From 7266d8c35d073621eea4657d6c66427e3a18c4f1 Mon Sep 17 00:00:00 2001
From: Lucas CHOLLET <lucas.chollet@free.fr>
Date: Sat, 16 Dec 2023 23:28:29 -0500
Subject: [PATCH] LibGfx/TIFF: Correctly upscale samples with a resolution
 lower than 8

As pointed out by @nico, while doing a right-shift to downscale is fine,
a left-shift to upscale gives wrong results. As an example, imagine a 2-
bits value containing 3, left-shifting it would give 192 instead of 255.
---
 Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
index ec74c37594..185fb54af7 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
@@ -83,7 +83,7 @@ private:
 
         if (bits > 8)
             return value >> (bits - 8);
-        return value << (8 - bits);
+        return NumericLimits<u8>::max() * value / ((1 << bits) - 1);
     }
 
     ErrorOr<Color> read_color(BigEndianInputBitStream& stream)