Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1)
Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1)
- Subject: Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1)
- From: Lars Borg via colorsync-users <email@hidden>
- Date: Sun, 13 Feb 2022 23:30:06 +0000
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- Thread-topic: Gray Gamma 2.2 space and Photoshop2022 (23.1.1)
What???? The options are there in PS info panel, as long as you can multiply by
100.
First make sure the Gray working space, the RGB working space and the image
profile have the same gamma, such as gamma 2.2. This is because when the
readout mode is not same as the image mode, the info panel uses the working
space profile(s) to convert from image to the readout mode. Using the same
gamma on all profiles assures that gray values convert to same RGB values.
In the info panel:
- For 0-255 readout of gray and RGB images, set the readout option to 8bit RGB.
Gray 21 now read as 21,21,21. (The 8bit K readout is different, as 100% ==
black.)
- For percentage readout of gray and RGB images, set the readout option to
32-bit. Multiply by 100% as 1.0 == 100%. This works for both K and RGB readouts.
Lars, Adobe
-----Original Message-----
From: Andrew Rodney via colorsync-users <email@hidden>
Reply-To: "email@hidden" <email@hidden>
Date: Sunday, February 13, 2022 at 12:49 PM
To: "email@hidden" <email@hidden>
Subject: Re: Gray Gamma 2.2 space and Photoshop2022 (23.1.1)
On Feb 13, 2022, at 3:35 PM, Peter Miles via colorsync-users
<email@hidden> wrote:
>
> QUESTION.
> I always think of the “actual values” of greyscale files as being values from
> 0 to 255. Not a percentage, as the Photoshops eyedropper “actual values”
> report. That’s my photography background.
>
> In some situations, I want to know the actual 0-255 device values I'm sending
> in a grayscale file. Not just the device values 'reinterpreted' as a
> percentage.
> So how do you get photoshop to display the actual grayscale 0-255 values
> encoded in a grayscale file I have open.
> I can only use the RGB eyedropper display setting if I know in advance that
> my RGB “working colour space” uses the same gray-axis encoding as the
> grayscale file I have open? Or is there another way?
In Photoshop, you can view the RGB triplets as 0-255 scale (or high bit) and in
Lightroom Classic it is 0-100 percent. I wish Adobe would provide both options
in both products so we could always bounce back and forth, the don't.
Gray again is yet another scale using 0-100%. And no, there is no 0-255
option/conversion.
Maybe someone far more mathematically skilled (I'm not) can provide a simple
calculation for each.
My 'solution' is sticking with Lab which is an option in ACR/LR/PS. But again,
I sure wish Adobe would simply allow us to toggle from each scale.
Andrew Rodney
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