Compare retained image pixels without assuming SIMD color rounding

tools/chatgui/tests/test_video_frame_image.cpp

@@ -45,10 +45,11 @@ private slots:
         output[0] = image.bits();
         QCOMPARE(sws_scale(converter, source->data, source->linesize, 0, height, output, strides), height);
         for (int y = 0; y < height; y++) QCOMPARE(memcmp(image.constScanLine(y), guarded.data() + y * strides[0], width * 3), 0);
+        QColor corner = image.pixelColor(width - 1, height - 1), first = image.pixelColor(0, 0);
         QImage shared = image; image = {};
-        QCOMPARE(shared.pixelColor(width - 1, height - 1), QColor(19, 19, 19));
+        QCOMPARE(shared.pixelColor(width - 1, height - 1), corner);
         QImage detached = shared; detached.fill(Qt::red);
-        QCOMPARE(shared.pixelColor(0, 0), QColor(19, 19, 19)); QCOMPARE(detached.pixelColor(0, 0), QColor(Qt::red));
+        QCOMPARE(shared.pixelColor(0, 0), first); QCOMPARE(detached.pixelColor(0, 0), QColor(Qt::red));
     }
 };