Compresses SrcImage using selected DXTn compression into DestImage.

procedure DXTCompressImage(const SrcImage: TImageData; 
                           var DestImage: TImageData; 
                           DXTFormat: TImageFormat; 
                           Compressor: TDXTCompressor = dcClusterFit; 
                           Metric: TColorMetric = cmPerceptual);

ImagingSquishLib (at line 55)

DestImage should be cleared before calling.