Calibrating AND profiling a phone screen

[Ivan Kolesov]

Hello Florian,

I was wondering about the default behavior in DisplayCAL when both calibrating and profiling a phone using web@localhost. In theory, if both calibration and profiling are used,  the app should apply the .cal file to the patches it sends to the browser at the profiling stage, but does it actually do that? If it does not, then, I guess, soft-calibrating a phone that way is useless, right? Thank you!

[MW]

The tone curve needs to be set to “as measured”. In your phone you will be limited to apps that can load a provided ICC file like firefox.

What phone are you using?

[Ivan Kolesov]

It’s Galaxy S7. I’m aware of the limitations in Android when it comes to color management, so I’m just converting images with cctiff, and maybe video with After Effects.

I tried skipping the calibration stage, just setting the brightness and the whitepoint in the phone settings, but then I thought, what if it can be calibrated as well as profiled. The way to do that is probably like I’ve described, applying the gamma curves to the patches sent to the browser during the profiling stage, but then again maybe DisplayCAL doesn’t do that after all, which makes the calibration step meaningless. So I’d like to know definitely what exactly DisplayCAL does in that situation.

Thanks

[MW]

So I’d like to know definitely what exactly DisplayCAL does in that situation

It tries applying a 1DLUT via the GPU to neutralize the grey scale. Since no interface exist for this on the phone its a useless step.  Set “as measured” and save your time.

More important is to set the CCSS correction. A S7 correction exist . Use it, but edit it first. Open OLEDFamily_28Aug18.ccss in a text editor and remove non-S7 data.
On the phone disable auto brightness. Also in phone settings set adaptive display screen mode to pass the full gamut.

It’s Galaxy S7

My phone before I upgraded to S20 😉

[Ivan Kolesov]

Thank you for the explanation! Sorry for the delayed answer.

I did all that except using the correction. I have an EFI ES-1000, so I thought since it’s a spectrophotometer, it can accurately measure even wide-gamut displays. Guess I was wrong. Sorry I didn’t mention the device before.

BTW, I think it’s a good idea to gamma-correct patches in web@localhost mode, since many devices nowadays have a good brightness headroom.

My phone before I upgraded to S20

I’m still keeping my fingers crossed about Android. Years ago I used to toy with Ubuntu, and even then there was a system-wide profile application tool (forgot the name), although you had to compile it. Ubuntu and Android arent’ terribly different, from what I hear.

[Vincent]

AFAIK Andorid has no ICC support or LUT3D support so in the end what you want to do is useless.

You can profile phone, “capture its behavior”, so you can predict how things look non color managed with softproof or a LUT3D or even “reencode a JPG” in phone colorspace so it looks accurate on that phone non color managed. Since this last task must be done image per image, it is only useful to create a “book” on a tablet and show your photos.

[Briunale]

Hi Ameer,

could you please have a look in all your sub-folders “inputs”, “ost”, “scripts” that there is really no folder “processor_0” existing?

Thanks,
Julie

[Ivan Kolesov]

Hi Vincent,

Thanks, I’m aware of that. I’m using Drag and Drop Robot to batch process images, and Avisynth+ and VirtualDub2 to process videos. MPV and FFMPEG didn’t work for me. I guess I just like knowing my colors are right.

[Umaiza Beck]

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