Ogre::ColourValue Ogre::Image::getColourAt method

Noting with this function that Ogre::ColourValue  return Ogre::ColourValue type with RGBA or what ever your image encoding method provides as normalized in value ranges between [0,1].

This means that if you want to properly configure the channels you need to use the channel bit multiplier accordingly, thus, 

for the RGBA channel at 8 bits per channel with 256.0f different color ranges you'd have the following call in restoring the channels R value...assuming an Ogre::Image* image 

OgreColourValue coln =  img->getColourAt(x,y,z);

Ogre::ColourValue col = Ogre::ColourValue(256.0f*col.r, 256.0f*col.g, 256.0f*col.b, 256.0f*col.a);

where col provides the proper (non normalized color value according to your image type bit set.

A 16 bit channel would have a 256^2 channel multiplier

24 bit channel a 256^3 channel multiplier 

and so forth.

The alternate method suggests something like

Ogre::PixelBox pixel_box = img->getPixelBox();

where you could use a getData call, but this requires you to do a little more pointer array work on the uchar* data set where you'd likely reverse the equation process found in a past posting of mine (namely inverting the getPixel process for the ImageBuffer class from ImageStuff.cpp)


Here's a picture on a running project.  Basically loading my 32 bit RGBA heightmap.