PDF417 characters slightly misaligned

Issues related to using our fonts in Crystal Reports

PDF417 characters slightly misaligned

Postby jbonds(Legacy member) on Tue Jul 26, 2005 8:38 pm

When I print a PDF417 barcode using the GUI encoder, it looks absolutely perfect. Then when I try to print one out using Crystal Reports, the barcode characters come out misaligned slightly. See the image below...

It's kind of hard to see it because of the scan however the right hand side has some roughly 1 pixel "shifts" in the barcode. There are also thin horizontal lines running through the middle where those white dots are on the right and left side of that thick vertical bar. Can anyone help with this?

jbonds(Legacy member)

Re: PDF417 characters slightly misaligned

Postby benz(Legacy Member) on Wed Jul 27, 2005 8:20 am

I believe you made this image by magnifying the print result. It is normal to see that 1 printer pixel is shifted.

The font itself contains the drawing commands. Most of display/printing devices are pixels based. A pixel can either be light or dark. The process of turning the the drawing commands into an array of pixels is called Rasterization. The rasterization usually involves float-point calculation and can not be accurate.

If you print a circle and magnify the print by 10 times, you will see that the smooth circle becomes "jagged".

The rasterizer used by Crystal Reports is not a good one, especially under low resolution. You can find more defects in the print preview.

The problem does not impact the reading. Under printer resolution 200 dpi, a pixel is approximately 5 mils wide. Most scanners are not able to detect such a length. Even they do, the width of a PDF417 module is several times larger than the width of 1 pixel. Unless you are looking to print very small symbols, or use a very low-resolution printer, these factors can be ignored.
benz(Legacy Member)

Re: PDF417 characters slightly misaligned

Postby jbonds(Legacy member) on Wed Jul 27, 2005 5:27 pm

The above image is a scan of a printed barcode. It just seemed strange to me that it would print perfectly with the GUI Encoder and not with Crystal Reports.
jbonds(Legacy member)

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