NIHVIVO-2477 Change the sequence of operations so scaling is done before cropping, thus avoiding the boundary conditions on rounding error. Use Java AWT operations to do scaling and cropping since the JAI operations are buggy. JAI is still used to read the file and to remove transparency.
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j2blake
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753545eb68
commit
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1 changed files with 82 additions and 45 deletions
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@ -2,24 +2,23 @@
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package edu.cornell.mannlib.vitro.webapp.controller.freemarker;
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import java.awt.geom.AffineTransform;
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import java.awt.image.AffineTransformOp;
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import java.awt.image.BufferedImage;
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import java.awt.image.ColorModel;
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import java.io.ByteArrayInputStream;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import javax.media.jai.InterpolationBilinear;
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import javax.imageio.ImageIO;
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import javax.media.jai.RenderedOp;
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import javax.media.jai.operator.BandSelectDescriptor;
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import javax.media.jai.operator.CropDescriptor;
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import javax.media.jai.operator.EncodeDescriptor;
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import javax.media.jai.operator.ScaleDescriptor;
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import javax.media.jai.operator.StreamDescriptor;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import com.sun.media.jai.codec.JPEGEncodeParam;
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import com.sun.media.jai.codec.MemoryCacheSeekableStream;
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import edu.cornell.mannlib.vitro.webapp.controller.freemarker.ImageUploadController.CropRectangle;
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@ -28,9 +27,19 @@ import edu.cornell.mannlib.vitro.webapp.controller.freemarker.ImageUploadControl
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* Crop the main image as specified, and scale it to the correct size for a
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* thumbnail.
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*
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* The JAI library has a problem when writing a JPEG from a source image with an
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* alpha channel (transparency). The colors come out inverted. We throw in a
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* step that will remove transparency from a PNG, but it won't touch a GIF.
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* Use the JAI library to read the file because the javax.imageio package
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* doesn't read extended JPEG properly. Use JAI to remove transparency from
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* JPEGs and PNGs, simply by removing the alpha channel. Annoyingly, this will
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* not work with GIFs with transparent pixels.
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*
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* The transforms in the JAI library are buggy, so standard AWT operations do
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* the scaling and cropping. The most obvious problem in the JAI library is the
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* refusal to crop after scaling an image.
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*
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* Scale first to avoid the boundary error that produces black lines along the
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* edge of the image.
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*
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* Use the javax.imagio pacakge to write the thumbnail image as a JPEG file.
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*/
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public class ImageUploadThumbnailer {
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/** If an image has 3 color bands and 1 alpha band, we want these. */
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@ -59,15 +68,42 @@ public class ImageUploadThumbnailer {
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try {
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RenderedOp mainImage = loadImage(mainImageStream);
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RenderedOp opaqueImage = makeImageOpaque(mainImage);
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RenderedOp croppedImage = cropImage(opaqueImage, crop);
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RenderedOp scaledImage = scaleImage(croppedImage);
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byte[] jpegBytes = encodeAsJpeg(scaledImage);
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BufferedImage bufferedImage = opaqueImage.getAsBufferedImage();
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log.debug("initial image: " + imageSize(bufferedImage));
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log.debug("initial crop: " + crop);
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CropRectangle boundedCrop = limitCropRectangleToImageBounds(
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bufferedImage, crop);
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log.debug("bounded crop: " + boundedCrop);
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float scaleFactor = figureScaleFactor(boundedCrop);
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log.debug("scale factor: " + scaleFactor);
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BufferedImage scaledImage = scaleImage(bufferedImage, scaleFactor);
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log.debug("scaled image: " + imageSize(scaledImage));
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CropRectangle rawScaledCrop = adjustCropRectangleToScaledImage(
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boundedCrop, scaleFactor);
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log.debug("scaled crop: " + rawScaledCrop);
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CropRectangle scaledCrop = limitCropRectangleToImageBounds(
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scaledImage, rawScaledCrop);
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log.debug("bounded scaled crop: " + scaledCrop);
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BufferedImage croppedImage = cropImage(scaledImage, scaledCrop);
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log.debug("cropped image: " + imageSize(croppedImage));
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byte[] jpegBytes = encodeAsJpeg(croppedImage);
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return new ByteArrayInputStream(jpegBytes);
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} catch (Exception e) {
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throw new IllegalStateException("Failed to scale the image", e);
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}
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}
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private String imageSize(BufferedImage image) {
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return image.getWidth() + " by " + image.getHeight();
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}
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private RenderedOp loadImage(InputStream imageStream) {
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return StreamDescriptor.create(new MemoryCacheSeekableStream(
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imageStream), null, null);
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@ -91,37 +127,8 @@ public class ImageUploadThumbnailer {
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return image;
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}
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private RenderedOp cropImage(RenderedOp image, CropRectangle crop) {
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CropRectangle boundedCrop = limitCropRectangleToImageBounds(image, crop);
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return CropDescriptor.create(image, (float) boundedCrop.x,
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(float) boundedCrop.y, (float) boundedCrop.width,
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(float) boundedCrop.height, null);
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}
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private RenderedOp scaleImage(RenderedOp image) {
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float horizontalScale = ((float) thumbnailWidth)
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/ ((float) image.getWidth());
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float verticalScale = ((float) thumbnailHeight)
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/ ((float) image.getHeight());
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log.debug("Generating a thumbnail, scales: " + horizontalScale + ", "
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+ verticalScale);
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return ScaleDescriptor.create(image, horizontalScale, verticalScale,
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0.0F, 0.0F, new InterpolationBilinear(), null);
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}
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private byte[] encodeAsJpeg(RenderedOp image) throws IOException {
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JPEGEncodeParam encodeParam = new JPEGEncodeParam();
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encodeParam.setQuality(1.0F);
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ByteArrayOutputStream bytes = new ByteArrayOutputStream();
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EncodeDescriptor.create(image, bytes, "JPEG", encodeParam, null);
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return bytes.toByteArray();
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}
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private CropRectangle limitCropRectangleToImageBounds(RenderedOp image,
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private CropRectangle limitCropRectangleToImageBounds(BufferedImage image,
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CropRectangle crop) {
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log.debug("Generating a thumbnail, initial crop info: " + crop);
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int imageWidth = image.getWidth();
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int imageHeight = image.getHeight();
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@ -140,10 +147,40 @@ public class ImageUploadThumbnailer {
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int w = Math.max(MINIMUM_CROP_SIZE, Math.min(greatestW, crop.width));
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int h = Math.max(MINIMUM_CROP_SIZE, Math.min(greatestH, crop.height));
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CropRectangle bounded = new CropRectangle(x, y, h, w);
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log.debug("Generating a thumbnail, bounded crop info: " + bounded);
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return bounded;
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return new CropRectangle(x, y, h, w);
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}
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private float figureScaleFactor(CropRectangle boundedCrop) {
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float horizontalScale = ((float) thumbnailWidth)
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/ ((float) boundedCrop.width);
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float verticalScale = ((float) thumbnailHeight)
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/ ((float) boundedCrop.height);
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return Math.min(horizontalScale, verticalScale);
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}
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private BufferedImage cropImage(BufferedImage image, CropRectangle crop) {
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return image.getSubimage(crop.x, crop.y, crop.width, crop.height);
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}
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private BufferedImage scaleImage(BufferedImage image, float scaleFactor) {
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AffineTransform transform = AffineTransform.getScaleInstance(
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scaleFactor, scaleFactor);
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AffineTransformOp atoOp = new AffineTransformOp(transform, null);
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return atoOp.filter(image, null);
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}
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private CropRectangle adjustCropRectangleToScaledImage(CropRectangle crop,
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float scaleFactor) {
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int newX = (int) (crop.x * scaleFactor);
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int newY = (int) (crop.y * scaleFactor);
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int newHeight = (int) (crop.height * scaleFactor);
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int newWidth = (int) (crop.width * scaleFactor);
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return new CropRectangle(newX, newY, newHeight, newWidth);
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}
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private byte[] encodeAsJpeg(BufferedImage image) throws IOException {
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ByteArrayOutputStream bytes = new ByteArrayOutputStream();
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ImageIO.write(image, "JPG", bytes);
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return bytes.toByteArray();
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}
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}
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