This issue applies to Barcode Java Servlets: If the height and size of the barcode image is specified in the IMG tag without specifying the image size in the barcode parameters, the barcode may be too small, too large, or unable to print correctly. To solve the problem, specify the size of the barcode image and the canvas together.

Example:
Instead of:

<img src="http://server/servlet?BARCODE=123456" width="100" height="100">

Use:

<img src="http://server/servlet?BARCODE=123456&HEIGHT=100&WIDTH=200" width="200" height="100">