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concat image file not able to create

I try to join two images. But not able to create it.
I am not able to understand what is the problem in the below code.
It is not able to create the concat.jpg file.
BufferedImage image = ImageIO.read(mainFile);
BufferedImage image1 = ImageIO.read(fileToMerge);
int width = Math.max(image.getWidth() , image1.getWidth());
int height = Math.max(image.getHeight() , image1.getHeight());
log.info("width {}", width);
log.info("height {}", height);
BufferedImage concatImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics2D = concatImage.createGraphics();
graphics2D.drawImage(image, 0, image.getHeight(), null);
graphics2D.drawImage(image1, 0 , image1.getHeight(), null);
ImageIO.write(concatImage, "jpg", new File(Constants.LOCAL_FOLDER + "/concat.jpg"));

You want the height of concatImage to be the combined height of image and image1.
You want to draw image at coordinates (0,0) and you want to draw image1 at x = 0 and y = height of image
Try the following.
BufferedImage image = ImageIO.read(mainFile);
BufferedImage image1 = ImageIO.read(fileToMerge);
int width = Math.max(image.getWidth() , image1.getWidth());
int height = image.getHeight() + image1.getHeight();
log.info("width {}", width);
log.info("height {}", height);
BufferedImage concatImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics2D = concatImage.createGraphics();
graphics2D.drawImage(image, 0, 0, null);
graphics2D.drawImage(image1, 0, image.getHeight(), null);
ImageIO.write(concatImage, "jpg", new File(Constants.LOCAL_FOLDER + "/concat.jpg"));
Note that you should call graphics2D.dispose() when you no longer need to use it.

Java swing high quality PNG

I have been trying to export my swing 2d diagram to a png file. I tried the following code :
BufferedImage bufferedImage = new BufferedImage(width,height,BufferedImage.TYPE_INT_ARGB);
Graphics2D referenceGraphics = bufferedImage.createGraphics();
referenceGraphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
paintComponent(referenceGraphics);
File imageFile = new File(fileName);
if (imageFile.exists() || imageFile.createNewFile()) {
ImageIO.write(bufferedImage, "png", imageFile);
}
However the png file is been created successfully, but the quality is too low. I need to create at least 300ppi image file. How to achieve that?

Simply increasing the size of the component won't make the resolution of the image any better. It will just be larger. What you need to do is create the BufferedImage larger that the component (i.e. 3 times for 3 times the current resolution) and the scale the Graphics object of the BufferedImage. The resulting code would look something like this:
public static void main(String[] args) throws IOException {
Component comp = ...
BufferedImage img = scaledImageFromComponent(comp, 3);
File imageFile = new File(fileName);
if (imageFile.exists() || imageFile.createNewFile()) {
ImageIO.write(img, "png", imageFile);
}
}
public static BufferedImage scaledImageFromComponent(final Component c, final double scale) {
c.setSize(c.getPreferredSize());
c.doLayout();
Rectangle r = new Rectangle(0, 0, c.getWidth(), c.getHeight());
return scaledImageFromComponent(c, r, scale, scale, false);
}
public static BufferedImage scaledImageFromComponent(final Component c, final Rectangle bounds,
final double scalex, final double scaley,
final boolean print) {
BufferedImage image = createCompatibleTransparentImage((int) (scalex * bounds.width),
(int) (scaley * bounds.height));
final Graphics2D g2d = (Graphics2D) image.getGraphics();
g2d.scale(scalex, scaley);
g2d.translate(-bounds.x, -bounds.y);
if (print) {
c.print(g2d);
} else {
c.paint(g2d);
}
g2d.dispose();
return image;
}
public static BufferedImage createCompatibleTransparentImage(final int width,
final int height) {
return isHeadless() ? new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB)
: getGraphicsConfiguration().createCompatibleImage(width, height,
Transparency.BITMASK);
}
private static boolean isHeadless() {
return GraphicsEnvironment.isHeadless();
}
private static GraphicsConfiguration getGraphicsConfiguration() {
return GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
}
If your diagram contains text you may want to switch Transparency.BITMASK with Transparency.OPAQUE for better anti-aliasing support (on Windows).

Drawing new image over old image java

I need to draw a new image over old image. I first opened both images in BufferedImage and changed their white background to transparent. Then I got a Graphics2D object from the bufferedImage of old image and called drawImage method of Graphics2D class. I then saved the old image to disk. When I open the saved image I find only the old image with white background changed to transparent. Can anyone suggest me what is error with my code or how can I get to fix my error ?
BufferedImage newImage = ImageIO.read(new File("new.png"));
BufferedImage oldImage = ImageIO.read(new File("old.png"));
newImage = makeWhiteTransparent(newImage);
oldImage = makeWhiteTransparent(oldImage);
Graphics2D graphics = (Graphics2D) oldImage.getGraphics();
graphics.drawImage(newImage,null, 0,0);
File outputImage = new File("merged.png");
ImageIO.write(oldImage, "png", outputImage);
My makeWhiteTransparent method goes like this:
public static BufferedImage makeWhiteTransparent(BufferedImage img){
BufferedImage dst = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
dst.getGraphics().drawImage(img, 0, 0, null);
int markerRGB = Color.WHITE.getRGB() | 0xFF000000;
int width = dst.getWidth();
int height = dst.getHeight();
for(int x = 0; x < width; x++){
for(int y = 0; y < height; y++){
int rgb = dst.getRGB(x, y);
if ( ( rgb | 0xFF000000 ) == markerRGB ) {
int value = 0x00FFFFFF & rgb;
dst.setRGB(x, y, value);
}
}
}
return dst;
}
I tried changing graphics.drawImage(newImage, null,0,0) to graphics.drawImage(newImage, 0,0, null) and also changing TYPE_4BYTE_ABGR to TYPE_INT_ARGB as suggested but it did nothing. The error still exists.

This needs to be changed:
graphics.drawImage(newImage,null, 0,0);
to
graphics.drawImage(newImage, 0,0, null);
you are using the wrong version of drawImage - check http://docs.oracle.com/javase/7/docs/api/java/awt/Graphics2D.html
--
Change also the type TYPE_4BYTE_ABGR to TYPE_INT_ARGB
--
Here's how it works for me:
public BufferedImage makeWhiteTransparent(BufferedImage img){
BufferedImage dst = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_INT_ARGB);
dst.getGraphics().drawImage(img, 0, 0, null);
int markerRGB = 0x00ffffff; // Color.WHITE.getRGB() | 0xFF000000;
int width = dst.getWidth();
int height = dst.getHeight();
for(int x = 0; x < width; x++){
for(int y = 0; y < height; y++){
int rgb = dst.getRGB(x, y)&0x00ffffff;
if ( rgb == markerRGB ) {
int value = 0x00FFFFFF & rgb;
dst.setRGB(x, y, value);
}
}
}
return dst;
}
bim = makeWhiteTransparent(bim);
bim2 = makeWhiteTransparent(bim2);
Graphics2D graphics = (Graphics2D) bim.getGraphics();
graphics.drawImage(bim2,0,0, null);
g2.drawImage(bim, w/2-wc/2, h/2-hc/2, null);

I got the answer to my question finally. All I had to do was create a new BufferedImage and draw two images over it. Below is the code that works as expected:
BufferedImage newImage = ImageIO.read(new File("new.png"));
BufferedImage oldImage = ImageIO.read(new File("old.png"));
oldImage = makeWhiteTransparent(oldImage);
newImage = makeWhiteTransparent(newImage);
int width = Math.max(newImage.getWidth(), oldImage.getWidth());
int height = Math.max(newImage.getHeight(), oldImage.getHeight());
BufferedImage combined = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics graphics = combined.getGraphics();
graphics.drawImage(oldImage, 0, 0, null);
graphics.drawImage(newImage, 0, 0, null);
File outputImage = new File("merged.png");
ImageIO.write(combined, "PNG", outputImage);

Black Padding with images in java?

I have this problem. I am using this code to rotate an image but the rotated image has black padding in its corners due to rotation.
How could I remove it?
public static BufferedImage rotate(BufferedImage img, int angle) {
rotate_checked = false;
int w = img.getWidth();
int h = img.getHeight();
BufferedImage dimg =new BufferedImage(w, h, BufferedImage.TYPE_BYTE_GRAY);
Graphics2D g = dimg.createGraphics();
g.rotate(Math.toRadians(angle), w/2, h/2);
g.drawImage(img, null, 0, 0);
return dimg;
}

You need to create a transparent image:
BufferedImage buffer = gc.createCompatibleImage(height, width, Transparency.TRANSLUCENT);
where 'gc' is a Graphics2D object. You can also create one directly with new BufferedImage() of course, but this will give you the most efficient-to-use image for your particular graphics context.

How to resize JLabel ImageIcon?

I'm making a Java Swing application that has the following layout (MigLayout):
[icon][icon][icon][....]
where icon = jlabel and the user can add more icons
When the user adds or removes icons, the others should shrink or grow.
My question is really straightforward: I have a JLabel which contains an ImageIcon; how can I resize this icon?

Try this :
ImageIcon imageIcon = new ImageIcon("./img/imageName.png"); // load the image to a imageIcon
Image image = imageIcon.getImage(); // transform it
Image newimg = image.getScaledInstance(120, 120, java.awt.Image.SCALE_SMOOTH); // scale it the smooth way
imageIcon = new ImageIcon(newimg); // transform it back
(found it here)

Resizing the icon is not straightforward. You need to use Java's graphics 2D to scale the image. The first parameter is a Image class which you can easily get from ImageIcon class. You can use ImageIcon class to load your image file and then simply call getter method to get the image.
private Image getScaledImage(Image srcImg, int w, int h){
BufferedImage resizedImg = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = resizedImg.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2.drawImage(srcImg, 0, 0, w, h, null);
g2.dispose();
return resizedImg;
}

And what about it?:
ImageIcon imageIcon = new ImageIcon(new ImageIcon("icon.png").getImage().getScaledInstance(20, 20, Image.SCALE_DEFAULT));
label.setIcon(imageIcon);
From: Resize a picture to fit a JLabel

This will keep the right aspect ratio.
public ImageIcon scaleImage(ImageIcon icon, int w, int h)
{
int nw = icon.getIconWidth();
int nh = icon.getIconHeight();
if(icon.getIconWidth() > w)
{
nw = w;
nh = (nw * icon.getIconHeight()) / icon.getIconWidth();
}
if(nh > h)
{
nh = h;
nw = (icon.getIconWidth() * nh) / icon.getIconHeight();
}
return new ImageIcon(icon.getImage().getScaledInstance(nw, nh, Image.SCALE_DEFAULT));
}

One (quick & dirty) way to resize images it to use HTML & specify the new size in the image element. This even works for animated images with transparency.

I agree this code works, to size an ImageIcon from a file for display while keeping the aspect ratio I have used the below.
/*
* source File of image, maxHeight pixels of height available, maxWidth pixels of width available
* #return an ImageIcon for adding to a label
*/
public ImageIcon rescaleImage(File source,int maxHeight, int maxWidth)
{
int newHeight = 0, newWidth = 0; // Variables for the new height and width
int priorHeight = 0, priorWidth = 0;
BufferedImage image = null;
ImageIcon sizeImage;
try {
image = ImageIO.read(source); // get the image
} catch (Exception e) {
e.printStackTrace();
System.out.println("Picture upload attempted & failed");
}
sizeImage = new ImageIcon(image);
if(sizeImage != null)
{
priorHeight = sizeImage.getIconHeight();
priorWidth = sizeImage.getIconWidth();
}
// Calculate the correct new height and width
if((float)priorHeight/(float)priorWidth > (float)maxHeight/(float)maxWidth)
{
newHeight = maxHeight;
newWidth = (int)(((float)priorWidth/(float)priorHeight)*(float)newHeight);
}
else
{
newWidth = maxWidth;
newHeight = (int)(((float)priorHeight/(float)priorWidth)*(float)newWidth);
}
// Resize the image
// 1. Create a new Buffered Image and Graphic2D object
BufferedImage resizedImg = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = resizedImg.createGraphics();
// 2. Use the Graphic object to draw a new image to the image in the buffer
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2.drawImage(image, 0, 0, newWidth, newHeight, null);
g2.dispose();
// 3. Convert the buffered image into an ImageIcon for return
return (new ImageIcon(resizedImg));
}

I found that there is a minor edit to this fix from trolologuy on the last line of code, you will need to implement a new ImageIcon to get the code to compile properly (Yes I know this is 10 years ago). I found this to be an easy fix for a one off issue, but Suken Shah and Mr. Polywhirl have a better fix overall.
ImageIcon imageIcon = new ImageIcon("./img/imageName.png"); // assign image to a new ImageIcon
Image image = imageIcon.getImage(); // transform it
Image newimg = image.getScaledInstance(120, 120, java.awt.Image.SCALE_SMOOTH); // scale it smoothly
ImageIcon newImageIcon = new ImageIcon(newimg); // assign to a new ImageIcon instance