feat(replace-and-invert-colour): Add CMYK color space conversion with prepress preset for PDF processing (#4494)

app/common/src/main/java/stirling/software/common/model/api/misc/ReplaceAndInvert.java

@@ -4,4 +4,5 @@ public enum ReplaceAndInvert {
     HIGH_CONTRAST_COLOR,
     CUSTOM_COLOR,
     FULL_INVERSION,
+    COLOR_SPACE_CONVERSION,
 }

app/common/src/main/java/stirling/software/common/util/misc/ColorSpaceConversionStrategy.java

@@ -0,0 +1,94 @@
+package stirling.software.common.util.misc;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.core.io.InputStreamResource;
+import org.springframework.web.multipart.MultipartFile;
+
+import lombok.extern.slf4j.Slf4j;
+
+import stirling.software.common.model.api.misc.ReplaceAndInvert;
+import stirling.software.common.util.ProcessExecutor;
+import stirling.software.common.util.ProcessExecutor.ProcessExecutorResult;
+
+@Slf4j
+public class ColorSpaceConversionStrategy extends ReplaceAndInvertColorStrategy {
+
+    public ColorSpaceConversionStrategy(MultipartFile file, ReplaceAndInvert replaceAndInvert) {
+        super(file, replaceAndInvert);
+    }
+
+    @Override
+    public InputStreamResource replace() throws IOException {
+        Path tempInputFile = null;
+        Path tempOutputFile = null;
+
+        try {
+            tempInputFile = Files.createTempFile("colorspace_input_", ".pdf");
+            tempOutputFile = Files.createTempFile("colorspace_output_", ".pdf");
+
+            Files.write(tempInputFile, getFileInput().getBytes());
+
+            log.info("Starting CMYK color space conversion");
+
+            List<String> command = new ArrayList<>();
+            command.add("gs");
+            command.add("-sDEVICE=pdfwrite");
+            command.add("-dCompatibilityLevel=1.5");
+            command.add("-dPDFSETTINGS=/prepress");
+            command.add("-dNOPAUSE");
+            command.add("-dQUIET");
+            command.add("-dBATCH");
+            command.add("-sProcessColorModel=DeviceCMYK");
+            command.add("-sColorConversionStrategy=CMYK");
+            command.add("-sColorConversionStrategyForImages=CMYK");
+            command.add("-sOutputFile=" + tempOutputFile.toString());
+            command.add(tempInputFile.toString());
+
+            log.debug("Executing Ghostscript command for CMYK conversion: {}", command);
+
+            ProcessExecutorResult result =
+                    ProcessExecutor.getInstance(ProcessExecutor.Processes.GHOSTSCRIPT)
+                            .runCommandWithOutputHandling(command);
+
+            if (result.getRc() != 0) {
+                log.error(
+                        "Ghostscript CMYK conversion failed with return code: {}. Output: {}",
+                        result.getRc(),
+                        result.getMessages());
+                throw new IOException(
+                        "CMYK color space conversion failed: " + result.getMessages());
+            }
+
+            log.info("CMYK color space conversion completed successfully");
+
+            byte[] pdfBytes = Files.readAllBytes(tempOutputFile);
+            return new InputStreamResource(new ByteArrayInputStream(pdfBytes));
+
+        } catch (Exception e) {
+            log.warn("CMYK color space conversion failed", e);
+            throw new IOException(
+                    "Failed to convert PDF to CMYK color space: " + e.getMessage(), e);
+        } finally {
+            if (tempInputFile != null) {
+                try {
+                    Files.deleteIfExists(tempInputFile);
+                } catch (IOException e) {
+                    log.warn("Failed to delete temporary input file: {}", tempInputFile, e);
+                }
+            }
+            if (tempOutputFile != null) {
+                try {
+                    Files.deleteIfExists(tempOutputFile);
+                } catch (IOException e) {
+                    log.warn("Failed to delete temporary output file: {}", tempOutputFile, e);
+                }
+            }
+        }
+    }
+}

app/core/src/main/java/stirling/software/SPDF/Factories/ReplaceAndInvertColorFactory.java

@@ -5,6 +5,7 @@ import org.springframework.web.multipart.MultipartFile;
 
 import stirling.software.common.model.api.misc.HighContrastColorCombination;
 import stirling.software.common.model.api.misc.ReplaceAndInvert;
+import stirling.software.common.util.misc.ColorSpaceConversionStrategy;
 import stirling.software.common.util.misc.CustomColorReplaceStrategy;
 import stirling.software.common.util.misc.InvertFullColorStrategy;
 import stirling.software.common.util.misc.ReplaceAndInvertColorStrategy;
@@ -19,21 +20,17 @@ public class ReplaceAndInvertColorFactory {
             String backGroundColor,
             String textColor) {
 
-        if (replaceAndInvertOption == ReplaceAndInvert.CUSTOM_COLOR
+        return switch (replaceAndInvertOption) {
-                || replaceAndInvertOption == ReplaceAndInvert.HIGH_CONTRAST_COLOR) {
+            case CUSTOM_COLOR, HIGH_CONTRAST_COLOR ->
-
+                    new CustomColorReplaceStrategy(
-            return new CustomColorReplaceStrategy(
+                            file,
-                    file,
+                            replaceAndInvertOption,
-                    replaceAndInvertOption,
+                            textColor,
-                    textColor,
+                            backGroundColor,
-                    backGroundColor,
+                            highContrastColorCombination);
-                    highContrastColorCombination);
+            case FULL_INVERSION -> new InvertFullColorStrategy(file, replaceAndInvertOption);
-
+            case COLOR_SPACE_CONVERSION ->
-        } else if (replaceAndInvertOption == ReplaceAndInvert.FULL_INVERSION) {
+                    new ColorSpaceConversionStrategy(file, replaceAndInvertOption);
-
+        };
-            return new InvertFullColorStrategy(file, replaceAndInvertOption);
-        }
-
-        return null;
     }
 }

app/core/src/main/java/stirling/software/SPDF/config/EndpointConfiguration.java

@@ -400,6 +400,7 @@ public class EndpointConfiguration {
         /* Ghostscript */
         addEndpointToGroup("Ghostscript", "repair");
         addEndpointToGroup("Ghostscript", "compress-pdf");
+        addEndpointToGroup("Ghostscript", "replace-invert-pdf");
 
         /* tesseract */
         addEndpointToGroup("tesseract", "ocr-pdf");

app/core/src/main/java/stirling/software/SPDF/controller/api/misc/ReplaceAndInvertColorController.java

@@ -31,8 +31,8 @@ public class ReplaceAndInvertColorController {
     @Operation(
             summary = "Replace-Invert Color PDF",
             description =
-                    "This endpoint accepts a PDF file and option of invert all colors or replace"
+                    "This endpoint accepts a PDF file and provides options to invert all colors, replace"
-                            + " text and background colors. Input:PDF Output:PDF Type:SISO")
+                            + " text and background colors, or convert to CMYK color space for printing. Input:PDF Output:PDF Type:SISO")
     public ResponseEntity<InputStreamResource> replaceAndInvertColor(
             @ModelAttribute ReplaceAndInvertColorRequest request) throws IOException {
 

app/core/src/main/java/stirling/software/SPDF/model/api/misc/ReplaceAndInvertColorRequest.java

@@ -17,7 +17,12 @@ public class ReplaceAndInvertColorRequest extends PDFFile {
             description = "Replace and Invert color options of a pdf.",
             requiredMode = Schema.RequiredMode.REQUIRED,
             defaultValue = "HIGH_CONTRAST_COLOR",
-            allowableValues = {"HIGH_CONTRAST_COLOR", "CUSTOM_COLOR", "FULL_INVERSION"})
+            allowableValues = {
+                "HIGH_CONTRAST_COLOR",
+                "CUSTOM_COLOR",
+                "FULL_INVERSION",
+                "COLOR_SPACE_CONVERSION"
+            })
     private ReplaceAndInvert replaceAndInvertOption;
 
     @Schema(

app/core/src/main/resources/messages_en_GB.properties

@@ -878,6 +878,12 @@ replace-color.selectText.8=Yellow text on black background
 replace-color.selectText.9=Green text on black background
 replace-color.selectText.10=Choose text Colour
 replace-color.selectText.11=Choose background Colour
+replace-color.selectText.12=Colour Space Conversion (CMYK for Printing)
+replace-color.selectText.13=CMYK Colour Space Conversion
+replace-color.selectText.14=This option converts the PDF from RGB colour space to CMYK colour space, which is optimized for professional printing. This process:
+replace-color.selectText.15=Converts colours to CMYK (Cyan, Magenta, Yellow, Black) colour model used by professional printers
+replace-color.selectText.16=Optimizes the PDF for print production with prepress settings
+replace-color.selectText.17=May result in slight colour changes as CMYK has a smaller colour gamut than RGB
 replace-color.submit=Replace
 
 

app/core/src/main/resources/templates/misc/replace-color.html

@@ -30,6 +30,7 @@
                                     <option value="HIGH_CONTRAST_COLOR" th:text="#{replace-color.selectText.2}" ></option>
                                     <option value="CUSTOM_COLOR" th:text="#{replace-color.selectText.3}"></option>
                                     <option value="FULL_INVERSION" th:text="#{replace-color.selectText.4}" selected></option>
+                                    <option th:text="#{replace-color.selectText.12}" value="COLOR_SPACE_CONVERSION"></option>
                                 </select>
                             </div>
                         </div>
@@ -57,6 +58,18 @@
                             </div>
                         </div>
                         
+                        <div class="card mb-3" id="color-space-info" style="display: none">
+                            <div class="card-body">
+                                <h4 th:text="#{replace-color.selectText.13}"></h4>
+                                <p th:text="#{replace-color.selectText.14}"></p>
+                                <ul>
+                                    <li th:text="#{replace-color.selectText.15}"></li>
+                                    <li th:text="#{replace-color.selectText.16}"></li>
+                                    <li th:text="#{replace-color.selectText.17}"></li>
+                                </ul>
+                            </div>
+                        </div>
+
                         <button type="submit" id="submitBtn" class="btn btn-primary" th:text="#{replace-color.submit}"></button>
                     </form>
                 </div>
@@ -74,12 +87,15 @@
             $('#high-contrast-options').hide();
             $('#custom-color-1').hide();
             $('#custom-color-2').hide();
+            $('#color-space-info').hide();
 
             if (selectedOption === "HIGH_CONTRAST_COLOR") {
                 $('#high-contrast-options').show();
             } else if (selectedOption === "CUSTOM_COLOR") {
                 $('#custom-color-1').show();
                 $('#custom-color-2').show();
+            } else if (selectedOption === "COLOR_SPACE_CONVERSION") {
+                $('#color-space-info').show();
             }
         });
     });