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Java: dynamically create a png image from BufferedImage

I want to dynamically create an image, and the created image must meet some requirements.
The created image should be a png, and it must have the same behavior as if it's a loaded png from a file.
It's for creating a texture to use in LWJGL.
When I load a png image as a file and have a BufferedImage, I can use the following code for my texture:
(The Texture constructor is designed for using with loaded images)
public class Texture {
public Texture(BufferedImage bi) {
width = bi.getWidth();
height = bi.getHeight();
System.out.println(bi.toString());
int[] pixels_raw = new int[width * height];
pixels_raw = bi.getRGB(0, 0, width, height, null, 0, width);
ByteBuffer pixels = BufferUtils.createByteBuffer(width * height * 4);
for(int i = 0; i < width; i++) {
for(int j = 0; j < height; j++) {
int pixel = pixels_raw[i * width + j]; // This is the error line.
pixels.put((byte)((pixel >> 16) & 0xFF)); // red
pixels.put((byte)((pixel >> 8) & 0xFF)); // green
pixels.put((byte)(pixel & 0xFF)); // blue
pixels.put((byte)((pixel >> 24) & 0xFF)); // alpha
}
}
pixels.flip();
id = glGenTextures();
glBindTexture(GL_TEXTURE_2D, id);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
}
}
But when I try to create an image dynamically, without loading anything from a file, then I get an ArrayIndexOutOfBoundsException on line 18 of the above code (see comment in code).
Of course it has something to do with the bits per pixel of the created BufferedImage. I tried changing the image type for my BufferedImage, and changing the array size when initializing the pixels_raw array. But I still get array exceptions. So, the above constructor method does only works when I pass a BufferedImage instance which comes from a loaded png. When I pass in a BurfferedImage I created dynamically with the code below, it gives me the exceptions I mentioned before.
public class TextDrawer {
public BufferedImage drawText(String text, Font font, Color color) {
BufferedImage graphicsGetterBi = new BufferedImage(1, 1, BufferedImage.TYPE_INT_ARGB);
Graphics g = graphicsGetterBi.getGraphics();
Graphics2D g2 = (Graphics2D) g;
Rectangle2D bounds = font.getStringBounds(text, 0, text.length(), g2.getFontRenderContext());
BufferedImage bi = new BufferedImage((int) bounds.getWidth(), (int) bounds.getHeight(), BufferedImage.TYPE_INT_ARGB);
System.out.println("Created the image. \n");
g2.setColor(color);
g2.setFont(font);
g2.drawString(text, 0, 0);
return bi;
}
}

instead of int pixel = pixels_raw[i * width + j]; it should be int pixel = pixels_raw[i * height + j]; or int pixel = pixels_raw[j * width + i];. Consider you have image of width = 2x and height = x. Then the array size is 2x^2, while the maximum index you request for is (2x - 1) * 2x + x - 1 = 4x^2 - x - 1, which is more than 2x^2 for x > 2

Best way to create Image from palette Color array + indice byte array?

I'm developing a Java component for displaying some videos and for each frame of the video, my decoder gives me a Color[256] palette + a width*height bytes pixel indices array. Here's how I create my BufferedImage right now:
byte[] iArray = new byte[width * height * 3];
int j = 0;
for (byte i : this.lastFrameData) {
iArray[j] = (byte) this.currentPalette[i & 0xFF].getRed();
iArray[j + 1] = (byte) this.currentPalette[i & 0xFF].getGreen();
iArray[j + 2] = (byte) this.currentPalette[i & 0xFF].getBlue();
j += 3;
}
DataBufferByte dbb = new DataBufferByte(iArray, iArray.length);
ColorModel cm = new ComponentColorModel(ColorSpace.getInstance(ColorSpace.CS_sRGB), new int[] { 8, 8, 8 }, false, false, Transparency.OPAQUE, DataBuffer.TYPE_BYTE);
return new BufferedImage(cm, Raster.createInterleavedRaster(dbb, width, height, width * 3, 3, new int[] { 0, 1, 2 }, null), false, null);
This works but it looks ugly and I'm sure there is a better way. So what would the fastest way to create the BufferedImage be then?
/Edit: I've tried using the setRGB method directly on my BufferedImage but it resulted in worse performance than the above.
Thanks

I would do this:
int[] imagePixels = new int[width * height]
int j = 0;
for (byte i : this.lastFrameData) {
byte r = (byte) this.currentPalette[i & 0xFF].getRed();
byte g = (byte) this.currentPalette[i & 0xFF].getGreen();
byte b = (byte) this.currentPalette[i & 0xFF].getBlue();
imagePixels[j] = 0xFF000000 | (r<<16) | (g<<8) | b;
j++;
}
BufferedImage result = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
result.setRGB(0, 0, width, height, imagePixels , 0, width);
return result;
Maybe it is faster don't test it yet.

How to set RGB pixel in a BufferedImage to display a 16-bit-depth PNG?

I am trying to read and show a PNG file.
I have no problem dealing with images with 8-bit depth.
I proceed as follow:
BufferedImage result = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Then I read the 3*8=24 bits of each pixel, save them in an array of byte data and put them in the image with:
for (int y = 0; y < height; y++)
for (int x = 0; x < width; x++)
result.setRGB(x, y, ((data[x * 3 + 0] & 0xff) << 16)
+ ((data[x * 3 + 1] & 0xff) << 8)
+ ((data[x * 3 + 2] & 0xff)));
The problem is now with 16-bit depth images. Of course data is bigger now and it contains 48bits, divided in 6 bytes, for each RGB triple: from the debugger data has the values I expect.
How can I set the RGB pixel? Do I have to change the BufferedImage declaration? Maybe with:
BufferedImage result = new BufferedImage(width, height, BufferedImage.TYPE_USHORT_565_RGB);
Many thanks in advance!
P.S.: following PNG standars, the image has color type 2 (RGB without alpha).
Maybe I'll have to use http://docs.oracle.com/javase/7/docs/api/java/awt/image/ColorModel.html

#haraldK has pointed in the right direction. I'm providing some working code which is from "PNGReader" of "icafe" Java image library.
if(bitsPerPixel == 16) {
if(interlace_method==NON_INTERLACED)
spixels = generate16BitRGBPixels(compr_data, false);
else {
spixels = generate16BitRGBInterlacedPixels(compr_data, false);
}
int[] off = {0, 1, 2}; //band offset, we have 3 bands
int numOfBands = 3;
boolean hasAlpha = false;
int trans = Transparency.OPAQUE;
int[] nBits = {16, 16, 16};
if(alpha != null) { // Deal with single color transparency
off = new int[] {0, 1, 2, 3}; //band offset, we have 4 bands
numOfBands = 4;
hasAlpha = true;
trans = Transparency.TRANSLUCENT;
nBits = new int[] {16, 16, 16, 16};
}
db = new DataBufferUShort(spixels, spixels.length);
raster = Raster.createInterleavedRaster(db, width, height, width*numOfBands, numOfBands, off, null);
cm = new ComponentColorModel(colorSpace, nBits, hasAlpha, false, trans, DataBuffer.TYPE_USHORT);
}
return new BufferedImage(cm, raster, false, null);
Here is the generate16BitRGBPixels() method:
private short[] generate16BitRGBPixels(byte[] compr_data, boolean fullAlpha) throws Exception {
//
int bytesPerPixel = 0;
byte[] pixBytes;
if (fullAlpha)
bytesPerPixel = 8;
else
bytesPerPixel = 6;
bytesPerScanLine = width*bytesPerPixel;
// Now inflate the data.
pixBytes = new byte[height * bytesPerScanLine];
// Wrap an InflaterInputStream with a bufferedInputStream to speed up reading
BufferedInputStream bis = new BufferedInputStream(new InflaterInputStream(new ByteArrayInputStream(compr_data)));
apply_defilter(bis, pixBytes, height, bytesPerPixel, bytesPerScanLine);
short[] spixels = null;
if(alpha != null) { // Deal with single color transparency
spixels = new short[width*height*4];
short redMask = (short)((alpha[1]&0xff)|(alpha[0]&0xff)<<8);
short greenMask = (short)((alpha[3]&0xff)|(alpha[2]&0xff)<<8);;
short blueMask = (short)((alpha[5]&0xff)|(alpha[4]&0xff)<<8);
for(int i = 0, index = 0; i < pixBytes.length; index += 4) {
short red = (short)((pixBytes[i++]&0xff)<<8|(pixBytes[i++]&0xff));
short green = (short)((pixBytes[i++]&0xff)<<8|(pixBytes[i++]&0xff));
short blue = (short)((pixBytes[i++]&0xff)<<8|(pixBytes[i++]&0xff));
spixels[index] = red;
spixels[index + 1] = green;
spixels[index + 2] = blue;
if(spixels[index] == redMask && spixels[index + 1] == greenMask && spixels[index + 2] == blueMask) {
spixels[index + 3] = (short)0x0000;
} else {
spixels[index + 3] = (short)0xffff;
}
}
} else
spixels = ArrayUtils.toShortArray(pixBytes, true);
return spixels;
}
and the ArrayUtils.toShortArray() method:
public static short[] toShortArray(byte[] data, int offset, int len, boolean bigEndian) {
ByteBuffer byteBuffer = ByteBuffer.wrap(data, offset, len);
if (bigEndian) {
byteBuffer.order(ByteOrder.BIG_ENDIAN);
} else {
byteBuffer.order(ByteOrder.LITTLE_ENDIAN);
}
ShortBuffer shortBuf = byteBuffer.asShortBuffer();
short[] array = new short[shortBuf.remaining()];
shortBuf.get(array);
return array;
}

If you want to create an image with 16 bits per sample (or 48 bits per pixel), there is no BufferedImage.TYPE_... constant for that. TYPE_USHORT_565_RGB creates an image with 16 bits per pixel, with samples of 5 (red), 6 (green) and 5 (blue) bits respectively. I think these USHORT RGB values are leftovers from a time when some computes actually had the option of a 16 bit display (aka "Thousands of colors").
What you need to do, to actually create an image with 16 bits per sample, is:
ColorModel cm;
WritableRaster raster;
BufferedImage result = new BufferedImage(cm, raster, cm.isAlphaPremultiplied(), null);
The raster is created from a data buffer of type DataBufferUShort with either 3 banks and a BandedSampleModel with 3 bands, or use a single bank and a PixelInterleavedSampleModel with a pixelStride of 3, scanLineStride of 3 * width and bandOffsets {0, 1, 2}.
Here's a full sample, using interleaved sample model:
ColorSpace sRGB = ColorSpace.getInstance(ColorSpace.CS_sRGB)
ColorModel cm = new ComponentColorModel(sRGB, false, false, Transparency.OPAQUE, DataBuffer.TYPE_USHORT);
WritableRaster raster = Raster.createInterleavedRaster(DataBuffer.TYPE_USHORT, w, h, 3, null);
BufferedImage rgb = new BufferedImage(cm, raster, cm.isAlphaPremultiplied(), null);
PS: With the data buffer exposed, you can access the short samples directly, to manipulate the pixels. This is much faster than using BufferedImage.getRGB(...)/setRGB(...), and will keep the original 16 bit per sample precision. BufferedImage.getRGB(...) will convert the pixel values to 32 bit pixel/8 bit per sample, and thus lose the extra precision.

Java byte Image Manipulation

I need to create a simple demo for image manipulation in Java. My code is swing based. I don't have to do anything complex, just show that the image has changed in some way. I have the image read as byte[]. Is there anyway that I can manipulate this byte array without corrupting the bytes to show some very simple manipulation. I don't wish to use paint() etc. Is there anything that I can do directly to the byte[] array to show some change?
edit:
I am reading jpg image as byteArrayInputStream using apache io library. The bytes are read ok and I can confirm it by writing them back as jpeg.

You can try to convert your RGB image to Grayscale. If the image as 3 bytes per pixel rapresented as RedGreenBlue you can use the followinf formula: y=0.299*r+0.587*g+0.114*b.
To be clear iterate over the byte array and replace the colors. Here an example:
byte[] newImage = new byte[rgbImage.length];
for (int i = 0; i < rgbImage.length; i += 3) {
newImage[i] = (byte) (rgbImage[i] * 0.299 + rgbImage[i + 1] * 0.587
+ rgbImage[i + 2] * 0.114);
newImage[i+1] = newImage[i];
newImage[i+2] = newImage[i];
}
UPDATE:
Above code assumes you're using raw RGB image, if you need to process a Jpeg file you can do this:
try {
BufferedImage inputImage = ImageIO.read(new File("input.jpg"));
BufferedImage outputImage = new BufferedImage(
inputImage.getWidth(), inputImage.getHeight(),
BufferedImage.TYPE_INT_RGB);
for (int x = 0; x < inputImage.getWidth(); x++) {
for (int y = 0; y < inputImage.getHeight(); y++) {
int rgb = inputImage.getRGB(x, y);
int blue = 0x0000ff & rgb;
int green = 0x0000ff & (rgb >> 8);
int red = 0x0000ff & (rgb >> 16);
int lum = (int) (red * 0.299 + green * 0.587 + blue * 0.114);
outputImage
.setRGB(x, y, lum | (lum << 8) | (lum << 16));
}
}
ImageIO.write(outputImage, "jpg", new File("output.jpg"));
} catch (IOException e) {
e.printStackTrace();
}

Does .Net PixelFormat have Java equivalent?

What in Java matches to C# PixelFormat's members.
i.e. Format24bppRgb matches to BufferedImage.TYPE_INT_RGB?
Here is my code. I got an image which has .Net's PixelFormat = Format32bppArgb. I am creating BufferedImage like this:
int sizeBytes = width * height;
DataBufferByte dataBuffer = new DataBufferByte(myImageBytes, sizeBytes);
WritableRaster raster = Raster.createInterleavedRaster(dataBuffer, // dataBuffer
width, // width
height, // height
width * 4, // scanlineStride
4, // pixelStride
new int[]{0, 1, 2, 3}, // bandOffsets
null); // location
java.awt.image.ColorModel colorModel = new ComponentColorModel(ColorSpace.getInstance(ColorSpace.CS_sRGB), // ColorSpace
new int[]{8, 8, 8, 8}, // bits
true, // hasAlpha
false, // isPreMultiplied
ComponentColorModel.TRANSLUCENT, DataBuffer.TYPE_BYTE);
BufferedImage result = new BufferedImage(colorModel, raster, false, null);
After I create a bufferedImage red and blue colors are swapped in it.
Next, I tried to create an image as follow
BufferedImage result = new BufferedImage(width, height, BufferedImage.TYPE_4BYTE_ABGR);
WritableRaster r = result.getRaster();
int[] pixels = byteToInt(bytes);
r.setPixels(0, 0, width, height , pixels); // ! Here an exception occures, because after I converted the byte array to int one the width becomes too long.
Byte array was convert by this method
private int[] byteToInt(byte[] pixels) {
int[] ints = new int[pixels.length / 3];
int byteIdx = 0;
for (int pixel = 0; pixel < ints.length; pixel++) {
int red = (int) pixels[byteIdx++] & 0xFF;
int green = (int) pixels[byteIdx++] & 0xFF;
int blue = (int) pixels[byteIdx++] & 0xFF;
int rgb = (red << 16) | (green << 8) | blue;
ints[pixel] = rgb;
}
return ints;
}
The colors look fine now, but I got the exception
java.lang.ArrayIndexOutOfBoundsException: 27600
at sun.awt.image.ByteInterleavedRaster.setPixels(ByteInterleavedRaster.java:1106)
If I use the smaller width (e.g. width / 3) the colors look fine but the picture itself shrinks.

BufferedImage is definately a good place to start. Many of the values in PixelFormat will match up to values in BufferedImage - they each have 24-bit and 32-bit RGB/ARGB values, both have 5-5-5 and 5-6-5 combinations, etc.
If you're having trouble, post some code and we'll have a look at it, try to help. The thing I would recommend would be to play around with the byte ordering (in the pixel ints) until you get the result that you expect - try drawing the BufferedImage onto a GUI object like JPanel so you can see what it looks like.
If you've got an array of int[] for your pixel values, this is the code I usually use for displaying the array as an image...
int[] pixels;
ColorModel model = new DirectColorModel(32,0x00ff0000,0x0000ff00,0x000000ff,0xff000000);
Image image = new JLabel().createImage(new MemoryImageSource(width,height,model,pixels,0,width));