Как сделать скриншот с глубиной цвета 8 бит?

Вот пример для получения 24 и 16 битного скриншота, помогите пожалуйста доработать этот код для создания 8 битного скриншота.

    package javaapplication28;

import java.awt.image.BufferedImage;
import java.awt.image.DataBuffer;
import java.awt.image.DirectColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;

import com.sun.jna.Memory;
import com.sun.jna.platform.win32.GDI32;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinDef.HBITMAP;
import com.sun.jna.platform.win32.WinDef.HDC;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinGDI;
import com.sun.jna.platform.win32.WinGDI.BITMAPINFO;
import java.awt.image.DataBufferByte;
import java.awt.image.DataBufferInt;
import java.awt.image.DataBufferUShort;

public class SupportGDI {

    // 24bit
    public static final DirectColorModel SCREENSHOT_COLOR_MODEL_24 = new DirectColorModel(24, 0x00FF0000, 0xFF00, 0xFF);
    // 16bit
    public static final DirectColorModel SCREENSHOT_COLOR_MODEL_16 = new DirectColorModel(16, 0x7C00, 0x3E0, 0x1F);
    // 8bit
    public static final DirectColorModel SCREENSHOT_COLOR_MODEL_8 = new DirectColorModel(8, 3, 3, 2);

    public static final int[] SCREENSHOT_BAND_MASKS_24 = {
        SCREENSHOT_COLOR_MODEL_24.getRedMask(),
        SCREENSHOT_COLOR_MODEL_24.getGreenMask(),
        SCREENSHOT_COLOR_MODEL_24.getBlueMask()
    };
    public static final int[] SCREENSHOT_BAND_MASKS_16 = {
        SCREENSHOT_COLOR_MODEL_16.getRedMask(),
        SCREENSHOT_COLOR_MODEL_16.getGreenMask(),
        SCREENSHOT_COLOR_MODEL_16.getBlueMask()
    };
    public static final int[] SCREENSHOT_BAND_MASKS_8 = {
        SCREENSHOT_COLOR_MODEL_8.getRedMask(),
        SCREENSHOT_COLOR_MODEL_8.getGreenMask(),
        SCREENSHOT_COLOR_MODEL_8.getBlueMask()
    };

    public static BufferedImage getScreenshot(HWND target, int width, int height) throws Exception {
        int bit = 8;
        HDC hdcTarget = User32.INSTANCE.GetDC(target);
        HDC hdcTargetMem = GDI32.INSTANCE.CreateCompatibleDC(hdcTarget);
        HBITMAP hBitmap = GDI32.INSTANCE.CreateCompatibleBitmap(hdcTarget, width, height);
        GDI32.INSTANCE.SelectObject(hdcTargetMem, hBitmap);
        GDI32.INSTANCE.BitBlt(hdcTargetMem, 0, 0, width, height, hdcTarget, 0, 0, GDI32.SRCCOPY);
        //
        int bufferSize = width * height;
        int pixelByte;
        DirectColorModel colorModel;
        int[] bandMask;
        short bitCount;
        //
        switch (bit) {
            case 24:
                pixelByte = 4;
                colorModel = SCREENSHOT_COLOR_MODEL_24;
                bandMask = SCREENSHOT_BAND_MASKS_24;
                bitCount = 32;
                break;
            case 16:
                pixelByte = 2;
                colorModel = SCREENSHOT_COLOR_MODEL_16;
                bandMask = SCREENSHOT_BAND_MASKS_16;
                bitCount = 16;
                break;
            case 8:
                pixelByte = 1;
                colorModel = SCREENSHOT_COLOR_MODEL_8;
                bandMask = SCREENSHOT_BAND_MASKS_8;
                bitCount = 8;
                break;
            default:
                throw new Exception("unknown bit");
        }
        //
        BITMAPINFO bmi = new BITMAPINFO();
        bmi.bmiHeader.biWidth = width;
        bmi.bmiHeader.biHeight = -height;
        bmi.bmiHeader.biPlanes = 1;
        bmi.bmiHeader.biBitCount = bitCount;
        bmi.bmiHeader.biCompression = WinGDI.BI_RGB;
        //

        Memory buffer = new Memory(bufferSize * pixelByte);
        GDI32.INSTANCE.GetDIBits(hdcTarget, hBitmap, 0, height, buffer, bmi, WinGDI.DIB_RGB_COLORS);
        DataBuffer dataBuffer;
        switch (bit) {
            case 24:
                dataBuffer = new DataBufferInt(buffer.getIntArray(0, bufferSize), bufferSize);
                break;
            case 16:
                dataBuffer = new DataBufferUShort(buffer.getShortArray(0, bufferSize), bufferSize);
                break;
            case 8:
                dataBuffer = new DataBufferByte(buffer.getByteArray(0, bufferSize), bufferSize);
                break;
            default:
                throw new Exception("unknown bit");
        }

        WritableRaster raster = Raster.createPackedRaster(dataBuffer, width, height, width, bandMask, null);
        GDI32.INSTANCE.DeleteObject(hBitmap);
        GDI32.INSTANCE.DeleteDC(hdcTargetMem);
        User32.INSTANCE.ReleaseDC(target, hdcTarget);
        return new BufferedImage(colorModel, raster, false, null);
    }

}