[Qgis-user] QGIS Master and Rasters to grayscale

Thu Jun 21 04:02:05 PDT 2012

There is a sample of this data at:

http://www.ordnancesurvey.co.uk/docs/sample-data/10k-raster-colour-sampl
e-data.zip

If you turn this grayscale in 1.9 it just turns grey (rgb 127,127,127)
all over. In 1.8 if you choose grayscale it displays it with the rgb
values displayed below.

So I created a colormap if anyone is interested. I took the values from
what QGIS 1.8 did automatically to turn the data grayscale. 

Value - r ,g ,b
0 = 255,255,255
1 = 0,0,0
2 = 226,226,226
3 = 150,150,150
4 = 218,218,218
5 = 232,232,232
6 = 232,232,232
7 = 230,230,230
8 = 249,249,249
9 = 252,252,252

I have created a qml file if anyone would like it you can download it
from here:

https://docs.google.com/open?id=0B6r5nAOdEBZrRFpjVlBLZm1BSkE

This was quite easy as there were only 10 values defined in the data.

The OS 25000 and 50000 rasters have 255 different colours in them. 

James

  | 
Nicholas Pearson Associates | 
T:  | M: 
http://www.npaconsult.co.uk/ 
-----Original Message-----
From: qgis-user-bounces at lists.osgeo.org
[mailto:qgis-user-bounces at lists.osgeo.org] On Behalf Of James Stott
Sent: 19 June 2012 14:40
To: Etienne Tourigny
Cc: qgis-user at lists.osgeo.org
Subject: Re: [Qgis-user] QGIS Master and Rasters to grayscale

Yes.

It still turns into one colour.

James Stott BSc (Hons) MSc | Senior Professional Nicholas Pearson
Associates | 30 Brock Street | Bath | BA1 2LN
T: 01225 445548 | M: -
http://www.npaconsult.co.uk/
-----Original Message-----
From: Etienne Tourigny [mailto:etourigny.dev at gmail.com]
Sent: 19 June 2012 14:33
To: James Stott
Cc: Salvatore Larosa; qgis-user at lists.osgeo.org
Subject: Re: [Qgis-user] QGIS Master and Rasters to grayscale

DId you click on "Load" Button?

On Tue, Jun 19, 2012 at 10:22 AM, James Stott
<James.Stott at npaconsult.co.uk> wrote:
>> You can still do that by selecting "singleband gray", and choose the
default contrast enhancement in the options.
>
> This just turns the raster into 1 gray colour: 127, 127, 127
>
>> can you share a bit sample of your raster?
>
> Technically I don't think I supposed to share the data as it is
Ordnance Survey data.
>
> I have included the metadata below if this helps:
>
> Driver:
> GDAL provider
> VRT
> Virtual Raster
> Dataset Description
> N:\Projects\10499 BP\Reference\Base Mapping\Raster\10000\OS 10000.vrt 
> Band 1
> STATISTICS_MAXIMUM=9
> STATISTICS_MEAN=3.2746921074487
> STATISTICS_MINIMUM=0
> STATISTICS_STDDEV=3.9133672791329
> Dimensions:
> X: 39370 Y: 31496 Bands: 1
> Origin:
> 385000,95000
> Pixel Size:
> 0.635001,-0.635001
> No Data Value
> -32768
> Data Type:
> GDT_Byte - Eight bit unsigned integer
> Pyramid overviews:
> Layer Spatial Reference System:
> +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000
> ++y_0=-100000 +ellps=airy +towgs84=375,-111,431,0,0,0,0 +units=m 
> ++no_defs
> Layer Extent (layer original source projection):
> 385000.0000000000000000,75000.0000000000000000 : 
> 410000.0000000000000000,95000.0000000000000000
> Band
> Band 1
> Band No
> 1
> No Stats
> No stats collected yet
>
>
> James Stott BSc (Hons) MSc | Senior Professional Nicholas Pearson 
> Associates | 30 Brock Street | Bath | BA1 2LN
> T: 01225 445548 | M: -
> http://www.npaconsult.co.uk/
>
> http://www.npaconsult.co.uk/http://www.npaconsult.co.uk/about-news.asp
>
> From: qgis-user-bounces at lists.osgeo.org 
> [mailto:qgis-user-bounces at lists.osgeo.org] On Behalf Of Salvatore 
> Larosa
> Sent: 19 June 2012 13:02
> To: qgis-user at lists.osgeo.org
> Subject: Re: [Qgis-user] QGIS Master and Rasters to grayscale
>
> Il giorno mar, 19/06/2012 alle 12.42 +0100, James Stott ha scritto:
>> This does make what was a very simple thing to do in 1.8 more time 
>> consuming in 1.9 doesn't it? All I want to do is just turn it 
>> grayscale for display purposes. In 1.8, all I do is select grayscale 
>> from the colormap drop down and push OK and QGIS does it for me. Am I

>> missing something?
>
> Hi James,
> can you share a bit sample of your raster?
>
> Regards,
>
> -SL
>
>
> --
> Salvatore Larosa
> linkedIn: http://linkedin.com/in/larosasalvatore
> twitter: @lrssvt
> skype: s.larosa
> IRC: lrssvt on freenode
>
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