Re: [ferret_users] data-adapted centered palette with white always at zero

[William Kessler <william.s.kessler@xxxxxxxx>]

One idea to center the zero is to use levels (-inf)(your-other-levels)(inf)

A really simple blue-lightgray-red that works well for centered anomalies is

 0   20   20  100
45   95   95   95
55   95   95   95
100 100   20   20

(of course you can change the 95s to 100s to make the center white, but I find the light gray deemphasizes the near-zero values which I think is the goal here)

This is simple enough that you could have your script write it out as a dummy palette file every time, shifting the gray center to the zero of your data as determined before every SHADE/FILL.

BK

> On Apr 2, 2020, at 12:43 AM, Olivier Marti <olivier.marti@xxxxxxxxxxxx> wrote:
> 
> I don't th!ink ferret distributes palets with a white band in the middle. You will have to create it yourself.
> 
> Here is an exemple : 
>    0.0   80.0    0.0  100.0
>    10.0   30.0   20.0  100.0
>    45.0    0.0  100.0    0.0
>    45.1  100.0  100.0  100.0
>    54.9  100.0  100.0  100.0
>    55.0  100.0  100.0    0.0
>    60.0  100.0   80.0    0.0
>    78.0  100.0    0.0    0.0
>    82.0   80.0    0.0    0.0
>    92.0   60.0   50.0   50.0
>   100.0  100.0   75.0   75.0
> 
> 
> You may also want to suppress the 0 level, which something like
> 
> SHADE/LEV=(-10,10,1)DEL(0)
> 
> I don't know how you can use DEL(0) with LEV=10H
> 
> Olivier
> 
>> Le 2 avr. 2020 à 05:49, Ryo Furue <furue@xxxxxxxxxx> a écrit :
>> 
>> Hi Fabio,
>> 
>> 
>> On Thu, Apr 2, 2020 at 12:14 AM Fabio B. <xxtraloud@xxxxxxxx> wrote:
>> 
>> Useful options to do what I want. Is there any way to set 0 to a 
>> particular color, or to have 0 to be white? Still the lev=10C puts the 0 
>> at the center but I don't understand how 0 values are colored because I 
>> see either val>0 or val<0 on the legend.
>> 
>> That's a nice question.  I have some ideas, but other people may have better ones.  In addition, the email messages are archived and searchable and therefore are a great resource for future users.  So, why don't you post the question to the Ferret mailing list? 
>> 
>> Cheers,
>> Ryo
>> 
> 
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