Express.js missing ) after argument list

I have some code:

doc.image('images/pic_1.jpg', 0, 15, scale: 0.25)
    .text('Scale', 0, 0)

Based on official PDFkit documentation: PDFKit documentation But, this didn't work, and node console show me this, error, and underline "scale:0.25" part:

doc.image('images/pic_1.jpg', 0, 15, scale: 0.25) SyntaxError: missing ) after argument list

via Michaell94