Re: [Freetype-devel] Difference in rendering

[Alexei Podtelezhnikov]

On Sun, May 23, 2021 at 7:06 AM Sarthak Bhardwaj
<1sarthakbhardwaj@gmail.com> wrote:
>
> Hello Suzuki,
>
> I believe you misunderstood me, I meant I have a program for highlighting 
> differences in images, I wanted to test what would happen in a regression 
> scenario, so wanted to know how to create a regression/difference in 
> freetype's rendering output.
>
> Thanks
> Sarthak
>

There are so many places: rounding errors in scaling, multiple hinting
algorithms, curve flattening during rendering to name few. Here is one
line in the code to mess things up:
https://gitlab.freedesktop.org/freetype/freetype/-/blob/master/src/smooth/ftgrays.c#L1041

Change that to ONE_PIXEL / 3, and all TrueType curves will look
slightly different, slightly worse.

Alexei