Develop Reference

Android: image saved using copyPixelsFromBuffer is distorted

I am trying to make an image processing program in Android Studio and I have a problem concerning how to save a Bitmap.
My problem is about saving an image which comes from a ByteBuffer.
To show it here, I have done this: I load an image in a ByteBuffer and I try to save it, rescaled to 1014x1163 pixels. And the image I get is distorted, messy.
For example, here is an image I load:
And here is what I get in the image I save:
Here is my code:
imageSize = (int) (bmWidth*bmHeight*4);
ByteBuffer pixelsArray = ByteBuffer.allocateDirect(imageSize);
ByteBuffer outputArray = ByteBuffer.allocateDirect(imageSize);
workingBitmap.copyPixelsToBuffer(pixelsArray);
workingBitmap.copyPixelsToBuffer(outputArray);
int thiswidth = workingBitmap.getWidth();
int thisheight = workingBitmap.getHeight();
Bitmap copiedBitmap = Bitmap.createScaledBitmap(workingBitmap, Width, Height, false);
int thiswidth2 = copiedBitmap.getWidth();
int thisheight2 = copiedBitmap.getHeight();
outputArray.rewind();
copiedBitmap.copyPixelsFromBuffer(outputArray);
SaveJPG(copiedBitmap);
The function SaveJPG works fine because if I call SaveJPG(workingBitmap) it saves a normal image.
Here is the code with variables values during debugging:
I am wondering if the problem comes from the fact that the output resolution is not a multiple of 4. That's mandatory in my program: the output image resolution can be of any value (odd or even).
I have tried many different things (copying workingBitmap and resizing the copy for example).
No success. I don't know what the cause of the problem is.
Does anyone have some source code which can save an image of any resolution, stored in a ByteBuffer ?
Thanks in advance.

Try this
try (FileOutputStream out = new FileOutputStream(yourFileName)) {
yourBitmap.compress(Bitmap.CompressFormat.PNG, 100, out); // bmp is your Bitmap instance
// PNG is a lossless format, the compression factor (100) is ignored
} catch (IOException e) {
e.printStackTrace();
}
Or use this
MediaStore.Images.Media.insertImage(getContentResolver(), yourbitmap,
"File name", "description of the image");

I have found the cause of the problem. It was simply due to a problem in the width and height of the input image: I was using the width and height of the View which displays the input bitmap, instead of using the bitmap's width and height.

How to save indexed color PNG in java

How to save image in java as java.awt.image.IndexColorModel PNG? I'm loading indexed color png with ImageIO, manipulate it with Catalino library which unfortunately converts the color space to java.awt.image.DirectColorModel.
Now I want to save the result in the exactly same format as the original image. I tried the following snippet of code.
private static void testIndexedColor() throws IOException {
FastBitmap input = new FastBitmap("test.png");
BufferedImage bi = new BufferedImage(input.getWidth(), input.getHeight(), BufferedImage.TYPE_BYTE_INDEXED);
bi.getGraphics().drawImage(input.toBufferedImage(), 0, 0, null);
ImageIO.write(bi, "PNG", new File("test_result.png"));
}
But in the result weird light gray pixel artifacts appeared in the white background, and PPI decreased . How to correctly convert back to indexed color mode without quality loss and distortion?

Assuming I'm correct about the Catalano framework, you should be able to re-write your methods as this:
private static void testIndexedColor() throws IOException {
BufferedImage bi = ImageIO.read(new File("test.png"));
FastBitmap input = new FastBitmap(bi);
Graphics2D g = bi.createGraphics();
try {
g.drawImage(input.toBufferedImage(), 0, 0, null);
}
finally {
g.dispose(); // Good practice ;-)
}
ImageIO.write(bi, "PNG", new File("test_result.png"));
}
At least you should get away with the fixed palette and the artifacts.
However, this will likely still modify the PPI (but this won't affect the pixels). And even in some cases the image might be written back as a non-palette PNG.
Update: It seems the PNGImageWriter (through the PNGMetadata) actually re-writes an IndexColorModel containing a perfect grayscale, to a grayscale PNG by default. This is normally a good idea, as you reduce file size by not writing the PLTE chunk. You should be able to get around this, by passing the metadata from the original, along with the image pixel data, to instruct the writer to keep the IndexColorModel (ie. write PLTE chunk):
private static void testIndexedColor() throws IOException {
File in = new File("test.png");
File out new File("test_result.png");
try (ImageInputStream input = ImageIO.createImageInputStream(in);
ImageOutputStream output = ImageIO.createImageOutputStream(out)) {
ImageReader reader = ImageIO.getImageReaders(input).next(); // Will fail if no reader
reader.setInput(input);
ImageWriter writer = ImageIO.getImageWriter(reader); // Will obtain a writer that understands the metadata from the reader
writer.setOutput(output); // Will fail if no writer
// Now, the important part, we'll read the pixel AND metadata all in one go
IIOImage image = reader.readAll(0, null); // PNGs only have a single image, so index 0 is safe
// You can now access and modify the image data using:
BufferedImage bi = (BufferedImage) image.getRenderedImage();
FastBitmap fb = new FastBitmap(bi);
// ...do stuff...
Graphics2D g = bi.createGraphics();
try {
g.drawImage(fb.toBufferedImage(), 0, 0, null);
}
finally {
g.dispose();
}
// Write pixel and metadata back
writer.write(null, image, writer.getDefaultWriteParam());
}
}
This should (as a bonus) also keep your PPI as-is.
PS: For production code, you also want to dispose() of the reader and writer above, but I left it out to keep focus and avoid further discussion on try/finally. ;-)

How to save a BufferedImage as a File

I am using the imgscalr Java library to resize an image .
The result of a resize() method call is a BufferedImage object. I now want to save this as a file (usually .jpg).
How can I do that? I want to go from BufferedImage -> File but perhaps this is not the correct approach?

File outputfile = new File("image.jpg");
ImageIO.write(bufferedImage, "jpg", outputfile);

The answer lies within the Java Documentation's Tutorial for Writing/Saving an Image.
The Image I/O class provides the following method for saving an image:
static boolean ImageIO.write(RenderedImage im, String formatName, File output) throws IOException
The tutorial explains that
The BufferedImage class implements the RenderedImage interface.
so it's able to be used in the method.
For example,
try {
BufferedImage bi = getMyImage(); // retrieve image
File outputfile = new File("saved.png");
ImageIO.write(bi, "png", outputfile);
} catch (IOException e) {
// handle exception
}
It's important to surround the write call with a try block because, as per the API, the method throws an IOException "if an error occurs during writing"
Also explained are the method's objective, parameters, returns, and throws, in more detail:
Writes an image using an arbitrary ImageWriter that supports the given format to a File. If there is already a File present, its contents are discarded.
Parameters:
im - a RenderedImage to be written.
formatName - a String containg the informal name of the format.
output - a File to be written to.
Returns:
false if no appropriate writer is found.
Throws:
IllegalArgumentException - if any parameter is null.
IOException - if an error occurs during writing.
However, formatName may still seem rather vague and ambiguous; the tutorial clears it up a bit:
The ImageIO.write method calls the code that implements PNG writing a “PNG writer plug-in”. The term plug-in is used since Image I/O is extensible and can support a wide range of formats.
But the following standard image format plugins : JPEG, PNG, GIF, BMP and WBMP are always be present.
For most applications it is sufficient to use one of these standard plugins. They have the advantage of being readily available.
There are, however, additional formats you can use:
The Image I/O class provides a way to plug in support for additional formats which can be used, and many such plug-ins exist. If you are interested in what file formats are available to load or save in your system, you may use the getReaderFormatNames and getWriterFormatNames methods of the ImageIO class. These methods return an array of strings listing all of the formats supported in this JRE.
String writerNames[] = ImageIO.getWriterFormatNames();
The returned array of names will include any additional plug-ins that are installed and any of these names may be used as a format name to select an image writer.
For a full and practical example, one can refer to Oracle's SaveImage.java example.

You can save a BufferedImage object using write method of the javax.imageio.ImageIO class. The signature of the method is like this:
public static boolean write(RenderedImage im, String formatName, File output) throws IOException
Here im is the RenderedImage to be written, formatName is the String containing the informal name of the format (e.g. png) and output is the file object to be written to. An example usage of the method for PNG file format is shown below:
ImageIO.write(image, "png", file);

Create and save a java.awt.image.bufferedImage to file:
import java.io.*;
import java.awt.image.*;
import javax.imageio.*;
public class Main{
public static void main(String args[]){
try{
BufferedImage img = new BufferedImage(
500, 500, BufferedImage.TYPE_INT_RGB );
File f = new File("MyFile.png");
int r = 5;
int g = 25;
int b = 255;
int col = (r << 16) | (g << 8) | b;
for(int x = 0; x < 500; x++){
for(int y = 20; y < 300; y++){
img.setRGB(x, y, col);
}
}
ImageIO.write(img, "PNG", f);
}
catch(Exception e){
e.printStackTrace();
}
}
}
Notes:
Creates a file called MyFile.png.
Image is 500 by 500 pixels.
Overwrites the existing file.
The color of the image is black with a blue stripe across the top.

Download and add imgscalr-lib-x.x.jar and imgscalr-lib-x.x-javadoc.jar to your Projects Libraries.
In your code:
import static org.imgscalr.Scalr.*;
public static BufferedImage resizeBufferedImage(BufferedImage image, Scalr.Method scalrMethod, Scalr.Mode scalrMode, int width, int height) {
BufferedImage bi = image;
bi = resize( image, scalrMethod, scalrMode, width, height);
return bi;
}
// Save image:
ImageIO.write(Scalr.resize(etotBImage, 150), "jpg", new File(myDir));

As a one liner:
ImageIO.write(Scalr.resize(ImageIO.read(...), 150));

Grab image from clipboard on Mac OSX using applet

I am using an Applet to save image from clipboard. The image is saved but something happened with its format. It is darken and lost colors.
here's how I am doing it:
AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
try {
//create clipboard object
Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
//Get data from clipboard and assign it to an image.
//clipboard.getData() returns an object, so we need to cast it to a BufferdImage.
BufferedImage image = (BufferedImage) clipboard.getData(DataFlavor.imageFlavor);
//file that we'll save to disk.
File file = new File("/tmp/clipboard.jpg");
//class to write image to disk. You specify the image to be saved, its type,
// and then the file in which to write the image data.
ImageIO.write(image, "jpg", file);
//getData throws this.
} catch (UnsupportedFlavorException ufe) {
ufe.printStackTrace();
return "Não tem imagem na área de transferência";
} catch (Exception ioe){
ioe.printStackTrace();
}
return null;
}
}
);
I read that Mac uses a different image format but I did not find how to convert it to a format I could save. I imagined that java should have taken care of that.
So, how can I convert the image from clipboard to jpg?
PS. I tried using png instead of jpg, got a worse result: black image

To solve the issue on Mac, I used the solution proposed on The nightmares of getting images from the Mac OS X clipboard using Java.
I pass the retrieved BufferedImage to method that redraws it to new BufferedImage, returning a valid image. Here follows the code from that page:
public static BufferedImage getBufferedImage(Image img) {
if (img == null) return null;
int w = img.getWidth(null);
int h = img.getHeight(null);
// draw original image to thumbnail image object and
// scale it to the new size on-the-fly
BufferedImage bufimg = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = bufimg.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2.drawImage(img, 0, 0, w, h, null);
g2.dispose();
return bufimg;
}
And how I use it:
Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
//Get data from clipboard and assign it to an image.
//clipboard.getData() returns an object, so we need to cast it to a BufferdImage.
BufferedImage image = (BufferedImage) clipboard.getData(DataFlavor.imageFlavor);
if (isMac()) {
image = getBufferedImage(image);
}

PNG is the preferred image format for Macs. You might want to try saving as that and then converting to a JPG if needed afterwards.

Converting PNG into JPEG

I'm having problems converting a simple PNG into a JPEG format.
I'm using the following code:
...
File png = new File(filePath);
try {
SeekableStream s = new FileSeekableStream(png);
PNGDecodeParam pngParams = new PNGDecodeParam();
ImageDecoder dec = ImageCodec.createImageDecoder("png", s, pngParams);
RenderedImage pngImage = dec.decodeAsRenderedImage();
JPEGEncodeParam jparam = new JPEGEncodeParam();
jparam.setQuality(0.50f); // e.g. 0.25f
File jpeg = new File("jpeg.jpeg");
FileOutputStream out = new FileOutputStream(jpeg);
ImageEncoder encoder = ImageCodec.createImageEncoder("JPEG", out, jparam);
encoder.encode(pngImage);
s.close();
} catch (IOException e) {
ok = false;
e.printStackTrace();
}
return ok;
}
...
I end up with an JAI exception ->
java.lang.RuntimeException: Only 1, or 3-band byte data may be written.
at com.sun.media.jai.codecimpl.JPEGImageEncoder.encode(JPEGImageEncoder.java:148) ...
Ran out of options. Any suggestion?

It might be easier to use ImageIO to read the PNG into a BufferedImage and write the image out in JPEG format.
Addendum: In this approach, the conversion is handled transparently by the writer's ImageTranscoder.
BufferedImage img = ImageIO.read(new File("image.png"));
ImageIO.write(img, "jpg", new File("image.jpg"));

you probably have alpha channel in the png that you need to get rid of before trying to write the jpg.
Create a new BufferedImage with type TYPE_INT_RGB (not TYPE_INT_ARGB), and then write your source image (pngImage) onto the new blank image.
Something like this (warning, not tested code):
BufferedImage newImage = new BufferedImage( pngImage.getWidth(), pngImage.getHeight(), BufferedImage.TYPE_INT_RGB);
newImage.createGraphics().drawImage( pngImage, 0, 0, Color.BLACK, null);

I also found that reading a PNG image into a BufferedImage with ImageIO (Java 6) and writing it out to a JPG "format name" corrupted the image. The image was there, but the colors looked "solarized" and almost inverted. The JPG file was much smaller than the PNG file for sure, so a lot of compression was done. I don't see how you might control the compression or color depth.

I had corrupted file after conversion with other solutions but this method worked for me:
public static void formatConverter(String pngFile, String jpgFile) {
try {
File input = new File(pngFile);
File output = new File(jpgFile);
BufferedImage image = ImageIO.read(input);
BufferedImage result = new BufferedImage(
image.getWidth(),
image.getHeight(),
BufferedImage.TYPE_INT_RGB);
result.createGraphics().drawImage(image, 0, 0, Color.WHITE, null);
ImageIO.write(result, "jpg", output);
} catch (IOException e) {
e.printStackTrace();
}
}

I suppse that JAI reads the PNG image with an indexed colour model and is only able to write 8-bit grayscale or 24-bit colour images as JPEG files.
If you are not required to use JAI for this task, you should be able to use ImageIO instead:
ImageIO.write(ImageIO.read(new File("in.png")), "JPEG", new File("out.jpg"));

I was getting the following message in a slightly different context. Getting rid of the alpha channel solved the problem
javax.imageio.IIOException: Sample size must be <= 8
at com.sun.imageio.plugins.jpeg.JPEGImageWriter.write(JPEGImageWriter.java:435)
at javax.imageio.ImageWriter.write(ImageWriter.java:580)
at com.twelvemonkeys.imageio.plugins.jpeg.JPEGImageWriter.write(Unknown Source)
at net.sf.basedb.util.ImageTools.tiffToJpg(ImageTools.java:98)
at net.sf.basedb.util.ImageTools.main(ImageTools.java:118)

see Converting transparent gif / png to jpeg using java
Have a look at the solution that redraws with the graphics environment posted by harmanjd. The solution with the DirectColorModel doesn't compile and should be wiped away. I don't have enough rep points to comment directly there.