package stirling.software.SPDF.controller.api.misc; import java.awt.Color; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.geom.AffineTransform; import java.awt.image.BufferedImage; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.util.Random; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDPage; import org.apache.pdfbox.pdmodel.PDPageContentStream; import org.apache.pdfbox.pdmodel.common.PDRectangle; import org.apache.pdfbox.pdmodel.graphics.image.LosslessFactory; import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject; import org.apache.pdfbox.rendering.PDFRenderer; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.multipart.MultipartFile; import io.github.pixee.security.Filenames; import io.swagger.v3.oas.annotations.Operation; import io.swagger.v3.oas.annotations.tags.Tag; import jakarta.validation.Valid; import lombok.RequiredArgsConstructor; import lombok.extern.slf4j.Slf4j; import stirling.software.SPDF.model.api.misc.FakeScanRequest; import stirling.software.common.service.CustomPDFDocumentFactory; import stirling.software.common.util.WebResponseUtils; @RestController @RequestMapping("/api/v1/misc") @Tag(name = "Misc", description = "Miscellaneous PDF APIs") @RequiredArgsConstructor @Slf4j public class FakeScanController { private final CustomPDFDocumentFactory pdfDocumentFactory; private static final Random RANDOM = new Random(); @PostMapping(value = "/fake-scan", consumes = "multipart/form-data") @Operation( summary = "Convert PDF to look like a scanned document", description = "Applies various effects to make a PDF look like it was scanned, including rotation, noise, and edge softening. Input:PDF Output:PDF Type:SISO") public ResponseEntity fakeScan(@Valid @ModelAttribute FakeScanRequest request) throws IOException { MultipartFile file = request.getFileInput(); // Apply preset first if needed if (!request.isAdvancedEnabled()) { switch (request.getQuality()) { case high -> request.applyHighQualityPreset(); case medium -> request.applyMediumQualityPreset(); case low -> request.applyLowQualityPreset(); } } // Extract values after preset application int baseRotation = request.getRotationValue() + request.getRotate(); int rotateVariance = request.getRotateVariance(); int borderPx = request.getBorder(); float brightness = request.getBrightness(); float contrast = request.getContrast(); float blur = request.getBlur(); float noise = request.getNoise(); boolean yellowish = request.isYellowish(); int resolution = request.getResolution(); FakeScanRequest.Colorspace colorspace = request.getColorspace(); try (PDDocument document = pdfDocumentFactory.load(file)) { PDDocument outputDocument = new PDDocument(); PDFRenderer pdfRenderer = new PDFRenderer(document); for (int i = 0; i < document.getNumberOfPages(); i++) { // Render page to image with specified resolution BufferedImage image = pdfRenderer.renderImageWithDPI(i, resolution); // 1. Convert to grayscale or keep color BufferedImage processed; if (colorspace == FakeScanRequest.Colorspace.grayscale) { processed = new BufferedImage( image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB); Graphics2D gGray = processed.createGraphics(); gGray.setColor(Color.BLACK); gGray.fillRect(0, 0, image.getWidth(), image.getHeight()); gGray.drawImage(image, 0, 0, null); gGray.dispose(); // Convert to grayscale manually for (int y = 0; y < processed.getHeight(); y++) { for (int x = 0; x < processed.getWidth(); x++) { int rgb = processed.getRGB(x, y); int r = (rgb >> 16) & 0xFF; int g = (rgb >> 8) & 0xFF; int b = rgb & 0xFF; int gray = (r + g + b) / 3; int grayRGB = (gray << 16) | (gray << 8) | gray; processed.setRGB(x, y, grayRGB); } } } else { processed = new BufferedImage( image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB); Graphics2D gCol = processed.createGraphics(); gCol.drawImage(image, 0, 0, null); gCol.dispose(); } // 2. Add border with randomized grey gradient int baseW = processed.getWidth() + 2 * borderPx; int baseH = processed.getHeight() + 2 * borderPx; boolean vertical = RANDOM.nextBoolean(); float startGrey = 0.6f + 0.3f * RANDOM.nextFloat(); float endGrey = 0.6f + 0.3f * RANDOM.nextFloat(); Color startColor = new Color( Math.round(startGrey * 255), Math.round(startGrey * 255), Math.round(startGrey * 255)); Color endColor = new Color( Math.round(endGrey * 255), Math.round(endGrey * 255), Math.round(endGrey * 255)); BufferedImage composed = new BufferedImage(baseW, baseH, processed.getType()); Graphics2D gBg = composed.createGraphics(); for (int y = 0; y < baseH; y++) { for (int x = 0; x < baseW; x++) { float frac = vertical ? (float) y / (baseH - 1) : (float) x / (baseW - 1); int r = Math.round( startColor.getRed() + (endColor.getRed() - startColor.getRed()) * frac); int g = Math.round( startColor.getGreen() + (endColor.getGreen() - startColor.getGreen()) * frac); int b = Math.round( startColor.getBlue() + (endColor.getBlue() - startColor.getBlue()) * frac); composed.setRGB(x, y, new Color(r, g, b).getRGB()); } } gBg.drawImage(processed, borderPx, borderPx, null); gBg.dispose(); // 3. Rotate the entire composed image double pageRotation = baseRotation; if (baseRotation != 0 || rotateVariance != 0) { pageRotation += (RANDOM.nextDouble() * 2 - 1) * rotateVariance; } BufferedImage rotated; int w = composed.getWidth(); int h = composed.getHeight(); int rotW = w; int rotH = h; // Skip rotation entirely if no rotation is needed if (pageRotation == 0) { rotated = composed; } else { double radians = Math.toRadians(pageRotation); double sin = Math.abs(Math.sin(radians)); double cos = Math.abs(Math.cos(radians)); rotW = (int) Math.floor(w * cos + h * sin); rotH = (int) Math.floor(h * cos + w * sin); BufferedImage rotatedBg = new BufferedImage(rotW, rotH, composed.getType()); Graphics2D gBgRot = rotatedBg.createGraphics(); for (int y = 0; y < rotH; y++) { for (int x = 0; x < rotW; x++) { float frac = vertical ? (float) y / (rotH - 1) : (float) x / (rotW - 1); int r = Math.round( startColor.getRed() + (endColor.getRed() - startColor.getRed()) * frac); int g = Math.round( startColor.getGreen() + (endColor.getGreen() - startColor.getGreen()) * frac); int b = Math.round( startColor.getBlue() + (endColor.getBlue() - startColor.getBlue()) * frac); rotatedBg.setRGB(x, y, new Color(r, g, b).getRGB()); } } gBgRot.dispose(); rotated = new BufferedImage(rotW, rotH, composed.getType()); Graphics2D g2d = rotated.createGraphics(); g2d.drawImage(rotatedBg, 0, 0, null); AffineTransform at = new AffineTransform(); at.translate((rotW - w) / 2.0, (rotH - h) / 2.0); at.rotate(radians, w / 2.0, h / 2.0); g2d.setRenderingHint( RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC); g2d.setRenderingHint( RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY); g2d.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.drawImage(composed, at, null); g2d.dispose(); } // 4. Scale and center the rotated image to cover the original page size PDRectangle origPageSize = document.getPage(i).getMediaBox(); float origW = origPageSize.getWidth(); float origH = origPageSize.getHeight(); float scale = Math.max(origW / rotW, origH / rotH); float drawW = rotW * scale; float drawH = rotH * scale; float offsetX = (origW - drawW) / 2f; float offsetY = (origH - drawH) / 2f; // 5. Apply adaptive blur and edge softening BufferedImage softened = softenEdges( rotated, Math.max(10, Math.round(Math.min(rotW, rotH) * 0.02f)), startColor, endColor, vertical); BufferedImage blurred = applyGaussianBlur(softened, blur); // 6. Adjust brightness and contrast BufferedImage adjusted = adjustBrightnessContrast(blurred, brightness, contrast); // 7. Add noise and yellowish effect to the content if (yellowish) { applyYellowishEffect(adjusted); } addGaussianNoise(adjusted, noise); // 8. Write to PDF PDPage newPage = new PDPage(new PDRectangle(origW, origH)); outputDocument.addPage(newPage); try (PDPageContentStream contentStream = new PDPageContentStream(outputDocument, newPage)) { PDImageXObject pdImage = LosslessFactory.createFromImage(outputDocument, adjusted); contentStream.drawImage(pdImage, offsetX, offsetY, drawW, drawH); } } // Save to byte array ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); outputDocument.save(outputStream); outputDocument.close(); String outputFilename = Filenames.toSimpleFileName(file.getOriginalFilename()) .replaceFirst("[.][^.]+$", "") + "_scanned.pdf"; return WebResponseUtils.bytesToWebResponse( outputStream.toByteArray(), outputFilename, MediaType.APPLICATION_PDF); } } private BufferedImage softenEdges( BufferedImage image, int featherRadius, Color startColor, Color endColor, boolean vertical) { int width = image.getWidth(); int height = image.getHeight(); BufferedImage output = new BufferedImage(width, height, image.getType()); for (int y = 0; y < height; y++) { for (int x = 0; x < width; x++) { int dx = Math.min(x, width - 1 - x); int dy = Math.min(y, height - 1 - y); int d = Math.min(dx, dy); float frac = vertical ? (float) y / (height - 1) : (float) x / (width - 1); int rBg = Math.round( startColor.getRed() + (endColor.getRed() - startColor.getRed()) * frac); int gBg = Math.round( startColor.getGreen() + (endColor.getGreen() - startColor.getGreen()) * frac); int bBg = Math.round( startColor.getBlue() + (endColor.getBlue() - startColor.getBlue()) * frac); int bgVal = new Color(rBg, gBg, bBg).getRGB(); int fgVal = image.getRGB(x, y); float alpha = d < featherRadius ? (float) d / featherRadius : 1.0f; int blended = blendColors(fgVal, bgVal, alpha); output.setRGB(x, y, blended); } } return output; } private int blendColors(int fg, int bg, float alpha) { int r = Math.round(((fg >> 16) & 0xFF) * alpha + ((bg >> 16) & 0xFF) * (1 - alpha)); int g = Math.round(((fg >> 8) & 0xFF) * alpha + ((bg >> 8) & 0xFF) * (1 - alpha)); int b = Math.round((fg & 0xFF) * alpha + (bg & 0xFF) * (1 - alpha)); return (r << 16) | (g << 8) | b; } private BufferedImage applyGaussianBlur(BufferedImage image, double sigma) { if (sigma <= 0) { return image; } // Scale sigma based on image size to maintain consistent blur effect double scaledSigma = sigma * Math.min(image.getWidth(), image.getHeight()) / 1000.0; int radius = Math.max(1, (int) Math.ceil(scaledSigma * 3)); int size = 2 * radius + 1; float[] data = new float[size * size]; double sum = 0.0; // Generate Gaussian kernel for (int i = -radius; i <= radius; i++) { for (int j = -radius; j <= radius; j++) { double xDistance = (double) i * i; double yDistance = (double) j * j; double g = Math.exp(-(xDistance + yDistance) / (2 * scaledSigma * scaledSigma)); data[(i + radius) * size + j + radius] = (float) g; sum += g; } } // Normalize kernel for (int i = 0; i < data.length; i++) { data[i] /= (float) sum; } // Create and apply convolution java.awt.image.Kernel kernel = new java.awt.image.Kernel(size, size, data); java.awt.image.ConvolveOp op = new java.awt.image.ConvolveOp(kernel, java.awt.image.ConvolveOp.EDGE_NO_OP, null); // Apply blur with high-quality rendering hints BufferedImage result = new BufferedImage(image.getWidth(), image.getHeight(), image.getType()); Graphics2D g2d = result.createGraphics(); g2d.setRenderingHint( RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC); g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY); g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.drawImage(op.filter(image, null), 0, 0, null); g2d.dispose(); return result; } private void applyYellowishEffect(BufferedImage image) { for (int x = 0; x < image.getWidth(); x++) { for (int y = 0; y < image.getHeight(); y++) { int rgb = image.getRGB(x, y); int r = (rgb >> 16) & 0xFF; int g = (rgb >> 8) & 0xFF; int b = rgb & 0xFF; // Stronger yellow tint while preserving brightness float brightness = (r + g + b) / 765.0f; // Normalize to 0-1 r = Math.min(255, (int) (r + (255 - r) * 0.18f * brightness)); g = Math.min(255, (int) (g + (255 - g) * 0.12f * brightness)); b = Math.max(0, (int) (b * (1 - 0.25f * brightness))); image.setRGB(x, y, (r << 16) | (g << 8) | b); } } } private void addGaussianNoise(BufferedImage image, double strength) { if (strength <= 0) return; // Scale noise based on image size double scaledStrength = strength * Math.min(image.getWidth(), image.getHeight()) / 1000.0; for (int x = 0; x < image.getWidth(); x++) { for (int y = 0; y < image.getHeight(); y++) { int rgb = image.getRGB(x, y); int r = (rgb >> 16) & 0xFF; int g = (rgb >> 8) & 0xFF; int b = rgb & 0xFF; // Generate noise with better distribution double noiseR = RANDOM.nextGaussian() * scaledStrength; double noiseG = RANDOM.nextGaussian() * scaledStrength; double noiseB = RANDOM.nextGaussian() * scaledStrength; // Apply noise with better color preservation r = Math.min(255, Math.max(0, r + (int) noiseR)); g = Math.min(255, Math.max(0, g + (int) noiseG)); b = Math.min(255, Math.max(0, b + (int) noiseB)); image.setRGB(x, y, (r << 16) | (g << 8) | b); } } } private BufferedImage adjustBrightnessContrast( BufferedImage image, float brightness, float contrast) { BufferedImage output = new BufferedImage(image.getWidth(), image.getHeight(), image.getType()); for (int y = 0; y < image.getHeight(); y++) { for (int x = 0; x < image.getWidth(); x++) { int rgb = image.getRGB(x, y); int r = (int) (((((rgb >> 16) & 0xFF) - 128) * contrast + 128) * brightness); int g = (int) (((((rgb >> 8) & 0xFF) - 128) * contrast + 128) * brightness); int b = (int) ((((rgb & 0xFF) - 128) * contrast + 128) * brightness); r = Math.min(255, Math.max(0, r)); g = Math.min(255, Math.max(0, g)); b = Math.min(255, Math.max(0, b)); output.setRGB(x, y, (r << 16) | (g << 8) | b); } } return output; } }