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Re: Can you resize with BufferedImage

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On Wednesday, April 12, 2017 at 11:06:08 AM UTC-4, Knute Johnson wrote:
> On 4/12/2017 08:06, Martin Gregorie wrote:
> 
> If you find a good book, let us all know please.
> 
> I wrote a library to do a few common image mods so I don't have to 
> remember how to do it every time:
> 
> package com.knutejohnson.classes;
> 
> import java.awt.*;
> import java.awt.color.*;
> import java.awt.geom.*;
> import java.awt.image.*;
> import java.io.*;
> import java.util.*;
> import javax.imageio.*;
> import javax.imageio.stream.*;
> import javax.imageio.plugins.jpeg.*;
> 
> /**
>   * ImageUtilities is an assortment of static methods to manipulate
>   * BufferedImages
>   *
>   * @author Knute Johnson
>   */
> public class ImageUtilities {
>      /**
>       * Writes a BufferedImage to a JPEG file with the specified quality
>       *
>       * @param image     BufferedImage to write
>       * @param quality   image quality, a float value between 0.0f and 1.0f
>       * @param file      destination File
>       *
>       * @throws IOException if an error occurs writing to the file
>       * @throws IllegalArgumentException if quality is not in the range
>       *         0.0f to 1.0f
>       */
>      public static void writeJPEG(RenderedImage image, float quality, 
> File file)
>       throws IOException {
>          if (quality < 0.0f || quality > 1.0f)
>              throw new IllegalArgumentException("0.0 < Quality < 1.0");
>          ImageWriter writer = null;
>          Iterator iter = ImageIO.getImageWritersByFormatName("JPEG");
>          if (!iter.hasNext())
>              throw new IOException("No Writers Available");
>          writer = (ImageWriter)iter.next();
>          if (file.exists())
>              file.delete();
>          ImageOutputStream ios = ImageIO.createImageOutputStream(file);
>          writer.setOutput(ios);
>          JPEGImageWriteParam iwp = new JPEGImageWriteParam(null);
>          iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
>          iwp.setCompressionQuality(quality);
>          writer.write(null,new IIOImage(image,null,null),iwp);
>          ios.flush();
>          writer.dispose();
>          ios.close();
>      }
> 
>      /**
>       * Converts a colored image to gray scale
>       *
>       * @param image     source BufferedImage
>       * @param hints     any rendering hints for the conversion or 
> {@code null}
>       *
>       * @return          gray scale BufferedImage
>       */
>      public static BufferedImage convertToGray(BufferedImage image,
>       RenderingHints hints) {
>          BufferedImage gray =
>           createCompatible(image.getWidth(),image.getHeight());
> 
>          ColorConvertOp op = new ColorConvertOp(
>           image.getColorModel().getColorSpace(),
>           ColorSpace.getInstance(ColorSpace.CS_GRAY),hints);
> 
>          return op.filter(image,gray);
>      }
> 
>      /**
>       * Converts a color image to sepia tone
>       *
>       * @param image     source image
>       * @param hints     any rendering hints for the conversion or 
> {@code null}
>       *
>       * @return          sepia tone image
>       */
>      public static BufferedImage convertToSepia(BufferedImage image,
>       RenderingHints hints) {
>          BufferedImage sepia =
>           createCompatible(image.getWidth(),image.getHeight());
> 
>          // convert to grayscale and back to compatible RGB
>          ColorSpace imgCS = image.getColorModel().getColorSpace();
>          ColorSpace grayCS = ColorSpace.getInstance(ColorSpace.CS_GRAY);
>          ColorSpace sepiaCS = sepia.getColorModel().getColorSpace();
>          ColorConvertOp cop = new ColorConvertOp(imgCS,grayCS,hints);
>          image = cop.filter(image,null);
>          cop = new ColorConvertOp(grayCS,sepiaCS,hints);
>          sepia = cop.filter(image,null);
> 
>          // slightly enhance the red, slightly reduce the green and
>          // remove half the blue
>          float[] factor = new float[] { 1.35f,1f,.7f };
>          float[] offset = new float[] { 0f,0f,0f };
>          RescaleOp rop = new RescaleOp(factor,offset,hints);
> 
>          return rop.filter(sepia,null);
>      }
> 
>      /**
>       * Scales a BufferedImage
>       *
>       * @param src       source BufferedImage
>       * @param sx        x scale factor
>       * @param sy        y scale factor
>       * @param interpolationType the interpolation type
>       *
>       * @return          scaled BufferedImage
>       *
>       * @see AffineTransformOp
>       */
>      public static BufferedImage scaleImage(BufferedImage src, double sx,
>       double sy, int interpolationType) {
>          AffineTransformOp op = new AffineTransformOp(
>           AffineTransform.getScaleInstance(sx,sy),interpolationType);
> 
>          return op.filter(src,null);
>      }
> 
>      /**
>       * Scales a BufferedImage
>       *
>       * @param src       source BufferedImage
>       * @param sx        x scale factor
>       * @param sy        y scale factor
>       * @param hints     any rendering hints or {@code null}
>       *
>       * @return          scaled BufferedImage
>       *
>       * @see RenderingHints
>       */
>      public static BufferedImage scaleImage(BufferedImage src, double sx,
>       double sy, RenderingHints hints) {
>          AffineTransformOp op = new AffineTransformOp(
>           AffineTransform.getScaleInstance(sx,sy),hints);
> 
>          return op.filter(src,null);
>      }
> 
>      /**
>       * Creates a compatible BufferedImage with the specified dimensions
>       *
>       * @param width     width of the image
>       * @param height    height of the image
>       *
>       * @return          compatible BufferedImage
>       */
>      public static BufferedImage createCompatible(int width, int height) {
>          GraphicsConfiguration gc = getDefaultConfiguration();
> 
>          return gc.createCompatibleImage(width,height);
>      }
> 
>      /**
>       * Creates a compatible BufferedImage with the specified dimensions and
>       * transparency
>       *
>       * @param width         image width
>       * @param height        image height
>       * @param transparency  transparency of the image
>       *
>       * @return              compatible BufferedImage
>       *
>       * @see BufferedImage
>       * @see Transparency
>       */
>      public static BufferedImage createCompatible(int width, int height,
>       int transparency) {
>          GraphicsConfiguration gc = getDefaultConfiguration();
> 
>          return gc.createCompatibleImage(width,height,transparency);
>      }
> 
>      /**
>       * Converts an existing image to a compatible ColorModel
>       *
>       * @param image     source BufferedImage
>       * @param hints     any RenderingHints or {@code null}
>       *
>       * @return          compatible BufferedImage
>       *
>       * @see ColorModel
>       * @see RenderingHints
>       */
>      public static BufferedImage convertToCompatible(BufferedImage image,
>       RenderingHints hints) {
>          if (isCompatible(image))
>              return image;
> 
>          ColorConvertOp op = new ColorConvertOp(
>           image.getColorModel().getColorSpace(),
>           getDefaultConfiguration().getColorModel().getColorSpace(),hints);
> 
>          return op.filter(image,null);
>      }
> 
>      /**
>       * Converts an existing BufferedImage to a compatible ColorModel
>       *
>       * @param image     source BufferedImage
>       *
>       * @return          compatible BufferedImage
>       */
>      public static BufferedImage convertToCompatible(BufferedImage image) {
>          return convertToCompatible(image,null);
>      }
> 
>      /**
>       * Checks if a BufferedImage is compatible
>       *
>       * @param src           source BufferedImage
>       *
>       * @return              {@code true} if image is compatible
>       */
>      public static boolean isCompatible(BufferedImage src) {
>          GraphicsConfiguration gc = getDefaultConfiguration();
> 
>          return src.getColorModel().equals(gc.getColorModel());
>      }
> 
>      /**
>       * Gets the default graphics configuration.  Used by several methods in
>       * this class.
>       *
>       * @return          default graphics configuration
>       */
>      public static GraphicsConfiguration getDefaultConfiguration() {
>          return GraphicsEnvironment.getLocalGraphicsEnvironment().
>           getDefaultScreenDevice().getDefaultConfiguration();
>      }
> }
> 
> 
> 
> -- 
> 
> Knute Johnson

I've never used an AffineTransformOp.
To change the size of an image I just generate a new image of the width/height/transparency I want.  Then I get the Graphics of the new image, cast it to a Graphics2D, create a new AffineTransform, and set the translate/scale/rotate I want.  Then I call .setComposite(AlphaComposite.SrcOver) on the new image's Graphics2D, then just .drawImage() passing in the old image, the AffineTransform I just created, and the observer (normally null).

Normally you want to maintain proportions, your x and y for the scale are both Math.min(newWidth / originalImageWidth, newHeight / originalImageHeight).

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Thread

Can you resize with BufferedImage Cecil Westerhof <Cecil@decebal.nl> - 2017-04-12 10:34 +0200
  Re: Can you resize with BufferedImage Martin Gregorie <martin@address-in-sig.invalid> - 2017-04-12 10:18 +0000
    Re: Can you resize with BufferedImage Cecil Westerhof <Cecil@decebal.nl> - 2017-04-12 14:08 +0200
      Re: Can you resize with BufferedImage Martin Gregorie <martin@address-in-sig.invalid> - 2017-04-12 13:06 +0000
        Re: Can you resize with BufferedImage Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2017-04-12 10:05 -0500
          Re: Can you resize with BufferedImage Eric Douglas <e.d.programmer@gmail.com> - 2017-04-12 08:20 -0700
            Re: Can you resize with BufferedImage Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2017-04-13 11:10 -0500
          Re: Can you resize with BufferedImage Martin Gregorie <martin@address-in-sig.invalid> - 2017-04-12 16:13 +0000

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