[gdal-dev] Interleave Bands with RasterIO?

[Adam Nowacki]

int bands[4] = { 3, 2, 1, 4 };
GDALDataset::RasterIO(..., 4, bands, 32, 32 * xSize, 1);

but then you probably mixed bits with bytes so:

int bands[4] = { 3, 2, 1, 4 };
GDALDataset::RasterIO(..., 4, bands, 4, 4 * xSize, 1);

craig.miller at spatialminds.com wrote:
> I have a BGRA buffer in memory, and a multi-band RGBA TIF image.  Is it 
> possible to use RasterIO to read in values from each band and neatly 
> interleave them in my buffer.
> 
> For example if I was loading an RGBA image I am hoping to be able to 
> make 4 separate RasterIO calls. 
> 
> Assuming a BGRA image looks like:
> 
> 0 - blue byte
> 8 - green byte
> 16 - red byte
> 24 - alpha byte
> 32 - blue byte
> 40 - green byte
> 48 - red byte
> 56 - alpha byte
> 64 - ....
> 
> The first RasterIO call would read in the blue values and insert them at 
> 0, 32, 64, etc making it look like:
> 
> 0 - blue byte
> 8 -
> 16 -
> 24 -
> 32 - blue byte
> 40 -
> 48 -
> 56 -
> 64 - ....
> 
> The second RasterIO call would read the green values and insert them at 
> 8, 40, etc making it look like:
> 
> 0 - blue byte
> 8 - green byte
> 16 -
> 24 -
> 32 - blue byte
> 40 - green byte
> 48 -
> 56 -
> 64 - ....
> 
> Rinse and repeat for red and alpha.
> 
> Is this possible, or is there a much much simpler way that I'm 
> overlooking?  I've been looking at the paramaters for RasterIO but can't 
> seem to get it to work.  I do understand that I can just read the values 
> into a separate buffer and memcpy them over to my image buffer.  I was 
> trying to minimize the total number of times the same data has to be copied.
> 
> Thanks for the help.
> 
> Craig
> 
>  
> 
> 
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