setup a conversion script to debug sharp source code and fix issue lo…

…vell#4045

nodemon.json

@@ -2,5 +2,5 @@
   "watch": ["src/**/*.cc", "src/**/*.h", "printlane/convert.js"],
   "ext": "cc",
   "verbose": false,
-  "exec": "npm i --build-from-source && clear && node printlane/convert.js"
+  "exec": "clear && npm i --build-from-source && clear && node printlane/convert.js"
 }

printlane/convert.js

@@ -1,34 +1,85 @@
 const sharp = require('../lib');
-const icc = require('icc');
 const { resolve: pathResolve } = require('path');
 const assert = require('assert');
+const spawnChild = require('./utils/spawnChild');
 
 // Define input and output files
-const inFile = pathResolve(__dirname, 'files/sticker.jpg');
-const outFile = pathResolve(__dirname, 'files/sticker-OUT.jpg');
+const inFile = pathResolve(__dirname, 'files/100-0-0-100-fogra.tif');
+const swop = pathResolve(__dirname, 'files/swop.icc');
 
-(async function main () {
-  console.log('HALLO1', inFile);
+// Helper to get a pixel value (uses `vips`, install with `brew install vips`)
+async function getPixelValues(fileName, x, y) {
+  const data = await spawnChild(
+    'vips',
+    [
+      `getpoint`,
+      `${fileName}`,
+      `${x}`, // pixel x
+      `${y}`, // pixel y
+    ],
+  );
+
+  // Remove linebreaks and trim spaces from output and return (output is a string, e.g. '255 128 0 0`)
+  return data.replace(/\n/g, '').trim();
+}
 
-  // Get ICC profile from inFile
-  const metaInFile = await sharp(inFile).metadata();
-  assert.ok(metaInFile.icc instanceof Buffer, 'icc not set in inFile');
-  const { description: iccDescrInFile } = icc.parse(metaInFile.icc);
+// Helper to validate if a pixel equals to specific values (uses `vips`, install with `brew install vips`)
+async function validatePixelValues(fileName, expectedPixelValues) {
+  for (let i = 0; i < 10; i += 1) {
+    const pixelValues = await getPixelValues(fileName, i, i);
+    assert.strictEqual(pixelValues, expectedPixelValues);
+  }
+}
 
-  // Convert, keep ICC from inFile
+// Main function
+(async function main () {
+  // ##############################################################################
+  // Invert without color space change (WORKING)
+  // ##############################################################################
+  // Source file: 1000x1000 file with CMYK colors 0/100/100/0 in Coated Fogra39
+  await validatePixelValues(inFile, '255 0 0 255');
+  const outFileFogra = pathResolve(__dirname, 'files/0-100-100-0-fogra.tif');
   await sharp(inFile)
-    .pipelineColourspace('cmyk')
     .toColourspace('cmyk')
+    .pipelineColourspace('cmyk')
     .keepIccProfile()
-    .toFile(outFile);
+    .negate()
+    .toFile(outFileFogra);
+  await validatePixelValues(outFileFogra, '0 255 255 0');
+  // Output file: 1000x1000 file with CMYK colors 100/0/0/100 (inverted) in Coated Fogra39
 
-  // Extract metadata from outFile, assert icc profile is present
-  const metaOutFile = await sharp(outFile).metadata();
-  assert.ok(metaOutFile.icc instanceof Buffer, 'icc not set in outFile');
+  // ##############################################################################
+  // Invert with color space change in 2 steps (WORKING)
+  // ##############################################################################
+  const outFileSwop2 = pathResolve(__dirname, 'files/218-187-153-197-swop.tif');
+  await sharp(inFile)
+    .toColourspace('cmyk')
+    .pipelineColourspace('cmyk')
+    .withIccProfile(swop)
+    .toFile(outFileSwop2);
+  await validatePixelValues(outFileSwop2, '218 187 153 197');
+  // Output file: 1000x1000 file with CMYK colors 218/187/153/197 in U.S. Web Coated Swop V2
 
-  // Check if description of ICC profile in output file matches description of ICC profile in input file
-  const { description: iccDescrOutFile } = icc.parse(metaOutFile.icc);
-  assert.strictEqual(iccDescrOutFile, iccDescrInFile);
+  const outFileSwopInverted2Steps = pathResolve(__dirname, 'files/37-68-102-58-swop-inverted-2step.tif');
+  await sharp(outFileSwop2)
+    .toColourspace('cmyk')
+    .pipelineColourspace('cmyk')
+    .keepIccProfile()
+    .negate()
+    .toFile(outFileSwopInverted2Steps);
+  await validatePixelValues(outFileSwopInverted2Steps, `${255 - 218} ${255 - 187} ${255 - 153} ${255 - 197}`);
+  // Output file: 1000x1000 file with CMYK colors 37/68/102/58 in U.S. Web Coated Swop V2, so the values are inverted (resulting value = 255 - source value)
 
-  console.log('HALLO3', outFile);
+  // ##############################################################################
+  // Invert with color space change in 1 step (NOT WORKING)
+  // ##############################################################################
+  const outFileSwopInverted1Step = pathResolve(__dirname, 'files/37-68-102-58-swop-inverted-1step.tif');
+  await sharp(inFile)
+    .toColourspace('cmyk')
+    .pipelineColourspace('cmyk')
+    .withIccProfile(swop)
+    .negate()
+    .toFile(outFileSwopInverted1Step);
+  await validatePixelValues(outFileSwopInverted1Step, `${255 - 218} ${255 - 187} ${255 - 153} ${255 - 197}`);
+  // Output file: 1000x1000 file with CMYK colors 37/68/102/58 in U.S. Web Coated Swop V2, so the values are inverted (resulting value = 255 - source value)
 })();

printlane/utils/spawnChild.js

@@ -0,0 +1,71 @@
+const { spawn } = require('child_process');
+
+/**
+ * Spawns a child process to run a program with the specified arguments and environment variables.
+ *
+ * This asynchronous function uses Node.js's `spawn` from the `child_process` module to create a new child process.
+ * It optionally logs standard output and standard error streams based on the provided options.
+ *
+ * @param {string} programPath - The path to the program to execute.
+ * @param {Array<string>} args - Arguments to pass to the program.
+ * @param {Object} options - Options for the `spawn` command. Can include a key `env` to set environment variables
+ * @param {Object} opts - Options for logging standard output and error. Defaults to not logging either.
+ * @param {boolean} opts.logStdOut - Flag to log standard output. Default is false.
+ * @param {boolean} opts.logStdErr - Flag to log standard error. Default is false.
+ *
+ * @returns {Promise<string>} A promise that resolves with the standard output data from the child process
+ * or rejects with an error message if the child process exits with a non-zero exit code.
+ *
+ * @throws {Error} Throws an error with the standard error output if the child process exits with a non-zero exit code.
+ *
+ * @example
+ * // Example usage:
+ * spawnChild('path/to/program', ['arg1', 'arg2'], { ENV_VAR: 'value' }, { logStdOut: true, logStdErr: true })
+ *   .then(output => console.log(output))
+ *   .catch(error => console.error(error));
+ */
+module.exports = async function spawnChild(programPath, args, options = {}, opts = {
+  logStdOut: false,
+  logStdErr: false,
+}) {
+  // Spawn child
+  const child = spawn(
+    programPath,
+    args,
+    {
+      ...options,
+      env: {
+        ...process.env,
+        ...options.env,
+      },
+    },
+  );
+
+  // Gather data
+  let data = '';
+  for await (const chunk of child.stdout) {
+    if (opts.logStdOut) console.log(chunk.toString()); // eslint-disable-line no-console
+    data += chunk;
+  }
+
+  // Gather errors
+  let error = '';
+  for await (const chunk of child.stderr) {
+    if (opts.logStdErr) console.log(chunk.toString()); // eslint-disable-line no-console
+    error += chunk;
+  }
+
+  // Await for the program to exist
+  const exitCode = await new Promise((resolve) => {
+    child.on('close', resolve);
+  });
+
+  // Reject the promise if exit code > 0 (an error occurred)
+  if (exitCode) {
+    if (opts.logStdErr) console.log(`subprocess error exit ${exitCode}, ${error}`); // eslint-disable-line no-console
+    throw new Error(error);
+  }
+
+  // Return the data
+  return data;
+}