[postgis-users] raster output

[Nordgren, Bryce -FS]

Ahhh, you'll be looking for a while. :)  PostGIS raster does not currently interpret raster band data as color information. If it started out as RGB, you can input all three bands and manipulate them however you see fit. However, you can't output a color jpeg/png if you're starting with a single band of data. Additionally, if you import a single band image with associated pallete, you'll lose the color information. On the upside, if you have a full color image, you can read it in manipulate it, and spit it back out.

Try exporting the single band of interest, then adding a pallete using the external program of your choice. That will also let you "stretch" the image to your heart's content. I'm 90% sure you can do all your desired postprocessing with ImageMagick. :)

Bryce

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Stephen Crawford
Sent: Wednesday, December 21, 2011 3:51 PM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] raster output

Thanks for getting back to me.  I want to do something like #3, but I just don't understand the work flow.  I have raw data as a one band raster in postGIS, and the (seemingly) simple thing i would like to do is output the entire table as a  jpg or png with the cells classified by color.  I see references to "color tables" and "palettes".  I can't seem to figure out where I can define "if cell val < 0.5, color = 0, 0, 255" etc.