diff --git a/engine/src/flutter/HACKING.md b/engine/src/flutter/HACKING.md
index b2c18c2dbf..94977af6a4 100644
--- a/engine/src/flutter/HACKING.md
+++ b/engine/src/flutter/HACKING.md
@@ -41,3 +41,27 @@ describe('My pretty test of my subject', function() {
   });
 });
 ```
+
+Adding pixel tests
+------------------
+
+Sky does not have proper pixel tests. Instead we have only reftests.
+If you want a pixel test, you need to dump the png from a reftest,
+upload it to googlestorage and then put and <img> pointing to the
+uploaded file in the reference.
+
+1. Create your test (e.g. foo.sky).
+2. Create an dummy reference file (foo-expected.sky).
+3. Run the test (it will fail).
+4. Copy the -actual.png file to googlestorage (see below).
+5. Put an <img> pointing to your newly uploaded png in the reference file.
+
+Copying the file to googlestorage:
+$ sha1sum ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png
+db0508cdfe69e996a93464050dc383f6480f1283  ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png
+$ gsutil.py cp ../out/Debug/layout-test-results/framework/flights-app-pixels-actual.png gs://mojo/sky-pngs/db0508cdfe69e996a93464050dc383f6480f1283
+
+Long-term, we should not have these tests at all and should just
+dump paint commands. In the short-term, if we find we're doing this
+a lot we should obviously automate this process, e.g. test_sky could
+do all of this work, including spitting out the correct reference file.
diff --git a/engine/src/flutter/compositor/display_delegate_bitmap.cc b/engine/src/flutter/compositor/display_delegate_bitmap.cc
index 571eda1f53..c8ba553784 100644
--- a/engine/src/flutter/compositor/display_delegate_bitmap.cc
+++ b/engine/src/flutter/compositor/display_delegate_bitmap.cc
@@ -22,7 +22,7 @@ DisplayDelegate* DisplayDelegateBitmap::create(LayerClient* client) {
 }
 
 void DisplayDelegateBitmap::GetPixelsForTesting(std::vector<unsigned char>* pixels) {
-  gfx::PNGCodec::EncodeBGRASkBitmap(bitmap_, false, pixels);
+  gfx::PNGCodec::EncodeBGRASkBitmap(bitmap_, true, pixels);
 }
 
 void DisplayDelegateBitmap::Paint(mojo::GaneshSurface& surface, const gfx::Rect& size) {