Improve the gamma GM significantly

Improve the gamma GM significantly

- Switch to portable typeface, to avoid per-platform diffs in the labels
- Stretch out the image slightly, to avoid overlap with larger font
- Fix several tests that were no longer matching ground-truth. We treat
  SkColor as sRGB, so 0x7F is incorrect, for example. Several of the
  XferMode tests had similar math errors now. Computed new values, and
  verified that they work as expected.
- Removed a couple tests that were mixing color and alpha in funny ways

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2288053003

Committed: https://skia.googlesource.com/skia/+/7a99a0a30194805329c5d2368dc36c61b449d0f9

[Brian Osman, 2016-08-29 20:17:20]

Description was changed from

==========
Improve the gamma GM significantly

- Switch to portable typeface, to avoid per-platform diffs in the labels
- Stretch out the image slightly, to avoid overlap with larger font
- Fix several tests that were no longer matching ground-truth. We treat
  SkColor as sRGB, so 0x7F is incorrect, for example. Several of the
  XferMode tests had similar math errors now. Computed new values, and
  verified that they work as expected.
- Removed a couple tests that were mixing color and alpha in funny ways

BUG=skia:
==========

to

==========
Improve the gamma GM significantly

- Switch to portable typeface, to avoid per-platform diffs in the labels
- Stretch out the image slightly, to avoid overlap with larger font
- Fix several tests that were no longer matching ground-truth. We treat
  SkColor as sRGB, so 0x7F is incorrect, for example. Several of the
  XferMode tests had similar math errors now. Computed new values, and
  verified that they work as expected.
- Removed a couple tests that were mixing color and alpha in funny ways

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2288053003
==========

[Brian Osman, 2016-08-29 20:17:48]

The CQ bit was checked by brianosman@google.com to run a CQ dry run

[Brian Osman, 2016-08-29 20:18:09]

brianosman@google.com changed reviewers:
+ herb@google.com, mtklein@google.com, reed@google.com

[commit-bot: I haz the power, 2016-08-29 20:18:24]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-29 20:49:27]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-29 20:49:28]

Dry run: This issue passed the CQ dry run.

[mtklein, 2016-08-30 13:43:18]

lgtm

For reference, I looked quite a bit at the gamma-correct images here:

https://gold.skia.org/search?query=source_type%3Dgm&head=true&include=true&po...

The dither reference looks wrong in Chrome and Safari on my Mac, too dark in
both.  This must be some retina-oriented upscale problem in the browser?  In any
case, the gamma correct ones look perfect to me in Preview.

[Brian Osman, 2016-08-30 13:59:00]

On 2016/08/30 13:43:18, mtklein wrote:
> lgtm
> 
> For reference, I looked quite a bit at the gamma-correct images here:
> 
>
https://gold.skia.org/search?query=source_type%3Dgm&head=true&include=true&po...
> 
> The dither reference looks wrong in Chrome and Safari on my Mac, too dark in
> both.  This must be some retina-oriented upscale problem in the browser?  In
any
> case, the gamma correct ones look perfect to me in Preview.

Yup. Our experiments have confirmed that OS-level display scaling is not gamma
correct. Appears to be true on both Mac and Windows, and even at simple (2x)
scaling. Super frustrating.

[Brian Osman, 2016-08-30 13:59:04]

The CQ bit was checked by brianosman@google.com

[commit-bot: I haz the power, 2016-08-30 13:59:16]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-30 14:08:09]

Description was changed from

==========
Improve the gamma GM significantly

- Switch to portable typeface, to avoid per-platform diffs in the labels
- Stretch out the image slightly, to avoid overlap with larger font
- Fix several tests that were no longer matching ground-truth. We treat
  SkColor as sRGB, so 0x7F is incorrect, for example. Several of the
  XferMode tests had similar math errors now. Computed new values, and
  verified that they work as expected.
- Removed a couple tests that were mixing color and alpha in funny ways

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2288053003
==========

to

==========
Improve the gamma GM significantly

- Switch to portable typeface, to avoid per-platform diffs in the labels
- Stretch out the image slightly, to avoid overlap with larger font
- Fix several tests that were no longer matching ground-truth. We treat
  SkColor as sRGB, so 0x7F is incorrect, for example. Several of the
  XferMode tests had similar math errors now. Computed new values, and
  verified that they work as expected.
- Removed a couple tests that were mixing color and alpha in funny ways

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2288053003

Committed:
https://skia.googlesource.com/skia/+/7a99a0a30194805329c5d2368dc36c61b449d0f9
==========

[commit-bot: I haz the power, 2016-08-30 14:08:10]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/7a99a0a30194805329c5d2368dc36c61b449d0f9