Hi guys, I do love optimizing java2d, so Ido support & sponsor your buffered image (ARGB PRE or not) changes.
Let's start a github project to start this concrete patch... as I did for the marlin renderer or we could use the marlin repository to host your changes to java.awt or java2d packages. See jdk (25?) branch: https://github.com/bourgesl/marlin-renderer/tree/jdk/src/main/java/sun/java2d Cheers, Laurent -- Laurent Bourgès Le ven. 22 août 2025, 14:04, Daniel Gredler <djgred...@gmail.com> a écrit : > Hi all, > > `BufferedImage.getRGB(int, int, int, int, int[], int, int)` is often used > for processing of individual image pixels. A common pattern is to loop > through each row of pixels, calling this method once per row to populate > the row pixel `int[]` and then process it. > > There are many types of `BufferedImage`, but one of the most common types > is `TYPE_INT_ARGB`. Based on a quick search on GitHub, about one third of > all BufferedImages are of this type [1]. This is also the representation > which `BufferedImage.getRGB(int, int, int, int, int[], int, int)` uses for > its output. > > I think there may be an opportunity here (in `BufferedImage.getRGB(int, > int, int, int, int[], int, int)`) to skip the pixel-by-pixel color model > conversion if the `BufferedImage` is already of type `TYPE_INT_ARGB`, which > is relatively common. See here [2] for what this optimization could look > like. > > In my local testing, a simple test program [3] went from running in 220 > seconds without the change to running in 7 seconds with the change. > Separately, a real-world program which uses the row-by-row pixel access > pattern went from running in 45 seconds to running in 29 seconds. > > Does this look like a good change to those of you who know this part of > the code? Am I missing something that might make this dangerous or > undesirable? Is it making too many assumptions? I know this area is fraught > with gotchas -- color models, color spaces, strides, etc. > > Thanks! > > Daniel > > --- > > [1] > BufferedImage.TYPE_CUSTOM: 2k > BufferedImage.TYPE_INT_RGB: 114k > BufferedImage.TYPE_INT_ARGB: 93k << 35% > BufferedImage.TYPE_INT_ARGB_PRE: 5k > BufferedImage.TYPE_INT_BGR: 4k > BufferedImage.TYPE_3BYTE_BGR: 10k > BufferedImage.TYPE_4BYTE_ABGR: 9k > BufferedImage.TYPE_4BYTE_ABGR_PRE: 2k > BufferedImage.TYPE_USHORT_565_RGB: 1k > BufferedImage.TYPE_USHORT_555_RGB: 1k > BufferedImage.TYPE_BYTE_GRAY: 11k > BufferedImage.TYPE_USHORT_GRAY: 2k > BufferedImage.TYPE_BYTE_BINARY: 5k > BufferedImage.TYPE_BYTE_INDEXED: 3k > Total: 262k > > [2] > https://github.com/gredler/jdk/commit/b98f6cdf7573b7e89067c757890193517aeb472e > > [3] > public final class PerfTest { > public static void main(final String[] args) { > int w = 1_000; > int h = 1_000; > int accumulator = 0; > BufferedImage image = new BufferedImage(w, h, > BufferedImage.TYPE_INT_ARGB); > int[] row = new int[w]; > long start = System.currentTimeMillis(); > for (int i = 0; i < 100_000; i++) { > for (int y = 0; y < h; y++) { > image.getRGB(0, y, w, 1, row, 0, w); > accumulator += row[i % w]; > } > } > long end = System.currentTimeMillis(); > System.out.println("Total time: " + ((end - start) / 1_000) + " > seconds"); > System.out.println("Accumulator: " + accumulator); > } > } > >
