How to make jpeg progressive?

[b1rdex]

I see it in source, but how it works with default settings? Is it applied for all files or not? How do I force it to be always used?

[JayXon]

The default is progressive, but if it does not decrease file size then we keep the original, or if it's a small file and baseline is better than progressive then we use baseline. There isn't an option to force progressive because we always prefer whatever that gives smaller file size.

[b1rdex]

That's sad because progressive is always bigger AFAIK. I'm not too good in c++, can you please help me with patch to force progressive for files bigger that 10KB? I'll try to say why: I'm using Leanify to process images for web site and progressive jpeg is a must for web images.

[JayXon]

Are you sure? I think progressive is usually smaller for large images, and baseline is usually smaller for small images, for websites I think using baseline for small images is totally fine. If progressive is an absolute must for all images, then I would suggest to use mozjpeg and manually specify the options to force progressive.