public int getNumberOfImages() {
        return numberOfImages;
    }
Returns the number of images in the file.

<p>
Applies mostly to GIF and TIFF; reading PSD/Photoshop layers is not supported, and Jpeg/JFIF EXIF thumbnails are not included in this count.
</p>

@return number of images in the file.
src/main/java/org/apache/commons/imaging/ImageInfo.java