Hello,
The com.sun.imageio.plugins.png.PNGImageReader was updated during one
of the jdk1.6 releases (I think the change happened in jdk1.6_14).
One of the changes that I noticed caused some performance impact when
generating PS with a PNG image in FOP is this one in the
getImageTypes() method:
case PNG_COLOR_RGB:
if (bitDepth == 8) {
// some standard types of buffered images
// which can be used as destination
l.add(ImageTypeSpecifier.createFromBufferedImageType(
BufferedImage.TYPE_3BYTE_BGR));
l.add(ImageTypeSpecifier.createFromBufferedImageType(
BufferedImage.TYPE_INT_RGB));
l.add(ImageTypeSpecifier.createFromBufferedImageType(
BufferedImage.TYPE_INT_BGR));
}
// Component R, G, B
rgb = ColorSpace.getInstance(ColorSpace.CS_sRGB);
The if (bitDepth ==8) {} code is new. There is similar new code for
PNG_COLOR_RGB_ALPHA.
This new code is executed for some PNG images and the result is seen
in the
org.apache.xmlgraphics.ps.ImageEncodingHelper.determineEncodedColorModel()
method:
int[] offsets = piSampleModel.getBandOffsets();
for (int i = 0; i < offsets.length; i++) {
if (offsets[i] != i ) {
//Don't encode directly as samples are not
next to each other
//i.e. offsets are not 012 (RGB) or 0123 (CMYK)
return;
}
}
The offsets come as [2, 1, 0] instead of [0, 1, 2] so the above code
returns. As result, the encode() method in the same class:
public void encode(OutputStream out) throws IOException {
if (!isConverted()) {
if (optimizedWriteTo(out)) {
return;
}
}
writeRGBTo(out);
}
follows the writeRGBTo() path instead of the previous
optimizedWriteTo() path. The end result is a 40% performance impact
for the PNG file I have been testing with when going from jdk1.6_13 to
a more recent one, like jdk1.6_30.
Any ideas on how to recover the previous performance (i.e., use the
optimizedWriteTo() path)?
Luis
