问题
Use canvas.toDataURL('image/jpeg', 1) in Chrome, the image is lose a little seriously, but in Firefox, It's ok, almost lossless, even use default quality value 0.92. It seems does not working by setting the quality in Chrome.
回答1:
It's a known issue and it's due to how chroma subsampling is handled.
Chrome do this differently than Firefox and Safari. The latter ones uses 4:4:4 at 1.0 setting while current Chrome doesn't. However, it seem as the latest Canary (version 33) do the same as the others.
In any case, until it has been solved it's very little you and I can do about it unfortunately...
来源：https://stackoverflow.com/questions/20278017/chrome-todataurl-quality-param-is-not-effect-when-export-jpeg