From 1169bed9a58581c8afccbe8709f4563d2b3604cd Mon Sep 17 00:00:00 2001
From: Pierre-Yves Nicolas <6371790+pynicolas@users.noreply.github.com>
Date: Tue, 21 Apr 2026 15:38:45 +0200
Subject: [PATCH] Grayscale: avoid darkening pages with little content (#158)

Adjust black point: 0.01 -> 0.004
---
 .../main/java/org/fairscan/imageprocessing/PostProcessing.kt    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/imageprocessing/src/main/java/org/fairscan/imageprocessing/PostProcessing.kt b/imageprocessing/src/main/java/org/fairscan/imageprocessing/PostProcessing.kt
index 9bb3eb0..4dc52d3 100644
--- a/imageprocessing/src/main/java/org/fairscan/imageprocessing/PostProcessing.kt
+++ b/imageprocessing/src/main/java/org/fairscan/imageprocessing/PostProcessing.kt
@@ -253,7 +253,7 @@ fun enhanceGrayscaleImage(img: Mat): Mat {
     val sorted = Mat()
     Core.sort(flat, sorted, Core.SORT_ASCENDING)
     val n = sorted.cols()
-    val pLow  = sorted.get(0, (n * 0.01).toInt())[0]
+    val pLow  = sorted.get(0, (n * 0.004).toInt())[0]
     val pHigh = sorted.get(0, (n * 0.99).toInt())[0]
     flat.release(); sorted.release()