P: “Viewer Gamma” Settings Affect Exported Video

[Guillaume30883528kcuh]

"viewer gamma" settings dont act the same wether a clip color space is unchanged or not

• Adobe Premiere Pro version number: 25.1.0 (build 73)
• Operating system : macOS sequoia 15.3.1
• System Info:
  

  • Apple M2 MacBook air

  • 3,5 GHz apple GPU 10

  • 16Go DDR5 RAM

  • Hard Drive 1To

• Video format: any image media
• Workflow details: any project, any sequence
• Steps to reproduce - (Very important!)
  

  I'm french so excuse my english please.

  Place any image media clip with rec709 2.4 profile (video, png, jpg...) on a timeline (any settings)

  select the clip
  In the lumetri color settings panel :
  Display color management is on

  working color space : rec709

  Set the "source clip" section on "use media color space" (so rec709)

  "viewer gamma" on 2.4

  export the clip as an h264 file (any settings) this is FILE 1A
  change "viewer gamma" to 1.96
  then Image should look different inside Premiere's program monitor
  export the clip as an h264 file (any settings) this is FILE 1B
  
  Now Set the "source clip" section on "override Media Color Space" and select sRGB (for instance)Same pattern of export :
  Set "viewer gamma" to 2.4
  export the clip as an h264 file (any settings) this is FILE 2A
  Set "viewer gamma" to 1.96
  This time image should not undergo any change of look inside Premiere program monitor
  export the clip as an h264 file (any settings) this is FILE 2B
  
• Expected result - "viewer gamma" should not change the actual gamma correction of exported files even if we override some media color spaces, since it seems meant to be a monitoring setting. HOWEVER, it woulb be very nice to be able to apply a gamma correction on a timeline (wich would apply on exportted files)
• Actual resul
  FILE 1A and FILE 1B look the same, same luminance, even with different viewer gamma set in Premiere
  FILE 2A and FILE 2B look differents, shift of luminance, because of different viewer gamma set in Premiere
  

  SUMMARY :Viewer gamma set on 2.4 or 1.96 change the look of images inside premiere's display but does not affect the exported file.

  EXCEPT

  if for some reason we want to override media color space of the clip (here set to sRGB instead of rec709) then we get in the reverse situation : changing "viewer gamma" from 2.4 to 1.96 won't do anything in premiere display, but the exported files will be different.

  It seems like overriding color space of the media is applied after the gamma viewer correction, wich is very weird logic to me.

  Am I missing something ?

[Kevin-Monahan]

Hi @Guillaume30883528kcuh,

Thanks for the post and welcome to the forum. I am Kevin from Support, a mod here. I appreciate you filing the bug report and providing all the details here. I hope the team will answer you shortly. Sorry for the problem.

Thanks,
Kevin

[jamieclarke]

Hi @Guillaume30883528kcuh -   We are aware of this issue. When using the Auto Detect Log Video feature and tonemapping to Rec. 709, a gamma shift may occur when exporting with "Viewer Gamma" set to 1.96, 2.2, or 2.4, with the most noticeable shift occurring at 2.2. As a workaround, set “Viewer Gamma” to 1.96 or 2.4 before exporting.

[Guillaume30883528kcuh]

Hi Jamie

I didnt notice the big shift at 2.2.

The problem with my kind of edits is that its mixing different sources of medias with multiple color spaces. So when setting the viewer gamma to 1.96 (in order to export preview for  my clients who are macOS users), some clips would keep the look I see in Premiere and some others wont (those with color space override).

Thanks for your answer though, I hope it would be fix soon because its a very tough issue for color managing

[Ckun]

お世話になります。日本語での投稿にて失礼致します。

ビューアガンマの設定は、ビューアの表示のみに影響するものだと思います。

しかし、シーケンスの出力カラースペースと異なるカラースペースのクリップを使用すると、ビューアガンマの設定が出力に影響します。

再現の手順

1. Rec. 709のシーケンスを作成します。
2. Rec. 709のクリップと、それ以外のカラースペースを持つクリップ（HLGの動画やsRGBの静止画など）をシーケンスに載せて、左右に並べます。
3. ビューアガンマの設定を変更すると、Rec. 709ではない方のクリップのトーンが変化します。

期待される結果は、ビューアガンマの設定値は出力される映像に影響を及ばさず、ビューアの表示のみに適切に反映される状態です。

検証に使用した環境はこちらです。

MacBook Pro 13-inch, M1, 2020, macOS 15.4.1, Premiere Pro v25.2.1

再現テストの様子の動画ファイルを添付します。

Prec. 709のシーケンス上で、左にRec.709のクリップ、右にHLGのクリップを配置しています。ビューアガンマの設定を変更すると、Lumetriスコープの動きから分かる通り、右のHLGのクリップのトーンが変化してしまいます。

なお、Lumetriスコープにて、RAMP信号からトーンの変化が読み取りやすいよう、意図的に入力トーンマッピングはOFFにしております。

この現象は意図しないものではないかと思うのですが、いかがでしょうか。

よろしくお願いいたします。

[R Neil Haugen]

The viewer gamma sets the Program monitor's internal display transform for gamma 1.96, 2.2, or 2.4 at your choice.

I can't be sure, but it looks like you're using the Program monitor, and what little I can tell of your provided clip, the whole image looks like it is changing. As it should.

Because it sets the Program Monitor's display gamma ... period. The Program monitor cannot show two different color spaces at the same time. It is one or the other.

[jamieclarke]

HI @Ckun - This is something the team is aware of.  I'm going to merge this with the primary thread.

[Ckun]

Hi jamieclarke

Thank you for answering my question.
I hope this issue will be resolved soon.

[Guillaume30883528kcuh]

Hi @R Neil Haugen 

I know it should set "the program monitor gamma.... period"

But sometimes it doesn't.

This is the very point of this topic actually

[R Neil Haugen]

I haven't been able to replicate this. It shouldn't be an issue, and it's good to hear they are checking into why it happens some times.

[gianniw27226249]

I’ve got another problem: one video was exported using Viewer Gamma Web, and the other with Viewer Gamma QuickTime — but despite that, the black levels in both videos look exactly the same when viewed in QuickTime. In the past, it was ALWAYS the case that I could use this method to correct that annoying gamma shift, depending on which platform I was rendering for.

[R Neil Haugen]

First, understand that no two screens will ever show the same image ... even two "identical" monitors, heavily calibrated, sitting side-by-side fed an identical image from a Decklink card. As has been demonstrated time and again. By the time you allow for every panel being slightly different at manufacturing, the differences in hardware built around that panel, the firmware involved, the different operating systems and setups and all of the playback device, it's totally bonkers what any one screen will actually show.

And pro colorists (yes, I teach same) are taught no one will ever, in any delivery process, see the same image you do.

There isn't any "everyone gonna see exactly this" possible. Ok, now that we have that truth stated, let's get to your post.

The viewer gamma is not applied to the file at export ... as no gamma is applied at export. Changing viewing gamma only changes the gamma used within Premiere's program monitor in sending the image to the screen in Premiere. So after changing viewing gamma, did you re-correct the image in Premiere before export? As if you didn't, of course nothing in the image file would be different.

Changing viewer gamma only changes the view of the image, in Premiere, as it changes the gamma used to display the image. You then need to modify the image color/tonal corrections after setting viewing gamma. That is what gets exported ... the file as newly corrected.

If Apple had simply followed proper, long-established/published standards for Rec.709-Bt.1886 video display in ColorSync, we wouldn't have this mess.

Qt Player, on Macs without Reference modes with that set to HDTV, will use essentially gamma 1.96 to display SDR video. The standard is supposed to be gamma 2.4, which actually, VLC and Potplayer will use on those Macs.

Macs with Reference modes set to HDTV, and virtually all other screens PC/broadcast-compliant/Android/TVs ... will use the gamma 2.4 of the expected standard.

And "web is 2.2" ... yes, for stills with the sRGB color space. Nearly all monitors/devices will use the 2.4 for Rec.709 video files.

[Dani_V.]

Hi @gianniw27226249,

Sorry you are experiencing issues. The team is aware of a gamma shift occurring in exports when using the Auto Detect Log Video feature and tone-mapping to Rec. 709. Will merge your post with the main thread regarding this problem.

Sorry for the frustration,

Dani