How would you validate an uploaded image's actual dimensions and reject ones that don't meet minimum or maximum size requirements?

After the file is uploaded (but before accepting it as valid), you can use an image-processing library like sharp to read the image's actual metadata (width and height) and compare it against your application's requirements, rejecting and cleaning up the uploaded file if it doesn't meet the criteria, rather than relying solely on file-size limits which don't reflect actual image dimensions.

const sharp = require('sharp');

const metadata = await sharp(req.file.path).metadata();
if (metadata.width < 200 || metadata.height < 200) {
  await fs.promises.unlink(req.file.path); // clean up the rejected upload
  return res.status(400).json({ error: 'Image must be at least 200x200 pixels' });
}