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Java Advanced Imaging: resizing tiffs

Tue, 03/21/2006 - 17:09 — Frits Jalvingh

The Java Advanced Imaging toolkit contains lots of stuff to work with images. The documentation leaves a lot to be desired though: it is often factually incorrect due to version differences, and examples for common operations are hard to come by.

I needed a way to "resize" monochrome tiffs. The default "scale" operation leaves the result as a black-and-white image, and this results in a reduced image with a lousy quality. To get a better quality the image must be converted to grayscale and then rescaled using a resampler filter.

Most examples tell you to use either the "ColorConvert" or the "BandCombine" JAI operations. But sadly all of the examples I tried threw exceptions at one part or another.

Luckily though an operator exists which does exactly what we need: "subsampleBinaryToGray". To convert you use the following code:


File f = new File("blabla.tiff"); SeekableStream ss = new FileSeekableStream(f); RenderedImage ri = null; TIFFDecodeParam tp = null; ImageDecoder dec = ImageCodec.createImageDecoder("tiff", ss, tp); ri = dec.decodeAsRenderedImage(1); // Get 1st tiff image TiledImage tim = new TiledImage(ri, 512, 512); ri = tim; ParameterBlock pb = new ParameterBlock(); pb.addSource(ri); pb.add(scale); pb.add(scale); ImageLayout la = new ImageLayout(); la.setTileWidth(512); la.setTileHeight(512); RenderingHints rhi = new RenderingHints(JAI.KEY_IMAGE_LAYOUT, la); RenderedImage sri = JAI.create("subsampleBinaryToGray", pb, rhi);

Comments

Mon, 01/15/2007 - 04:39 — HexUzHoNG (not verified)

thanks for article i

thanks for article i want use this code resize tiff, but generate size is original tiff width, height. // scale value ? s = new FileSeekableStream(file); ImageDecoder dec = ImageCodec.createImageDecoder("tiff", s, param); int numofpages = dec.getNumPages(); for (int i = 0; i < numofpages; i++) { op = dec.decodeAsRenderedImage(i); TiledImage tim = new TiledImage(op, 512, 512); op = tim; ParameterBlock pb = new ParameterBlock(); pb.addSource(op); pb.add(512); // scale ? pb.add(512); // scale ? ImageLayout la = new ImageLayout(); la.setTileWidth(512); la.setTileHeight(512); RenderingHints rhi = new RenderingHints(JAI.KEY_IMAGE_LAYOUT, la); RenderedImage sri = JAI.create("subsampleBinaryToGray", pb, rhi); JAI.create("filestore", sri, imageDir + simplefilename + "." + i + ".png", "png"); }
Wed, 04/09/2008 - 13:15 — Anonymous

scale value ? s = new

scale value ? s = new FileSeekableStream(file); ImageDecoder dec = ImageCodec.createImageDecoder("tiff", s, param); int numofpages = dec.getNumPages(); for (int i = 0; i < numofpages; i++) { op = dec.decodeAsRenderedImage(i); TiledImage tim = new TiledImage(op, 512, 512); op = tim; ParameterBlock pb = new ParameterBlock(); pb.addSource(op); pb.add(512); // scale ? pb.add(512); // scale ? ImageLayout la = new ImageLayout(); la.setTileWidth(512); la.setTileHeight(512); RenderingHints rhi = new RenderingHints(JAI.KEY_IMAGE_LAYOUT, la); RenderedImage sri = JAI.create("subsampleBinaryToGray", pb, rhi); JAI.create("filestore", sri, imageDir + simplefilename + "." + i + ".png", "png"); } :sick: :sick: :jawdrop: 8) :O :P :)

how did u guyz use dis code man?.

Thu, 02/28/2008 - 14:51 — Anonymous

Thanks!

¡It worked really great! ¡Thanks!