private static BufferedImage createJPEG4 ( Raster raster ) { int w = raster . getWidth ( ) ; int h = raster . getHeight ( ) ; byte [ ] rgb = new byte [ w * h * 3 ] ; float [ ] Y = raster . getSamples ( 0 , 0 , w , h , 0 , ( float [ ] ) null ) ; float [ ] Cb = raster . getSamples ( 0 , 0 , w , h , 1 , ( float [ ] ) null ) ; float [ ] Cr = raster . getSamples ( 0 , 0 , w , h , 2 , ( float [ ] ) null ) ; float [ ] K = raster . getSamples ( 0 , 0 , w , h , 3 , ( float [ ] ) null ) ; for ( int i = 0 , imax = Y . length , base = 0 ; i < imax ; i ++ , base += 3 ) { float k = 220 - K [ i ] , y = 255 - Y [ i ] , cb = 255 - Cb [ i ] , cr = 255 - Cr [ i ] ; double val = y + 1.402 * ( cr - 128 ) - k ; val = ( val - 128 ) * .65f + 128 ; rgb [ base ] = val < 0.0 ? ( byte ) 0 : val > 255.0 ? ( byte ) 0xff : ( byte ) ( val + 0.5 ) ; val = y - 0.34414 * ( cb - 128 ) - 0.71414 * ( cr - 128 ) - k ; val = ( val - 128 ) * .65f + 128 ; rgb [ base + 1 ] = val < 0.0 ? ( byte ) 0 : val > 255.0 ? ( byte ) 0xff : ( byte ) ( val + 0.5 ) ; val = y + 1.772 * ( cb - 128 ) - k ; val = ( val - 128 ) * .65f + 128 ; rgb [ base + 2 ] = val < 0.0 ? ( byte ) 0 : val > 255.0 ? ( byte ) 0xff : ( byte ) ( val + 0.5 ) ; } raster = Raster . createInterleavedRaster ( new DataBufferByte ( rgb , rgb . length ) , w , h , w * 3 , 3 , new int [ ] { 0 , 1 , 2 } , null ) ; ColorSpace cs = ColorSpace . getInstance ( ColorSpace . CS_sRGB ) ; ColorModel cm = new ComponentColorModel ( cs , false , true , Transparency . OPAQUE , DataBuffer . TYPE_BYTE ) ; return new BufferedImage ( cm , ( WritableRaster ) raster , true , null ) ; }
Java s ImageIO can t process 4 - component images and Java2D can t apply AffineTransformOp either so convert raster data to RGB . Technique due to MArk Stephens . Free for any use .