon Sep 17 00:00:00 2001
From: Marek Ossowski <marek0ossowski@gmail.com>
Date: Sun, 17 Aug 2025 00:36:21 +0200
Subject: [PATCH] Fixed accumulating of image rows

---
 app/src/main/java/xdsopl/robot36/HFFax.java | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/xdsopl/robot36/HFFax.java b/app/src/main/java/xdsopl/robot36/HFFax.java
index 1534ad2..a418861 100644
--- a/app/src/main/java/xdsopl/robot36/HFFax.java
+++ b/app/src/main/java/xdsopl/robot36/HFFax.java
@@ -104,8 +104,9 @@ public class HFFax extends BaseMode {
             int color = ColorConverter.GRAY(scratchBuffer[position]);
             pixelBuffer.pixels[i] = color;
 
-            cumulated[i] *= 0.99f; //decay old data
-            cumulated[i] += Color.luminance(color);
+            //accumulate recent values, forget old
+            float decay = 0.99f;
+            cumulated[i] = cumulated[i] * decay + Color.luminance(color) * (1 - decay);
         }
 
         //try to detect "sync": thick white margin