{"action":"created","issue":{"url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/59","repository_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo","labels_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/59/labels{/name}","comments_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/59/comments","events_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/59/events","html_url":"https://github.com/libjpeg-turbo/libjpeg-turbo/issues/59","id":135316769,"number":59,"title":"\"Progressive mode\" is always \"optimized\" (Huffman)","user":{"login":"fireattack","id":4130991,"avatar_url":"https://avatars.githubusercontent.com/u/4130991?v=3","gravatar_id":"","url":"https://api.github.com/users/fireattack","html_url":"https://github.com/fireattack","followers_url":"https://api.github.com/users/fireattack/followers","following_url":"https://api.github.com/users/fireattack/following{/other_user}","gists_url":"https://api.github.com/users/fireattack/gists{/gist_id}","starred_url":"https://api.github.com/users/fireattack/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/fireattack/subscriptions","organizations_url":"https://api.github.com/users/fireattack/orgs","repos_url":"https://api.github.com/users/fireattack/repos","events_url":"https://api.github.com/users/fireattack/events{/privacy}","received_events_url":"https://api.github.com/users/fireattack/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/labels/question","name":"question","color":"cc317c"}],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2016-02-22T04:52:40Z","updated_at":"2016-02-22T16:55:58Z","closed_at":"2016-02-22T16:45:38Z","body":"Long in short, when using `cjpeg` or `jpegtran`, I found that when `-progressive ` switch is enabled, `-optimize` (Huffman) will always be applied too even when we don't use that parameter, i.e. using `-progressive` and `-progressive -optimize` will give out identical results (bit-accurate).\r\n\r\nAfter a quick search, I believe it's doing so because of https://github.com/libjpeg-turbo/libjpeg-turbo/blob/d4be42360c6c8a89309ffb0cc32041d799deb392/jcmaster.c#L606\r\n\r\nNow I was just curious (not questioning), what's the reason to do so? \r\n\r\nI found [this ](https://sourceforge.net/p/libjpeg-turbo/mailman/message/34534764/)relavant dicussion in the maillist but it didn't explain too much.\r\n\r\nCheers."},"comment":{"url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/comments/187264635","html_url":"https://github.com/libjpeg-turbo/libjpeg-turbo/issues/59#issuecomment-187264635","issue_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/59","id":187264635,"user":{"login":"fireattack","id":4130991,"avatar_url":"https://avatars.githubusercontent.com/u/4130991?v=3","gravatar_id":"","url":"https://api.github.com/users/fireattack","html_url":"https://github.com/fireattack","followers_url":"https://api.github.com/users/fireattack/followers","following_url":"https://api.github.com/users/fireattack/following{/other_user}","gists_url":"https://api.github.com/users/fireattack/gists{/gist_id}","starred_url":"https://api.github.com/users/fireattack/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/fireattack/subscriptions","organizations_url":"https://api.github.com/users/fireattack/orgs","repos_url":"https://api.github.com/users/fireattack/repos","events_url":"https://api.github.com/users/fireattack/events{/privacy}","received_events_url":"https://api.github.com/users/fireattack/received_events","type":"User","site_admin":false},"created_at":"2016-02-22T16:55:58Z","updated_at":"2016-02-22T16:55:58Z","body":"That answered my question. Thanks!"}}