On 23/07/2020 23:42, Lloyd wrote:
>
> Thanks a lot for your help.
>
>     Probably the important part is what your T() is.
>
> T is the format of the source file. In the case of jpeg, it is gil::jpeg_tag

That means you're using 100% quality by default.  To reduce the file
size you'd have to change this, as I said.

>     When calling write_view, you can specify a JPEG quality explicitly via
>     something like image_write_info<jpeg_tag>(95) -- use a lower number for
>     a smaller file size but more artifacting.
>
>     If you don't specify it, GIL uses 100 by default (which might be
>     excessive).  Other editors probably use different values by default,
>     which might be causing the file size increase you're seeing.
>
>
> May i know what do you mean by "Other editors" ?

Whatever image editor that originally created or last edited the file.