feat: opt-in JPEG-embed quality for image-to-PDF conversion

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/converters/imageToPdf.js

@@ -5,13 +5,17 @@ import { register } from './registry.js';
 
 const IMAGE_FORMATS = ['jpg', 'jpeg', 'png', 'webp', 'gif', 'tiff', 'avif'];
 
-async function convert(inputPath, outputPath) {
+async function convert(inputPath, outputPath, { quality } = {}) {
-  const pngBuffer = await sharp(inputPath).png().toBuffer();
+  const imageBuffer =
-  const metadata = await sharp(pngBuffer).metadata();
+    quality == null
+      ? await sharp(inputPath).png().toBuffer()
+      : await sharp(inputPath).jpeg({ quality }).toBuffer();
+  const metadata = await sharp(imageBuffer).metadata();
 
   const pdfDoc = await PDFDocument.create();
   const page = pdfDoc.addPage([metadata.width, metadata.height]);
-  const embeddedImage = await pdfDoc.embedPng(pngBuffer);
+  const embeddedImage =
+    quality == null ? await pdfDoc.embedPng(imageBuffer) : await pdfDoc.embedJpg(imageBuffer);
 
   page.drawImage(embeddedImage, {
     x: 0,

test/converters/imageToPdf.test.js

@@ -2,6 +2,7 @@ import { describe, it, expect, beforeAll, afterAll } from 'vitest';
 import fs from 'node:fs/promises';
 import path from 'node:path';
 import os from 'node:os';
+import sharp from 'sharp';
 import { registerImageToPdfConverter } from '../../src/converters/imageToPdf.js';
 import { resolve, listTargetFormats } from '../../src/converters/registry.js';
 import { detectInputMime } from '../../src/mime.js';
@@ -33,4 +34,34 @@ describe('image to PDF converter', () => {
     const detected = await detectInputMime(outputPath);
     expect(detected.mime).toBe('application/pdf');
   });
+
+  it('embeds a JPEG instead of a PNG when a quality is given, shrinking the output for a noisy image', async () => {
+    const inputPath = path.join(tmpDir, 'noisy.png');
+    await sharp({
+      create: {
+        width: 256,
+        height: 256,
+        channels: 3,
+        noise: { type: 'gaussian', mean: 128, sigma: 40 },
+      },
+    })
+      .png()
+      .toFile(inputPath);
+
+    const defaultOutputPath = path.join(tmpDir, 'default.pdf');
+    const compressedOutputPath = path.join(tmpDir, 'compressed.pdf');
+    const entry = resolve('png', 'pdf');
+
+    await entry.convert(inputPath, defaultOutputPath);
+    await entry.convert(inputPath, compressedOutputPath, { quality: 20 });
+
+    const compressedDetected = await detectInputMime(compressedOutputPath);
+    expect(compressedDetected.mime).toBe('application/pdf');
+
+    const [defaultStat, compressedStat] = await Promise.all([
+      fs.stat(defaultOutputPath),
+      fs.stat(compressedOutputPath),
+    ]);
+    expect(compressedStat.size).toBeLessThan(defaultStat.size);
+  });
 });