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Convert color image into black and white using java created from scratch

I want to convert my picture from colored to Black and white which seems to be created from scratch.
Here is the code which i tried as described on the different post:
BufferedImage bi = ImageIO.read(new File("/Users/***/Documents/Photograph.jpg"));
ColorConvertOp op =
new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null);
ImageIO.write(bi, "PNG", new File("/Users/bng/Documents/rendered2.png"));
op.filter(bi, bi);
But still my image is not converted to the Black and white. Additionally, this code is increasing the rendered2.png image size to 10 folds.
Also, it would be great if i could find some Java 8 way of doing this.
Any suggestions?

Here is the code which worked for me:
BufferedImage input = ImageIO.read(new File("/Users/bng/Documents/Photograph.jpg"));
// Create a black-and-white image of the same size.
BufferedImage im = new BufferedImage(input.getWidth(), input.getHeight(), BufferedImage.TYPE_BYTE_BINARY);
// Get the graphics context for the black-and-white image.
Graphics2D g2d = im.createGraphics();
// Render the input image on it.
g2d.drawImage(input, 0, 0, null);
// Store the resulting image using the PNG format.
ImageIO.write(im, "PNG", new File("/Users/bng/Documents/rendered.png"));
It was BufferedImage.TYPE_BYTE_BINARY which provided me the exact solution.
Lokking for the Java 8 Version for above code.

You have to find RGB of the existing colors of the image you want to change it.
Fyi, you want to change it as white RGB value is (255,255,255) and for black RGB value is (0,0,0)
Following method easily do the color change if you apply correct way of your requirement
private BufferedImage changeColor(BufferedImage image, int srcColor, int replaceColor)
{
BufferedImage destImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g = destImage.createGraphics();
g.drawImage(image, null, 0, 0);
g.dispose();
for (int width = 0; width < image.getWidth(); width++)
{
for (int height = 0; height < image.getHeight(); height++)
{
if (destImage.getRGB(width, height) == srcColor)
{
destImage.setRGB(width, height, replaceColor);
}
}
}
return destImage;
}

you have to use the ColorConvertOp in a proper way:
create Source image
apply filter
save dest
example:
BufferedImage src = ImageIO.read(new File("/Users/***/Documents/Photograph.jpg"));
ColorConvertOp op =
new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null);
BufferedImage dest = op.filter(src, null);
ImageIO.write(dest, "PNG", new File("/Users/bng/Documents/rendered2.png"));
src:
dest:

Stripping Alpha Channel from Images

I want to strip the alpha channel (transparent background) from PNGs, and then write them as JPEG images. More correctly, I'd like to make the transparent pixels white. I've tried two techniques, both of which fail in different ways:
Approach 1:
BufferedImage rgbCopy = new BufferedImage(inputImage.getWidth(), inputImage.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D graphics = rgbCopy.createGraphics();
graphics.drawImage(inputImage, 0, 0, Color.WHITE, null);
graphics.dispose();
return rgbCopy;
Result: image has a pink background.
Approach 2:
final WritableRaster raster = inputImage.getRaster();
final WritableRaster newRaster = raster.createWritableChild(0, 0, inputImage.getWidth(), inputImage.getHeight(), 0, 0, new int[]{0, 1, 2});
ColorModel newCM = new ComponentColorModel(inputImage.getColorModel().getColorSpace(), false, false, Transparency.OPAQUE, DataBuffer.TYPE_BYTE);
return new BufferedImage(newCM, newRaster, false, null);
Result: Image has a black background.
In both cases, the input image is a PNG and the output image is written as a JPEG as follows: ImageIO.write(bufferedImage, "jpg", buffer). In case it's relevant: this is on Java 8 and I'm using the twelvemonkeys library to resize the image before writing it as a JPEG.
I've experimented with a number of variations of the above code, with no luck. There are a number of previous questions that suggest the above code, but it doesn't seem to be working in this case.

Thanks to Rob's answer, we now know why the colors are messed up.
The problem is twofold:
The default JPEGImageWriter that ImageIO uses to write JPEG, does not write JPEGs with alpha in a way other software understands (this is a known issue).
When passing null as the destination to ResampleOp.filter(src, dest) and the filter method is FILTER_TRIANGLE, a new BufferedImage will be created, with alpha (actually, BufferedImage.TYPE_INT_ARGB).
Stripping out the alpha after resampling will work. However, there is another approach that is likely to be faster and save some memory. That is, instead of passing a null destination, pass a BufferedImage of the appropriate size and type:
public static void main(String[] args) throws IOException {
// Read input
File input = new File(args[0]);
BufferedImage inputImage = ImageIO.read(input);
// Make any transparent parts white
if (inputImage.getTransparency() == Transparency.TRANSLUCENT) {
// NOTE: For BITMASK images, the color model is likely IndexColorModel,
// and this model will contain the "real" color of the transparent parts
// which is likely a better fit than unconditionally setting it to white.
// Fill background with white
Graphics2D graphics = inputImage.createGraphics();
try {
graphics.setComposite(AlphaComposite.DstOver); // Set composite rules to paint "behind"
graphics.setPaint(Color.WHITE);
graphics.fillRect(0, 0, inputImage.getWidth(), inputImage.getHeight());
}
finally {
graphics.dispose();
}
}
// Resample to fixed size
int width = 100;
int height = 100;
BufferedImageOp resampler = new ResampleOp(width, height, ResampleOp.FILTER_TRIANGLE);
// Using explicit destination, resizedImg will be of TYPE_INT_RGB
BufferedImage resizedImg = resampler.filter(inputImage, new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB));
// Write output as JPEG
ImageIO.write(resizedImg, "JPEG", new File(input.getParent(), input.getName().replace('.', '_') + ".jpg"));
}

haraldk was correct, there was another piece of code that was causing the alpha channel issue. The code in approach 1 is correct and works.
However if, after stripping the alpha channel, you resize the image using twelvemonkeys ResampleOp as follows:
BufferedImageOp resampler = new ResampleOp(width, height, ResampleOp.FILTER_TRIANGLE);
BufferedImage resizedImg = resampler.filter(rgbImage, null);
This causes the alpha channel to be pink.
The solution is to resize the image before stripping the alpha channel.

How to convert a Type_Byte_Binary BufferedImage with Alpha to an TYPE_4BYTE_ABGR

Im using the code
BufferedImage imgIn = ImageIO.read(is);
BufferedImage image;
if (imgIn.getType() != BufferedImage.TYPE_BYTE_INDEXED) {
image = new BufferedImage(imgIn.getWidth(), imgIn.getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
ColorConvertOp cco = new ColorConvertOp(imgIn.getColorModel()
.getColorSpace(), image.getColorModel().getColorSpace(), null);
cco.filter(imgIn, image);
} else {
image = imgIn;
}
When I'm pulling in an image with a Bit Depth of 4 it makes the imgIn a Type_Byte_Binary. When It gets converted to Type_4Byte_ABGR anything with partial transparency changes color and loses all alpha. Fully transparent pixels and Fully Opaque pixels remained unchanged.
Is there anything I can do to keep the partially transparent pixels from changing?
Thanks.

Most likely ColorConvertOp isn't what you are after here, because the images are all in RGB (sRGB) color space (IndexColorModel doesn't support other color spaces).
Instead, just paint your TYPE_BYTE_INDEXED or TYPE_BYTE_BINARY onto a TYPE_4BYTE_ABGR image, and any transparency should be preserved.
BufferedImage image = new BufferedImage(imgIn.getWidth(), imgIn.getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
Grphics2D g = image.createGraphics();
try {
g.drawImage(imgIn, 0, 0, null);
}
finally {
g.dispose();
}

BufferedImage red mask

I have to take screenshot of some area on the desktop.
I am doing it this way:
BufferedImage image = new Robot().createScreenCapture(area.areaRect);
ImageIO.write(image, "jpg", new File(current));
//then I paint in on JPanel
and every screenshot saved to .jpg looks like this one:
It doesn't happen for pngs and gifs.
I googled about this problem and found a solution, creating image by the Toolkit class:
Image toolkitImage = Toolkit.getDefaultToolkit().createImage(imageUrl);
but I have no idea how can I take screenshot with it.

The JPEG writer in ImageIO doesn't take the ColorModel into account when writing the file, as JPEG does not have an alpha channel. The Alpha channel is the A part of ARGB that specifies the transparency value for each pixel. Most image clients will assume that JPEG don't have alpha values as that is the standard behavior.
The writer in ImageIO will write a file with the colors shifted, like the lovely shade of salmon as background in the picture. This is because the writer will write down the values wrong when it really should be writing them in RBG.
The workaround is to paint the image to a BufferedImage with RBG as ColorModel. Here is some sample code:
// argbBuffer is the ARGB Image that should be written as JPEG:
WritableRaster raster = argbBuffer.getRaster();
WritableRaster newRaster = raster.createWritableChild(0, 0, width, height, 0, 0, new int[] {0, 1, 2});
// create a ColorModel that represents the one of the ARGB except the alpha channel:
DirectColorModel cm = (DirectColorModel)argbBuffer.getColorModel();
DirectColorModel newCM = new DirectColorModel(cm.getPixelSize(),
cm.getRedMask(), cm.getGreenMask(), cm.getBlueMask());
// now create the new buffer that is used ot write the image:
BufferedImage rgbBuffer = new BufferedImage(newCM, newRaster, false, null);

Converting transparent gif / png to jpeg using java

I'd like to convert gif images to jpeg using Java. It works great for most images, but I have a simple transparent gif image:
Input gif image http://img292.imageshack.us/img292/2103/indexedtestal7.gif
[In case the image is missing: it's a blue circle with transparent pixels around it]
When I convert this image using the following code:
File file = new File("indexed_test.gif");
BufferedImage image = ImageIO.read(file);
File f = new File("indexed_test.jpg");
ImageIO.write(image, "jpg", f);
This code works without throwing an Exception, but results an invalid jpeg image:
[In case the image is missing: IE cannot show the jpeg, Firefox shows the image with invalid colors.]
I'm using Java 1.5.
I also tried converting the sample gif to png with gimp and using the png as an input for the Java code. The result is the same.
Is it a bug in the JDK? How can I convert images correctly preferably without 3rd party libraries?
UPDATE:
Answers indicate that jpeg conversion cannot handle transparency correctly (I still think that this is a bug) and suggest a workaround for replacing transparent pixels with predefined color. Both of the suggested methods are quite complex, so I've implemented a simpler one (will post as an answer). I accept the first published answer with this workaround (by Markus). I don't know which implementation is the better. I go for the simplest one still I found a gif where it's not working.

For Java 6 (and 5 too, I think):
BufferedImage bufferedImage = new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_RGB);
g = bufferedImage.createGraphics();
//Color.WHITE estes the background to white. You can use any other color
g.drawImage(image, 0, 0, bufferedImage.getWidth(), bufferedImage.getHeight(), Color.WHITE, null);

As already mentioned in the UPDATE of the question I've implemented a simpler way of replacing transparent pixels with predefined color:
public static BufferedImage fillTransparentPixels( BufferedImage image,
Color fillColor ) {
int w = image.getWidth();
int h = image.getHeight();
BufferedImage image2 = new BufferedImage(w, h,
BufferedImage.TYPE_INT_RGB);
Graphics2D g = image2.createGraphics();
g.setColor(fillColor);
g.fillRect(0,0,w,h);
g.drawRenderedImage(image, null);
g.dispose();
return image2;
}
and I call this method before jpeg conversion in this way:
if( inputImage.getColorModel().getTransparency() != Transparency.OPAQUE) {
inputImage = fillTransparentPixels(inputImage, Color.WHITE);
}

The problem (at least with png to jpg conversion) is that the color scheme isn't the same, because jpg doesn't support transparency.
What we've done successfully is something along these lines (this is pulled from various bits of code - so please forgive the crudeness of the formatting):
File file = new File("indexed_test.gif");
BufferedImage image = ImageIO.read(file);
int width = image.getWidth();
int height = image.getHeight();
BufferedImage jpgImage;
//you can probably do this without the headless check if you just use the first block
if (GraphicsEnvironment.isHeadless()) {
if (image.getType() == BufferedImage.TYPE_CUSTOM) {
//coerce it to TYPE_INT_ARGB and cross fingers -- PNGs give a TYPE_CUSTOM and that doesn't work with
//trying to create a new BufferedImage
jpgImage = new BufferedImage(width,height,BufferedImage.TYPE_INT_ARGB);
} else {
jpgImage = new BufferedImage(width, height, image.getType());
}
} else {
jgpImage = GraphicsEnvironment.getLocalGraphicsEnvironment().
getDefaultScreenDevice().getDefaultConfiguration().
createCompatibleImage(width, height, image.getTransparency());
}
//copy the original to the new image
Graphics2D g2 = null;
try {
g2 = jpg.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
g2.drawImage(image, 0, 0, width, height, null);
}
finally {
if (g2 != null) {
g2.dispose();
}
}
File f = new File("indexed_test.jpg");
ImageIO.write(jpgImage, "jpg", f);
This works for png to jpg and gif to jpg. And you will have a white background where the transparent bits were. You can change this by having g2 fill the image with another color before the drawImage call.

3 months late, but I am having a very similar problem (although not even loading a gif, but simply generating a transparent image - say, no background, a colored shape - where when saving to jpeg, all colors are messed up, not only the background)
Found this bit of code in this rather old thread of the java2d-interest list, thought I'd share, because after a quick test, it is much more performant than your solution:
final WritableRaster raster = img.getRaster();
final WritableRaster newRaster = raster.createWritableChild(0, 0, img.getWidth(), img.getHeight(), 0, 0, new int[]{0, 1, 2});
// create a ColorModel that represents the one of the ARGB except the alpha channel
final DirectColorModel cm = (DirectColorModel) img.getColorModel();
final DirectColorModel newCM = new DirectColorModel(cm.getPixelSize(), cm.getRedMask(), cm.getGreenMask(), cm.getBlueMask());
// now create the new buffer that we'll use to write the image
return new BufferedImage(newCM, newRaster, false, null);
Unfortunately, I can't say I understand exactly what it does ;)

If you create a BufferedImage of type BufferedImage.TYPE_INT_ARGB and save to JPEG weird things will result. In my case the colors are scewed into orange. In other cases the produced image might be invalid and other readers will refuse loading it.
But if you create an image of type BufferedImage.TYPE_INT_RGB then saving it to JPEG works fine.
I think this is therefore a bug in Java JPEG image writer - it should write only what it can without transparency (like what .NET GDI+ does). Or in the worst case thrown an exception with a meaningful message e.g. "cannot write an image that has transparency".

JPEG has no support for transparency. So even when you get the circle color correctly you will still have a black or white background, depending on your encoder and/or renderer.

BufferedImage originalImage = ImageIO.read(getContent());
BufferedImage newImage = new BufferedImage(originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
for (int x = 0; x < originalImage.getWidth(); x++) {
for (int y = 0; y < originalImage.getHeight(); y++) {
newImage.setRGB(x, y, originalImage.getRGB(x, y));
}
}
ImageIO.write(newImage, "jpg", f);
7/9/2020 Edit: added imageIO.write