Changeset 113243 in webkit

Timestamp:

Apr 4, 2012 2:48:32 PM (12 years ago)

Author:

commit-queue@webkit.org

Message:

Disable fancy upsampling and dithering for decoding jpeg on android
​https://bugs.webkit.org/show_bug.cgi?id=83196

Patch by Min Qin <​qinmin@google.com> on 2012-04-04
Reviewed by Kenneth Russell.

Dithering and fancy upsampling are currently disabled for chrome on android.
This gives us about 20% performance improvement.
Since the screen of mobile devices is small, impact on image quality is limited.
This change does not introduce any changes on other platforms.

• platform/image-decoders/jpeg/JPEGImageDecoder.cpp:

(ditherMode):
(doFancyUpsampling):
(WebCore::JPEGImageReader::decode):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/image-decoders/jpeg/JPEGImageDecoder.cpp (modified) (2 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-04-04  Min Qin  <qinmin@google.com>
+
+        Disable fancy upsampling and dithering for decoding jpeg on android
+        https://bugs.webkit.org/show_bug.cgi?id=83196
+
+        Reviewed by Kenneth Russell.
+
+        Dithering and fancy upsampling are currently disabled for chrome on android.
+        This gives us about 20% performance improvement.
+        Since the screen of mobile devices is small, impact on image quality is limited.
+        This change does not introduce any changes on other platforms.
+
+        * platform/image-decoders/jpeg/JPEGImageDecoder.cpp:
+        (ditherMode):
+        (doFancyUpsampling):
+        (WebCore::JPEGImageReader::decode):
+
 2012-04-04  Daniel Sievers  <sievers@chromium.org>
 

trunk/Source/WebCore/platform/image-decoders/jpeg/JPEGImageDecoder.cpp

@@ -84 +84 @@
 #endif
 
+#if OS(ANDROID)
+inline J_DITHER_MODE ditherMode() { return JDITHER_NONE; }
+inline bool doFancyUpsampling() { return false; }
+#else
+inline J_DITHER_MODE ditherMode() { return JDITHER_FS; }
+inline bool doFancyUpsampling() { return true; }
+#endif
+
 namespace WebCore {
 
@@ -307 +315 @@
             // of progressive JPEG.
             m_info.dct_method = dctMethod();
-            m_info.dither_mode = JDITHER_FS;
-            m_info.do_fancy_upsampling = true;
+            m_info.dither_mode = ditherMode();
+            m_info.do_fancy_upsampling = doFancyUpsampling();
             m_info.enable_2pass_quant = false;
             m_info.do_block_smoothing = true;