[GRASS-user] Can GRASS create color table in16 bit?

GRASS GRASS user
1

Dear all,

I try to create color table in 16 bit. That is in attachment. But, when I set color table interactively, then I input that file (in attachment), then I click Load. There is a message : “Invalid color table format”. Do I missing something?

Thank you.

Regards,
mega

(attachments)

spl1.file (4.74 KB)

2

On 1/2/21 9:13 AM, mega saputra wrote:

Dear all,

I try to create color table in 16 bit. That is in attachment. But, when I set color table interactively, then I input that file (in attachment), then I click Load. There is a message : "Invalid color table format". Do I missing something?

I think you have the categories and colors backwards. RGB color tables are (throughout all GIS and image software) always three 8 bit numbers, with optionally a fourth alpha band, also 8 bit. In your rules file you attach raster values (16 bit numbers in your case) to certain RGB values. So, To define a color table for your raster you put the raster values in the left column and R:G:B (0-255) combinations in the right column.

Here's an example of the srtm (elevation) builtin color table. Maybe you can use it as a template.

-11000 0:0:0
-500 0:0:10
-300 0:0:20
-200 0:0:70
-100 0:0:130
-50 0:0:205
0 100:128:255
0.1 57:151:105
100 117:194:93
200 230:230:128
500 202:158:75
1000 214:187:98
2000 185:154:100
3000 220:220:220
5000 250:250:250
8850 255:255:255
nv 255:255:255
default 255:255:255

It spans the range of elevations from sea bottom (-11000 m) to the peak of the Himalaya Mts. (8850 m)

HTH

Thank you.

Regards,
mega

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3

AFAIK, GRASS only supports 8 bit color definitions, i.e. 0-255 for each of R, G, and B. This allows for 16 million different color tones which is generally enough.

Moritz

Am 2. Januar 2021 08:13:07 MEZ schrieb mega saputra megasaputra8@gmail.com:

Dear all,

I try to create color table in 16 bit. That is in attachment. But, when I set color table interactively, then I input that file (in attachment), then I click Load. There is a message : “Invalid color table format”. Do I missing something?

Thank you.

Regards,
mega

4

Ok, thanks.

On Sun, Jan 3, 2021 at 12:18 AM Moritz Lennert <mlennert@club.worldonline.be> wrote:

AFAIK, GRASS only supports 8 bit color definitions, i.e. 0-255 for each of R, G, and B. This allows for 16 million different color tones which is generally enough.

Moritz

Am 2. Januar 2021 08:13:07 MEZ schrieb mega saputra <megasaputra8@gmail.com>:

Dear all,

I try to create color table in 16 bit. That is in attachment. But, when I set color table interactively, then I input that file (in attachment), then I click Load. There is a message : “Invalid color table format”. Do I missing something?

Thank you.

Regards,
mega

5

Well, perhaps this is not what the question was about, but while the color table itself probably is 0-255 in colours definition, you can apply color tables to 16bit raster data. I use color tables and also rgb color channels on Sentinel and Landsat-8 data saved as 16-bit.
Regards,
Tomáš Brunclík

______________________________________________________________

Od: "mega saputra" <megasaputra8@gmail.com>
Komu: "Moritz Lennert" <mlennert@club.worldonline.be>, "Micha Silver" <tsvibar@gmail.com>
Datum: 03.01.2021 13:54
Předmět: Re: [GRASS-user] Can GRASS create color table in16 bit?

CC: <grass-user@lists.osgeo.org>

Ok, thanks. On Sun, Jan 3, 2021 at 12:18 AM Moritz Lennert <mlennert@club.worldonline.be> wrote:AFAIK, GRASS only supports 8 bit color definitions, i.e. 0-255 for each of R, G, and B. This allows for 16 million different color tones which is generally enough.MoritzAm 2. Januar 2021 08:13:07 MEZ schrieb mega saputra <megasaputra8@gmail.com>:
Dear all,I try to create color table in 16 bit. That is in attachment. But, when I set color table interactively, then I input that file (in attachment), then I click Load. There is a message : "Invalid color table format". Do I missing something?Thank you.Regards,mega

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