remove blanks

scripts/detect-blank-pages.sh

@@ -0,0 +1,39 @@
+import cv2
+import numpy as np
+import sys
+
+def is_blank_image(image_path, threshold=10, white_value=255, blur_size=5):
+    image = cv2.imread(image_path, cv2.IMREAD_GRAYSCALE)
+    
+    if image is None:
+        print(f"Error: Unable to read the image file: {image_path}")
+        return False
+
+    # Apply Gaussian blur to reduce noise
+    blurred_image = cv2.GaussianBlur(image, (blur_size, blur_size), 0)
+
+    _, thresholded_image = cv2.threshold(blurred_image, white_value - threshold, white_value, cv2.THRESH_BINARY)
+    
+    # Calculate the percentage of white pixels in the thresholded image
+    white_pixels = np.sum(thresholded_image == white_value)
+    total_pixels = thresholded_image.size
+    white_pixel_percentage = (white_pixels / total_pixels) * 100
+
+    return white_pixel_percentage > 99
+
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        print("Usage: python detect_blank_page.py <image_path>")
+        sys.exit(1)
+
+    image_path = sys.argv[1]
+    blank = is_blank_image(image_path)
+
+    if blank:
+        # Return code 1: The image is considered blank.
+        sys.exit(1)
+    else:
+        # Return code 0: The image is not considered blank.
+        sys.exit(0)

src/main/java/stirling/software/SPDF/controller/api/other/BlankPageController.java

@@ -2,6 +2,7 @@ package stirling.software.SPDF.controller.api.other;
 import org.apache.pdfbox.pdmodel.PDDocument;
 import org.apache.pdfbox.pdmodel.PDPage;
 import org.apache.pdfbox.pdmodel.PDPageTree;
+import org.apache.pdfbox.rendering.PDFRenderer;
 import org.apache.pdfbox.text.PDFTextStripper;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
@@ -10,38 +11,30 @@ import org.springframework.web.bind.annotation.RequestPart;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.multipart.MultipartFile;
 import stirling.software.SPDF.utils.ImageFinder;
+import stirling.software.SPDF.utils.ProcessExecutor;
+
+import java.awt.image.BufferedImage;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
+import javax.imageio.ImageIO;
+
 @RestController
 public class BlankPageController {
 
     @PostMapping(consumes = "multipart/form-data", value = "/remove-blanks")
-    public ResponseEntity<byte[]> removeBlankPages(@RequestPart(required = true, value = "fileInput") MultipartFile inputFile, @RequestPart(required = true, value = "processType") int processType) throws IOException, InterruptedException {
-        boolean removeNoText = false;
-        boolean removeNoTextOrImages = false;
-        
-        if(processType == 0) {
-        	removeNoText = true;
-        } else if (processType == 1) {
-        	removeNoTextOrImages = true;
-        } else if (processType == 2) {
-        	//run OCR 
-        	OCRController ocr = new OCRController();
-            ocr.processPdfWithOCR(inputFile, Arrays.asList("eng"), false, false, true, false, "type", "hocr", false);
-            
-        	removeNoText = true;
-        }
-
+    public ResponseEntity<byte[]> removeBlankPages(@RequestPart(required = true, value = "fileInput") MultipartFile inputFile) throws IOException, InterruptedException {
         try {
             PDDocument document = PDDocument.load(inputFile.getInputStream());
             PDPageTree pages = document.getDocumentCatalog().getPages();
             PDFTextStripper textStripper = new PDFTextStripper();
 
-            List<PDPage> pagesToKeep = new ArrayList<>();
+            List<Integer> pagesToKeepIndex = new ArrayList<>();
             int pageIndex = 0;
 
             for (PDPage page : pages) {
@@ -50,28 +43,40 @@ public class BlankPageController {
                 textStripper.setEndPage(pageIndex);
                 String pageText = textStripper.getText(document);
                 boolean hasText = !pageText.trim().isEmpty();
-                boolean hasImages = hasImagesOnPage(page);
-
-                if (removeNoText && removeNoTextOrImages) {
-                    if (hasText || hasImages) {
-                        pagesToKeep.add(page);
-                    }
-                } else if (removeNoText) {
                 if (hasText) {
-                        pagesToKeep.add(page);
+                	pagesToKeepIndex.add(pageIndex);
+                	System.out.print("page " + pageIndex + " has text");
+                	continue;
                 }
-                } else if (removeNoTextOrImages) {
-                    if (hasText && hasImages) {
-                        pagesToKeep.add(page);
-                    }
-                } else {
-                    pagesToKeep.add(page);
+                boolean hasImages = hasImagesOnPage(page);
+                if (hasImages) {
+                	pagesToKeepIndex.add(pageIndex);
+                	System.out.print("page " + pageIndex + " has image");
+                    continue;
                 }
             }
-
+            System.out.print(pagesToKeepIndex.size());
             PDDocument outputDocument = new PDDocument();
-            for (PDPage page : pagesToKeep) {
-                outputDocument.addPage(page);
+            PDFRenderer pdfRenderer = new PDFRenderer(document);
+            for (Integer i : pagesToKeepIndex) {
+                // Create temp file to save the image
+                Path tempFile = Files.createTempFile("image_", ".png");
+
+                // Render image and save as temp file
+                BufferedImage image = pdfRenderer.renderImageWithDPI(i - 1, 300);
+                ImageIO.write(image, "png", tempFile.toFile());
+                
+                List<String> command = new ArrayList<>(Arrays.asList("python3", "/scripts/detect-blank-pages.py", tempFile.toString())); 
+
+                // Run CLI command
+                int returnCode = ProcessExecutor.getInstance(ProcessExecutor.Processes.PYTHON_OPENCV).runCommandWithOutputHandling(command);
+
+				//does contain data
+                if(returnCode ==0) {
+                	outputDocument.addPage(document.getPage(i - 1));
+                } else {
+                	System.out.print("Found blank page skipping, page #" + i);
+                }
             }
 
             ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

src/main/java/stirling/software/SPDF/controller/web/OtherWebController.java

@@ -95,4 +95,11 @@ public class OtherWebController {
         return "other/repair";
     }
     
+    @GetMapping("/remove-blanks")
+    @Hidden
+    public String removeBlanksForm(Model model) {
+        model.addAttribute("currentPage", "remove-blanks");
+        return "other/remove-blanks";
+    }
+    
 }

src/main/resources/templates/home.html

@@ -112,6 +112,8 @@ filter: invert(0.2) sepia(2) saturate(50) hue-rotate(190deg);
                 <div th:replace="~{fragments/card :: card(cardTitle=#{home.flatten.title}, cardText=#{home.flatten.desc}, cardLink='flatten', svgPath='images/flatten.svg')}"></div>
                 
                 <div th:replace="~{fragments/card :: card(cardTitle=#{home.repair.title}, cardText=#{home.repair.desc}, cardLink='repair', svgPath='images/wrench.svg')}"></div>
+                <div th:replace="~{fragments/card :: card(cardTitle=#{home.removeBlanks.title}, cardText=#{home.removeBlanks.desc}, cardLink='remove-blanks', svgPath='images/wrench.svg')}"></div>
+                <div th:replace="~{fragments/card :: card(cardTitle=#{home.compare.title}, cardText=#{home.compare.desc}, cardLink='compare', svgPath='images/wrench.svg')}"></div>
             </div>
         </div>
         <div th:insert="~{fragments/footer.html :: footer}"></div>

src/main/resources/templates/other/remove-blanks.html

@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<html th:lang="${#locale.toString()}" th:lang-direction="#{language.direction}" xmlns:th="http://www.thymeleaf.org">
+
+<th:block th:insert="~{fragments/common :: head(title=#{removeBlanks.title})}"></th:block>
+
+
+<body>
+  <div id="page-container">
+    <div id="content-wrap">
+      <div th:insert="~{fragments/navbar.html :: navbar}"></div>
+      <br> <br>
+      <div class="container">
+        <div class="row justify-content-center">
+          <div class="col-md-6">
+            <h2 th:text="#{removeBlanks.header}"></h2>
+
+            <form id="multiPdfForm" th:action="@{remove-blanks}" method="post" enctype="multipart/form-data">
+              <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multiple=false, accept='application/pdf')}"></div>
+              <button type="submit" id="submitBtn" class="btn btn-primary" th:text="#{removeBlanks.submit}"></button>
+            </form>
+          </div>
+        </div>
+      </div>
+    </div>
+    <div th:insert="~{fragments/footer.html :: footer}"></div>
+  </div>
+</body>
+</html>