Enable screen detection mode 2 for image-focused tunings

Enable screen detection mode 2: anti-aliased text and graphics aware
for AOM_TUNE_IQ and AOM_TUNE_SSIMULACRA2.

Doing so can improve screen content coding efficiency (not detected
as such by mode 1) by up to 50%.

Bug: aomedia:401234702
Change-Id: I5f652c92458abef81a8dbb79a35f04638d01e43a

aom/aomcx.h

diff --git a/aom/aomcx.h b/aom/aomcx.h
index dd97511..d40f000 100644
--- a/aom/aomcx.h
+++ b/aom/aomcx.h
@@ -1729,6 +1729,7 @@
  *   * --enable-cdef=3
  *   * --enable-chroma-deltaq=1
  *   * --deltaq-mode=6
+ *   * --screen-detection-mode=2
  * AOM_TUNE_IQ additionally sets the following options:
  *   * --enable-adaptive-sharpness=1
  */

av1/av1_cx_iface.c

diff --git a/av1/av1_cx_iface.c b/av1/av1_cx_iface.c
index 6f8651b..8b44cf5 100644
--- a/av1/av1_cx_iface.c
+++ b/av1/av1_cx_iface.c
@@ -1870,6 +1870,8 @@
     extra_cfg->enable_chroma_deltaq = 1;
     // Enable "Variance Boost" deltaq mode, optimized for images.
     extra_cfg->deltaq_mode = DELTA_Q_VARIANCE_BOOST;
+    // Enable "anti-aliased text and graphics aware" screen detection mode.
+    extra_cfg->screen_detection_mode = AOM_SCREEN_DETECTION_ANTIALIASING_AWARE;
   }
   if (extra_cfg->tuning == AOM_TUNE_IQ) {
     // Enable adaptive sharpness to adjust loop filter levels according to QP.