[Gdal-dev] RE: Urgent help needed with image conversion for the JimGray search

[Norman Vine]

Forde, Sean writes:
> 
> Friends - can I use gdal_translate to convert 11bit geotiff 
> to jpeg? Can you tell me the command line arguments?

gdal_translate -scale 0 2047 -of JPEG $INFILE.tif  $OUTFILE.jpgshould work

Note I like to use a non-linear scale as demonstrated in the following
Python code

####################
from PIL import Image
import numarray as NA

def ImageToArray(im,power=8):
    """ """
    cols = im.size[0]
    rows = im.size[1]
    r = NA.fromstring(im.tostring(),NA.UInt16)
    #r = NA.clip(r,0,(2**power)-1)
    r.shape = rows,cols
    return r*(1.0/(2**power))

def ArrayToImage(arr,extents,max_pix=255.0,scale=1.0):
    """ """
    h = extents[0]
    w = extents[1]
    band = arr*(max_pix/scale)
    return Image.fromstring('L',(w,h),(band.astype('b')).tostring())

img = Image.open("roi.1875402401.tif")
a = ImageToArray(img,11)
a = NA.exp(a)
a -= a.min()
a *= (1.0/a.max())
img = ArrayToImage(a,a.shape)
img.save("roi.1875402401.png","PNG")
#############################


Let me know if you need a hand translating these

Norman


> 
> ________________________________
> 
> From: owner-software at amazon.com 
> [mailto:owner-software at amazon.com] On Behalf Of Vogels, Werner
> Sent: Friday, February 02, 2007 8:50 AM
> To: software at amazon.com
> Cc: turk-jim-gray at amazon.com
> Subject: Urgent help needed with image conversion for the Jim 
> Gray search
> 
> 
> As you guys may know computer science icon Jim Gray 
> disappeared at sea last Sunday, and the Coast Guard has not 
> been able to find any trace. It is a complete mystery.
>  
> We have started an effort to find him by getting access to 
> satellite data with the intention to load it into Mechanical 
> Turk, the turk team has worked deep into the night to make 
> this happen. 
>  
> We have however hit an obstacle to which we have no answer: 
> the image format is 16 bit panchromatic with on 11 bits used 
> for data (tiff). If you view this in a regular viewer it will 
> be pitch black. We'll need to run a conversion similar to 
> what is described here:
>  
> http://www.eurimage.com/products/qb_photoshop/photoshop.html 
> <http://www.eurimage.com/products/qb_photoshop/photoshop.html> 
>  
> to get the images into a spectrum that is usable.
>  
> Does any of you know of any automated tools or procedures 
> that can make this happen?
>  
> Some of the images can be found at: internal/~deflaux/JimGray
>  
> --
> Werner
> <http://openphi.net/tenacious/> 
>