Develop Reference

How draw images with hardware acceleration on all platforms?

I've created 256x256 image with red=x and alpha=y:
int[] pix = new int[256*256];
for (int i = 0; i < pix.length; ++i)
pix[i] = i << 16;
BufferedImage img1 = new BufferedImage(256, 256, BufferedImage.TYPE_INT_ARGB);
img1.setRGB(0, 0, 256, 256, pix, 0, 256);
and have copied to volatile image:
VolatileImage img2 = canvas.createVolatileImage(256, 256);
img2.createGraphics().drawImage(img1, 0, 0, null);
When i draw BufferedImage to canvas, it incorrectly process alpha and not accelerated (0.9msec for drawImage):
When i draw VolatileImage, it process alpha and accelerated (0.03ms):
But it under Windows. Under MacOS i see different result. For BufferedImage it do not process alpha, but accelerated, for VolatileImage it process alpha correctly, but NOT accelerated. (Or maybe both not accelerated, just software processing of BufferedImage much faster).
Question - how correctly draw image with correct alpha processing and with acceleration on all platforms.
ps. img2.setAccelerationPriority(1) has no any effect.
pps. i was wrong, it not correct alpha processing in second case, it just precalculated image with alpha applied to default background color of cavas.

System.getProperties().setProperty("sun.java2d.opengl", "true");
This setting resolved problem with acceleration, now there 0.004msec for drawImage
And there was no problem with alpha processing at all, i just draw same image with alpha 1000 times at same place for time testing and it caused such ugly picture

JavaFX: Fastest way to write pixels to PixelWriter

I'm looking for the fastest way to write pixels on javafx.scene.image.Image. Writing to BufferedImage's backing array is much faster. At least on the test image I made it took only ~20ms for BufferedImage, WritableImage on the other hand took ~100ms. I already tried SwingFXUtils but no luck.
Code for BufferedImage (faster):
BufferedImage bi = createCompatibleImage( width, height );
WritableRaster raster = bi.getRaster();
DataBufferInt dataBuffer = (DataBufferInt) raster.getDataBuffer();
System.arraycopy( pixels, 0, dataBuffer.getData(), 0, pixels.length );
Code for WritableImage (slower):
WritableImage wi = new WritableImage( width, height );
PixelWriter pw = wi.getPixelWriter();
WritablePixelFormat<IntBuffer> pf = WritablePixelFormat.getIntArgbInstance();
pw.setPixels( 0, 0, width, height, pf, pixels, 0, width );
Maybe there's a way to write to WritableImage's backing array too?

For the performance of the pixel writer it is absolutely crucial that you pick the right pixel format. You can check what the native pixel format is via
pw.getPixelFormat().getType()
On my Mac this is PixelFormat.Type.BYTE_BGRA_PRE. If your raw data conforms to this pixel format, then the transfer to the image should be pretty fast. Otherwise the pixel data has to be converted and that takes some time.

Reduce the size of an image in java

I want to make sure that an image in my application is not more than 200x200 px and the image size is not more than 150 kB. For example, if the file size of image is more than 150 kB i need to make it 150 kB. The image can be of type jpeg,png etc.
I have the following code for resizing an image to a given width and height
private BufferedImage resize(BufferedImage img, int newW, int newH) {
int w = img.getWidth();
int h = img.getHeight();
BufferedImage dimg = new BufferedImage(newW, newH, img.getType());
Graphics2D g = dimg.createGraphics();
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(img, 0, 0, newW, newH, 0, 0, w, h, null);
g.dispose();
return dimg;
}
But im not sure how to go about reducing the file size to 150 kB. How to do that in java ?.Some example would be really appreciated.
Thank You

Just as an option - image magic - it also has some convenience wrappers for Java, so you can easily use it.

Does your question have any practical relevance or is it just theoretical?
A 200x200 pixel image with a colour depth of 24 bit will uncompressed require 117kB. If you use any reasonable JPEG encoder, it will also never exceed 150kB for such an image.

You can only rezise the image multiple times, to get below the determined file size.

Can I save a huge PNG without the whole thing being in memory?

I'm saving a very large PNG (25 MB or so) with Java. The problem is that while it's being generated, it's using 3+ gigabytes of memory, which is not ideal since it severely slows down systems with low memory.
The code I'm working with needs to combine a set of tiled images into a single image; in other words, I have nine images (PNG):
A1 A2 A3
B1 B2 B3
C1 C2 C3
which need to be combined into a single image.
The code I'm using is this:
image = new BufferedImage(width, height, height, BufferedImage.TYPE_INT_ARGB_PRE);
g2d = image.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
// draw the 9 images on here at their proper positions...
// save image
g2d.dispose();
File file = getOutputFile();
ImageIO.write(image, "png", file);
Is there a way to make and save an image without having the entire image in memory?
Edit:
To draw the images, I'm doing this in a loop:
BufferedImage tile = ImageIO.read(new File("file.png"));
g2d.drawImage(tile, x, y, w, h);
This is being repeated many times (it's usually about 25x25, but sometimes more), so if there is even a small memory leak here, that could be causing the problem.

You can also take a look at this PNGJ library (disclaimer: I coded it), it allows to save a PNG image line by line.

ImageIO.write(image, "png", file); is internally using com.sun.imageio.plugins.png.PNGImageWriter. That method and that writer expect image to be a rendered image but PNG writting is done by 'bands' so you can make a subclass of RenderedImage that generates the requested bands of the composed large image as the writer ask for that bands to the image.
From PNGImageWriter class:
private void encodePass(ImageOutputStream os,
RenderedImage image,
int xOffset, int yOffset,
int xSkip, int ySkip) throws IOException {
// (...)
for (int row = minY + yOffset; row < minY + height; row += ySkip) {
Rectangle rect = new Rectangle(minX, row, width, 1); // <--- *1
Raster ras = image.getData(rect); // <--- *2
*2 I think this is the only place where the writer reads pixels from you image. You should make a getData(rect) method that computes that rect joining 3 bands from 3 images into one.
*1 As you see it reads bands with a height of 1 pixel.
If the things are as I think you should only need to compose 3 images at a time. There would be no need for the other 6 to be in memory.
I know it is not an easy solution but it might help you if you don't find anything easier.

Would using an external tool be an option? I remember using ImageMagick for similar purpose, you would need to save your smaller images first.

Why does this GIF end up as a black square when resizing with Java ImageIO

Java ImageIO correctly displays this black & white image http://www.jthink.net/jaikoz/scratch/black.gif but when I try and resize it using this code
public static BufferedImage resize2D(Image srcImage, int size)
{
int w = srcImage.getWidth(null);
int h = srcImage.getHeight(null);
// Determine the scaling required to get desired result.
float scaleW = (float) size / (float) w;
float scaleH = (float) size / (float) h;
MainWindow.logger.finest("Image Resizing to size:" + size + " w:" + w + ":h:" + h + ":scaleW:" + scaleW + ":scaleH" + scaleH);
//Create an image buffer in which to paint on, create as an opaque Rgb type image, it doesn't matter what type
//the original image is we want to convert to the best type for displaying on screen regardless
BufferedImage bi = new BufferedImage(size, size, BufferedImage.TYPE_INT_RGB);
// Set the scale.
AffineTransform tx = new AffineTransform();
tx.scale(scaleW, scaleH);
// Paint image.
Graphics2D g2d = bi.createGraphics();
g2d.setComposite(AlphaComposite.Src);
g2d.drawImage(srcImage, tx, null);
g2d.dispose();
return bi;
}
I just end up with a black image. Im trying to make the image smaller (a thumbnail) but even if I resize it larger for test purposes it still ends up as a black square.
Other images resize okay, anyone know what is the problem with the gif/and or Java Bug

Here is the string representation of the ColorModel of the linked image when loaded through ImageIO:
IndexColorModel: #pixelBits = 1 numComponents = 4 color space = java.awt.color.ICC_ColorSpace#1572e449 transparency = 2 transIndex = 1 has alpha = true isAlphaPre = false
If I understand this correctly, you have one bit per pixel, where a 0 bit is opaque black and a 1 bit is transparent. Your BufferedImage is initially all black, so drawing a mixture of black and transparent pixels onto it will have no effect.
Although you are using AlphaComposite.Src this will not help as the R/G/B values for the transparent palette entry read as zero (I am not sure whether this is encoded in the GIF or just the default in the JDK.)
You can work around it by:
Initializing the BufferedImage with all-white pixels
Using AlphaComposite.SrcOver
So the last part of your resize2D implementation would become:
// Paint image.
Graphics2D g2d = bi.createGraphics();
g2d.setColor(Color.WHITE);
g2d.fillRect(0, 0, size, size);
g2d.setComposite(AlphaComposite.SrcOver);
g2d.drawImage(srcImage, tx, null);

Try this:
BufferedImage bi = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
That makes it work. Of course, the question is why..?