On Sun, 28 Dec 2025 02:22:16 GMT, Jeremy Wood <[email protected]> wrote:
> When decoding an uninterlaced 8-bit PNG image, the PNGImageDecoder is > basically copying one byte at a time. > > This PR uses System.arraycopy instead, and it shows approx a 10% improvement. > > This graph shows the time it takes different decoders to convert a byte array > into a BufferedImage as the size of the PNG image increases: > > <img width="596" height="366" alt="Screenshot 2025-12-27 at 9 14 19 PM" > src="https://github.com/user-attachments/assets/73583cb2-eda0-47a8-b818-735a1835f1e8"; > /> > > (This originally came to my attention when looking at an image in Java 1.8. > There the ImageConsumer model took approx 400% longer than ImageIO. I was > happy to see in recent JDKs that gap narrowed significantly, but there was > still a noticeable 10% discrepancy.) > > I haven't tried submitting a performance enhancement PR before; I'm not sure > if this issue meets this group's threshold for being worth addressing. And if > it does: I'm not sure how to structure a unit test for it. This pull request has now been integrated. Changeset: 2a965dff Author: Jeremy Wood <[email protected]> Committer: Jayathirth D V <[email protected]> URL: https://git.openjdk.org/jdk/commit/2a965dffdd2791ab87a2dbfba8ed44f8adb996c7 Stats: 400 lines in 3 files changed: 396 ins; 0 del; 4 mod 8374377: PNGImageDecoder Slow For 8-bit PNGs Reviewed-by: jdv, prr ------------- PR: https://git.openjdk.org/jdk/pull/29004
