loads and saves image data from and to a byte array

Save Load raw bytes (Img)

	private static byte[] saveImgToBytes(Img img) {
		int w = img.getWidth();
		int h = img.getHeight();
		int n = img.numValues();
		int length = n*4 + 4+4;
		byte[] b = new byte[length];
		// save width
		int i = 0;
		b[i++] = signedByteToByte(w);
		b[i++] = signedByteToByte(w>>8);
		b[i++] = signedByteToByte(w>>16);
		b[i++] = signedByteToByte(w>>24);
		// save height
		b[i++] = signedByteToByte(h);
		b[i++] = signedByteToByte(h>>8);
		b[i++] = signedByteToByte(h>>16);
		b[i++] = signedByteToByte(h>>24);
		// save pixel data
		for(int color: img.getData()){
			b[i]     = signedByteToByte(Pixel.r(color));
			b[i+n]   = signedByteToByte(Pixel.g(color));
			b[i+n*2] = signedByteToByte(Pixel.b(color));
			b[i+n*3] = signedByteToByte(Pixel.a(color));
			i++;
		}
		return b;
	}
	
	private static Img loadImgFromBytes(byte[] data) {
		int w=0, h=0;
		int i = 0;
		// read width
		w |= byteToSignedByte(data[i++]);
		w |= byteToSignedByte(data[i++])<<8;
		w |= byteToSignedByte(data[i++])<<16;
		w |= byteToSignedByte(data[i++])<<24;
		// read height
		h |= byteToSignedByte(data[i++]);
		h |= byteToSignedByte(data[i++])<<8;
		h |= byteToSignedByte(data[i++])<<16;
		h |= byteToSignedByte(data[i++])<<24;
		// read pixel data
		int n = w*h;
		int[] pixels = new int[n];
		for(int j = 0; j < pixels.length; j++,i++){
			int r = byteToSignedByte(data[i]);
			int g = byteToSignedByte(data[i+n]);
			int b = byteToSignedByte(data[i+n*2]);
			int a = byteToSignedByte(data[i+n*3]);
			pixels[j] = Pixel.argb(a, r, g, b);
		}
		
		return new Img(w,h,pixels);
	}