Generated barcodes have jagged edges

We have a new application which reads a QR code and, from three values contained therein, generates three barcodes (Code 128) which are stacked vertically and saved as a bitmap. When the bitmap is printed, the lines of the barcodes have jagged edges making them unreadable.

Each barcode is save in a temporary file as a PNG file before being consolidated into the single BMP file. This seems an extraordinary inefficiency. Is there a way to generate each code and write them once into the end result file - could be BMP or PNG. Moreover, is there a way to stream the three stacked barcodes directly to the printer bypassing the need for any interim file.

Lots of questions. Any help would be appreciated. Thanks!

@MailAdminDot

It is requested to kindly share sample QR code along with your code for generating barcode so that we could investigate and suggest properly.