// For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-Java
// The path to the documents directory.
String dataDir = Utils.getSharedDataDir(GenerateThumbnailofWorksheet.class) + "TechnicalArticles/";
// Instantiate and open an Excel file
Workbook book = new Workbook(dataDir + "book1.xlsx");

// Define ImageOrPrintOptions
ImageOrPrintOptions imgOptions = new ImageOrPrintOptions();
// Set the vertical and horizontal resolution
imgOptions.setVerticalResolution(200);
imgOptions.setHorizontalResolution(200);
// Set the image's format
imgOptions.setImageType(ImageType.JPEG);
// One page per sheet is enabled
imgOptions.setOnePagePerSheet(true);

// Get the first worksheet
Worksheet sheet = book.getWorksheets().get(0);
// Render the sheet with respect to specified image/print options
SheetRender sr = new SheetRender(sheet, imgOptions);
// Render the image for the sheet
sr.toImage(0, dataDir + "mythumb.jpg");

// Creating Thumbnail
java.awt.Image img = ImageIO.read(new File(dataDir + "mythumb.jpg")).getScaledInstance(100, 100, BufferedImage.SCALE_SMOOTH);
BufferedImage img1 = new BufferedImage(100, 100, BufferedImage.TYPE_INT_RGB);
img1.createGraphics().drawImage(
		ImageIO.read(new File(dataDir + "mythumb.jpg")).getScaledInstance(100, 100, img.SCALE_SMOOTH), 0, 0, null);
ImageIO.write(img1, "jpg", new File(dataDir + "GTOfWorksheet_out.jpg"));