src/main/java/org/gm4java/im4java/GMOperation.java
public GMOperation addImage(final File file) {
        if (file == null) {
            throw new IllegalArgumentException("file must be defined");
        }
        getCmdArgs().add(file.getPath());
        return this;
    }
public GMOperation addImage(final File file) {
        if (file == null) {
            throw new IllegalArgumentException("file must be defined");
        }
        getCmdArgs().add(file.getPath());
        return this;
    }
Add image to operation.

@param file
image file to be added.
@return Builder object for chained options setup.