[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[ft-devel] Speeding up PNG loading

From: Behdad Esfahbod
Subject: [ft-devel] Speeding up PNG loading
Date: Wed, 9 Aug 2017 15:56:02 -0700


I thought I see if I can speed up PNG loading by vectorizing alpha premultiplication, and it actually does give a nice speedup:

commit d7d592b0acb25ad8084b1d60459dd40bfd9c3356 (HEAD -> png-faster, github/png-faster)
Author: Behdad Esfahbod <address@hidden>
Date:   Tue Aug 8 21:29:25 2017 -0700

    Process four pixels at a time in premultiply_data() PNG function
    Load/store using memcpy().  Now this is finally faster than the non-vectorized
    code.  The premultiply_data() overhead is reduced by 60%.
    Numbers for:
    $ ftbench -b a ~/.fonts/NotoColorEmoji.ttf
    Without premultiply_data:       155 us/op
    With 4-pixel vectorization:     167 us/op <---------
    Without vectorization:          182 us/op

Code here:

The code is rather terse but readable.  I can add comments.  Needs some GCC/clang checks, as well as implementing the big-endian case (or disable it for big-endian).  I couldn't find any endianness macros in FreeType.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]