Use PNG Format Instead of JPEG for Screenshots

When I try to capture an image using the browser's internal "screenshot" function, I find that the resulting image is in JPEG format. Both "Capture area" and "Capture full page". This format is blurry, which is fine for photos, but for screenshots, the loss of image quality is fatal. I would have preferred to use the PNG format. At least in the Canary version, this little nuisance exists.