imagick convert png to jpg in java with im4java

Question

I need to convert from PNG to JPG.

However, iMagick adds a black background to it.

I saw this question which is for PHP, and tried to write the same for java like this:

// create the a jpg image
ConvertCmd cmd = new ConvertCmd();
// create the operation, add images and operators/options
IMOperation op = new IMOperation();
op.addImage(brandingURL);
op.format("JPEG");
op.composite();
op.background("white");
op.addImage(imageLocation);
//op.transparent();
// execute the operation
cmd.run(op);

But still, the image comes out with a black background.

What am I missing?

Answer 1

I had to write the code like this:

 Info imageInfo = new Info(brandingURL, true);
 IMOperation op = new IMOperation();
 op.addImage(brandingURL);
 op.size(imageInfo.getImageWidth(), imageInfo.getImageHeight());
 op.addImage("xc:white", "c://write//test.jpeg");
 op.addImage("c://write//test.jpeg");
 CompositeCmd composite = new CompositeCmd();
 composite.run(op);

Answer 2

The call to background should not be necessary. Accroding to the documentation, the default background is white, which suugests to me that maybe one of your pictures has a black background that overwrites/blocks the default (maybe the the one at brandingURL?).

Quote from the above linked documentation for ImageMagick:

-background color

Set the background color.

The color is specified using the format described under the -fill option. The default background color (if none is specified or found in the image) is white.

If you are using it precisely because one of the images does specify a (black) background, I suggest you move the background call to either before adding that picture or to the end of the operation (Not sure how ImageMagick operates wrt to this)