Why is my video too bright on iPad?

discburn wrote on 7/31/2018, 3:04 AM

Trying to sort this out and hope for some help...

When I edit in VPX6, I grade on Flanders Scientific BM210 and also on Viewsonic VP2468. Both of these monitors are correctly calibrated using X-Rite equipment.

I have scopes, both in VPX and on the BM210, so everything is legal and within limits. And the picture looks nicely balanced to me.

I export to MPEG4 and open it up on iPad. It is way brighter!

As a second check, I connect the iPad by Lightning/HDMI to my Sony Bravia. It's even brighter again!

If I 'darken' the picture on my PC, it just looks 'darker' - unbalanced. I tried playing with the iPad brightness; darkening that also makes the picture look 'unbalanced'.

Maybe it's because (see attached clip) the green background in the video is just too bright and so the whole thing looks too bright when the iPad gets it. Or is there some gamma thing going on? My PC monitors are calibrated to 2.2.

Just to clarify - playing movies, YouTube, etc. looks perfect on my PC monitors, iPad and the Sony Bravia. Granted, the iPad and Sony naturally give the picture a brightness bump, but the picture is 'balanced'.

Hoping for a solution...

Seamus

Comments

johnebaker wrote on 7/31/2018, 3:22 AM

I suspect the issue is related the colour space

. . . . . My PC monitors are calibrated to 2.2 . . . .

This is equivalent to sRGB however if you exporting to a colour space other than BT.709, which is close to sRGB, then there may be brightness and/or colour shifts on various playback devices.

I would also check what colour space the iPad is set to.

HTH

John EB

discburn wrote on 7/31/2018, 4:55 AM

Hi John,

As far as my research can find out, the iPad Air 2 (my model and iPhones/iPads in general) is normally set to sRGB, so I guess videos made for it must be in Rec 709. Does Video Pro X export MPEG4 files in BT709?

Seamus

discburn wrote on 7/31/2018, 5:10 AM

Just another observation. In the following screenshot...

The Media Info file on the left is VPX6 exported video file.
The Media Info file on the right is the source video file before putting onto VPX6 timeline.

The color space for both is 'YUV'. But the source file (right) has the following information...
Color Primaries : BT .709
Transfer characteristics : BT .709
Matrix coefficients : BT .709

The output MPEG4 file (on the left) from VPX6 doesn't have that information recorded. That may mean the iPad won't read it properly because Apple requires matching to their color space in advance. IOS doesn't do conversions like, say, a PC would.

Seamus

johnebaker wrote on 7/31/2018, 5:46 AM

I cannot find out what the default export colourspace for VPX 6 is, however does it have the option on mp4 export to select the colourspace like VPX (current version) has

Looking back in one of your recent posts you were using VPX 9, which should have the option above - if you still have this what does its export of the same video look like when played on the iPad.

John EB

discburn wrote on 7/31/2018, 6:48 AM

Hi John,

No, VPX 6 doesn't have a 'Colorspace' export option. That's very interesting!

I'll try that in VPX 10, I think it is at this point.

Seamus

discburn wrote on 7/31/2018, 10:53 AM

Hi John,

Well, I opened my project (completely independently of VPX6) in VPX10 and checked the Rec 709 Colorspace for export.

The Media Info tab now adds...

Color Primaries : BT .709
Transfer characteristics : BT .709
Matrix coefficients : BT .709

But, on my iPad, it looks the same as the export from VPX6.

I'll keep researching.

Seamus

discburn wrote on 8/1/2018, 11:41 AM

Continuing this search, I've learned that videos produced within the legal range of 16-235 can be changed to 16-255 by broadcast distributors or certain devices that like to play the image back 'brighter'. I think this explains why it plays back brighter on my iPad.

But if I don't want my video changed at all, is there a way to 'lock' the output range in Video Pro X6 or Video Pro X10 so that, for example, exporting to an iPad can't brighten it? In other words, having made it to fit 16-235, a user device changing it to 16-255 won't make any difference?

johnebaker wrote on 8/1/2018, 2:13 PM

@discburn

. . . . is there a way to 'lock' the output range in Video Pro X6 or Video Pro X10 so that, for example, exporting to an iPad can't brighten it . . . .

That is not possible if you want the same video to play correctly on other devices.

Does the issue appear on other iPads?

I suspect the issue is with the iPad, depending on the model it may be related to the Auto-contrast feature which has been known to give some issues.

HTH

John EB

discburn wrote on 8/1/2018, 3:02 PM

I've checked a couple of iPads, especially the renowned iPad 3 which is the closest to Rec 709 that you can get. What I've found is that basically I like to set the brightness level quite high. So, I've set the brightness for grading my stills, and subsequently my videos, and also viewing movies at a level I think looks good. And this has become my standard. By lowering this brightness level, the iPads now look the same as my PC timeline. It's that simple!

I actually graded a clip in Davinci Resolve 12.5 and exported MPEG4 files at 'Video' and 'Data' levels. They all brighten when viewed on the iPads.

SO... I have to just set up my iPad 3 and Air 2 so that it's the same as my Viewsonic and FS BM210, which are calibrated. And get used to looking at movies and stills at a lower brightness on those devices.

Interesting note. My iPad Air 2 has a 'flaring' problem. Bright parts, like faces, if not moving for about two seconds start to 'flare', get brighter, until the person moves. Then the flare 'goes down'. It is a fault, probably in the manufacture. Doesn't happen with the iPad 3, which I will be keeping!

Thanks for you patience reading all this.

I wish every device in the world was set to the one setting! 😐

Where do I find the Auto-contrast feature?
I see there's a 'Reduce White Point' feature.

Seamus

discburn wrote on 8/1/2018, 3:21 PM

I read about the 'Auto-contrast' feature. Amazingly, that is what is causing the 'flaring' problem! So, I turned 'AssistiveTouch' On which gets rid of it. I just have to ignore the strange dot on the bottom right of the screen.

Thanks so much for putting me onto that. Now I can actually use my iPad Air 2!!

Anyway, so much for iPads!

Seamus

johnebaker wrote on 8/1/2018, 3:32 PM

@discburn

That is good news.

Happy editing

John EB

wongck wrote on 8/1/2018, 6:37 PM

Is that a iPad 2018 or iPad Pro ?

I read elsewhere in a product review that iPad Pro has a better screen and colour processor, which may help with colours and brightness. But I have no experience on this as I do not own a iPad Pro.

Sure, Auto is not always better.

discburn wrote on 8/2/2018, 12:10 AM

Mine is iPad Air 2.