High precision color picker

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High precision color picker

Elliott Balsley
Hello.  I am trying to create technical test patterns, so I would like to
specify colors by entering 16-bit RGB values.  Is this possible in Gimp?  I
just installed it for the first time and it looks like the color picker is
limited to 8-bit values 0-255.  Photoshop is also limited in this way,
which is why I am trying other apps.
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Re: High precision color picker

Ofnuts-2
In Gimp the color selector can be use with a 0-255 integer range or as
percent (3 digits: 12.3%) that give a bit more precision.

In scripts there is not limit to the precision of the color you enter as
floating point (but widgets that will display the values will round it).
For instance in Python:

import gimpcolor
pdb.gimp_context_set_foreground(gimpcolor.RGB(.51256,.51257,.51258))

Of course this is only useful in high-precision image, and there is no
guarantee that the underlying computations use all the precision, but
also no good reason to not do so.


On 1/9/20 1:11 AM, Elliott Balsley wrote:

> Hello.  I am trying to create technical test patterns, so I would like to
> specify colors by entering 16-bit RGB values.  Is this possible in Gimp?  I
> just installed it for the first time and it looks like the color picker is
> limited to 8-bit values 0-255.  Photoshop is also limited in this way,
> which is why I am trying other apps.
> _______________________________________________
> gimp-user-list mailing list
> List address:    [hidden email]
> List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list
> List archives:   https://mail.gnome.org/archives/gimp-user-list


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Re: High precision color picker

Users mailing list
On Thu, Jan 9, 2020 at 3:45 AM Ofnuts wrote:
>
> In Gimp the color selector can be use with a 0-255 integer range or as
> percent (3 digits: 12.3%) that give a bit more precision.

I would strongly advise using the Pixel option instead. It gives
exactly the precision of the actual pixel data.

So if the image is 16-bit float, this will yield
(0,014557;0,053680;0,827148) for what is (32;66;235) in RGB. That
should be precise enough :)

Alex
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Re: High precision color picker

Elliott Balsley
In reply to this post by Elliott Balsley
>
> On Thu, Jan 9, 2020 at 3:45 AM Ofnuts wrote:
> I would strongly advise using the Pixel option instead. It gives
> exactly the precision of the actual pixel data.
>
> So if the image is 16-bit float, this will yield
> (0,014557;0,053680;0,827148) for what is (32;66;235) in RGB. That
> should be precise enough :)
>

Hi.  This sounds promising. Can you please explain what you mean by "the
pixel option" ?  How can I enter values like this?  I would actually prefer
16-bit integer, but float could work too.
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Re: High precision color picker

Paul St George
In reply to this post by Elliott Balsley

On 10/01/2020 12:00, [hidden email] wrote:

>> On Thu, Jan 9, 2020 at 3:45 AM Ofnuts wrote:
>> I would strongly advise using the Pixel option instead. It gives
>> exactly the precision of the actual pixel data.
>>
>> So if the image is 16-bit float, this will yield
>> (0,014557;0,053680;0,827148) for what is (32;66;235) in RGB. That
>> should be precise enough:)
>>
> Hi.  This sounds promising. Can you please explain what you mean by "the
> pixel option" ?  How can I enter values like this?  I would actually prefer
> 16-bit integer, but float could work too.

I would also like to know more about the Pixel option! Sounds very
interesting.

Thanks.


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Re: High precision color picker

Users mailing list
In reply to this post by Elliott Balsley
On Thu, Jan 9, 2020 at 9:23 PM Elliott Balsley wrote:

> > I would strongly advise using the Pixel option instead. It gives
> > exactly the precision of the actual pixel data.
> >
> > So if the image is 16-bit float, this will yield
> > (0,014557;0,053680;0,827148) for what is (32;66;235) in RGB. That
> > should be precise enough :)
> >
>
> Hi.  This sounds promising. Can you please explain what you mean by "the
> pixel option" ?  How can I enter values like this?  I would actually prefer
> 16-bit integer, but float could work too.

Wait, are we talking about color picker which is a tool for picking
colors from images or a color selector dialog when you tell GIMP what
color to use for foreground and/or background?

If it's color picker, you can choose the Pixel option in the drop-down
list that's in the top right corner of the canvas. In that case,
channel values will be displayed in whatever pixel format your image
is in: 8-bit int, 16-bit int/float, or 32-bit int/float.

If it's color selection dialog (e.g. what you get when you
double-click on the foreground color in the toolbox), then your only
option to get better precision right now is to switch from 0.255 to
0..100 at the top of the dialog. That will yield a 0..100 range with
one decimal. Not nearly as precise as a full 16-bit int range, I know.

Alex
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Re: High precision color picker

Elliott Balsley
On Fri, Jan 10, 2020 at 8:13 AM Alexandre Prokoudine via gimp-user-list <
[hidden email]> wrote:

> If it's color selection dialog (e.g. what you get when you
> double-click on the foreground color in the toolbox), then your only
> option to get better precision right now is to switch from 0.255 to
> 0..100 at the top of the dialog. That will yield a 0..100 range with
> one decimal. Not nearly as precise as a full 16-bit int range, I know.
>

I'm talking about selecting colors in the toolbox.  So I have my answer
now, thank you.  I'll have to check out the Python scripting.
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