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Printing a bitmap is a complicated matter. It involves matching the DPI of the image to that of the printer. The Axtel DEMO program uses the following formula:
If the image DPI is the same as the printer DPI, the demo uses a 'BitBlt' to transfer the image to the print page. This means that the image data is copied directly to the printed page without any scaling. Should the image be larger than the page, the right and/or bottom edges are simply clipped.
If the printer DPI does not match the image DPI, 'StretchBlt' is used to scale the image to fit the print page. This makes the image appear to be the correct size but is dangerous for barcodes because some columns can be doubled while others not. For example, consider the case where the image is 200 DPI and the printer is 300 DPI. The image will be scaled up from 200 DPI to 300 DPI in order to match the printer DPI. This has the effect of duplicating every other pixel and introducing a distortion into the barcode. There are two possible solutions to this problem.
Solution One: Start with a 300 DPI TIFF image before writing the barcode. This way, printing to a 300 DPI printer will not distort the barcode.
Solution Two: Set the printer to 600 DPI. This will cause a more regular scaling of 200 DPI to 600 DPI. This will triple each pixel but will not introduce any distortion into the barcode.
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